Barium Titanate-Based Porous Ceramic Flexible Membrane as a

Subscriber access provided by Iowa State University | Library

Energy, Environmental, and Catalysis Applications

Barium Titanate Based Porous Ceramic flexible Membrane as a Separator for room temperature Sodium Ion Battery Arunkumar R, Ajay Piriya Vijaya Kumar Saroja, and Ramaprabhu Sundara ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b17887 • Publication Date (Web): 03 Jan 2019 Downloaded from http://pubs.acs.org on January 5, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Barium Titanate Based Porous Ceramic Flexible Membrane as a Separator for room temperature Sodium Ion Battery Arunkumar R, Ajay Piriya Vijaya Kumar Saroja, Ramaprabhu Sundara† Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials Technology Centre (NFMTC), Department of Physics,Indian Institute of Technology Madras, Chennai 600036, India †Email:

- [email protected]

Abstract Sodium ion batteries (NIB) are an alternative low-cost battery technology for large-scale energy storage application and the development of high-performance polymer-based electrolytes is crucial for further advancement of low-cost NIB. Though electrode materials provide significant contribution to the energy density of the battery, the separator plays a vital role in deciding the safety, duration and performance of batteries. The glass fiber membrane is considered as the most compatible separator for NIB due to its high ionic conductivity and reasonable performance. But the leakage and flammability of the liquid electrolytes while using glass fiber separator can lead to safety issues. So, herein we present an alternative approach for the first time to replace the glass fiber separator in sodium-ion batteries using porous ceramic membrane (PCM). The Polymer blend based porous ceramic membrane is prepared by a simple solution casting technique and used as the separator in sodium ion battery. The good thermal stability of PCM up to 400C, high ionic conductivity of about 10-3 S cm-1, high electrolyte uptake and porous nature make it a better choice over glass fiber membrane. To demonstrate the applicability of PCM in sodium ion battery, the sodium ion storage property of hard carbon is evaluated using PCM as the separator at room temperature. The specific capacity of hard carbon using PCM based separator is about 270 mAh g-1 at a current density of 30 mA g-1 which is ~23% higher than the glass fiber separator (208 m Ah g-1) at the same current density. The enhancement in specific capacity is due to the compatibility of PCM with sodium electrodes, low interfacial resistance, high sodium ion transference number (0.8) and good electrochemical stability (4.9 V) than the glass fiber separator. This study demonstrates a promising alternative separator to glass fiber membrane, which can lead to the development of a practical and safe sodium ion battery. Keywords: Sodium-Ion Batteries, Charge Transports, Porous Ceramic Membrane, Glass Fiber, Barium Titanate. 1 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 26

Introduction Research on rechargeable batteries has gained an increased attention due to the increasing demand of energy storage devices in various sectors like electric vehicles, portable electronic devices and electric grids. Lithium ion battery (LIB) is currently used in portable electronic devices but the major limitation lies in the low availability of lithium which is about 20 parts per million on earth crusts thereby becoming an expensive technology.1–6Due to these factors, lithium is not affordable for large scale applications like plug-in hybrid electric vehicles, hybrid electric vehicles and grid storage7.So, we need to find an alternative storage technology to lithium, which can balance the cost as well as performance. In this aspect, sodium is an alkali metal next to lithium, which can replace lithium due to similar electrochemical properties. Moreover, sodium is highly abundant in nature (the availability of Na is >1% in earth crusts) and thus can be a better alternative to lithium in terms of cost as well as performance.8–10So, the current research is focused on enhancing the forthcoming parameters of sodium ion batteries; (i) low gravimetric and volumetric energy density due to its high redox potential(ii) poor safety and cycle life of sodium batteries due to the low melting temperature of sodium (370.7 K)3,11. Though the design of suitable electrode materials defines the above parameters, the electrolyte and binder also play a significant contribution to improve the durability of the battery5.Typically, Glass Fiber (GF) is used as a separator for sodium ion batteries because of its high porosity and ionic conductivity. Though GF has these benefits, it has certain limitations like high electrolyte leakage, which leads to drastic fading in capacity after cycling. Also, the use of liquid electrolytes can lead to flammability and explosion thereby increases the risk associated

12,13.

To overcome these

drawbacks, research and development in battery technology is focused on leakage free electrolyte in order to avoid short circuit sas well as to improve cyclic stability. In this regard, various leakage free electrolytes like solid-state electrolytes, gel polymer electrolytes and porous ceramic membranes are investigated in rechargeable lithium ion batteries. Solid-state electrolytes can overcome the safety problem because of the presence of inorganic materials as electrolyte rather than the liquid electrolyte. But, due to the very low ionic conductivity of inorganic materials and high sensitivity to moisture, they are limited to miniature applications like micro batteries. On the other hand, polymer electrolytes are advantageous over solidstate electrolytes due to their good ionic conductivity. Because As the liquid electrolytes are gelled inside the polymer matrices, electrolyte leakage is prevented and firing hazard is reduced 14,15. Among these membranes, porous ceramic membrane is advantageous due to the 2 ACS Paragon Plus Environment

Page 3 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


integrated features of electrolyte and separator. Embedding inorganic nanoparticles inside the porous ceramic membrane increases the ionic conductivity and provides good thermal and mechanical stability16.The presence of continuous ceramic phase enables the compatibility of PCM with metal electrodes. In addition, the presence of cavities and voids in the membrane help to trap liquid electrolytes and thereby aid in obtaining good ionic conductivity comparable to the liquid electrolytes as well as serve as a replacement for commercial separators. Among the various polymer-based electrolytes, PVDF based co polymers are investigated in lithium ion battery due to its high dielectric constant and are electrochemically stable17. For instance, Lanceros-Méndez research group has reported on PVdF and its copolymers P(VdF-HFP) & P(VdF-TrFE) and blend P(VdF-TrFE)/PEO based separators for rechargeable battery applications. It is found that dispersion of ceramics into polymer matrix enhances the thermal, mechanical, electrochemical stability and ionic conductivity18–20. Recently, Manuel Stephan research group has studied on PVdF-HFP based porous ceramic membranes like MgAl2O421,ZrO222, LiAl2O423 and montmorillonite (MMT)24 for lithium ion battery. It is concluded from these studies that PCM is superior to celgard membrane. This is due to its high ionic conductivity, porosity, electrolyte uptake, specific capacity, low leakage, and thermally non-shrinkable and good compatibility with lithium metal electrodes than the celgard membrane-based separators. In the case of NIB, few reports are available on the use of polymer electrolytes due to the low ionic conductivity at room temperature. Jin et. al.have reported Glass fiber (GF), GF/Poly (vinylidene fluoride-co-hexafluoro propylene) GF/PVdFHFP and GF/structurable gel polymer electrolyte (GF/SGPE) for Na-ion batteries. The polymer is coated on the surface of a glass fiber membrane to enhance the performance. Also, it exhibits a high Gurley value (~7.5 fold higher) which results in low ionic conductivity than pristine glass fiber12. But the complete replacement of glass fiber membrane with good ionic conductivity is essential for the development of a safer sodium ion battery. Focusing on this aspect, we have attempted to design a porous ceramic membrane (PCM) as a separator with good ionic conductivity at room temperature and low electrolyte leakages as a replacement to glass fiber membrane for sodium ion battery. The use of filler in the polymer electrolyte enhances the thermal as well as mechanical stability. Use of ferroelectric materials like BaTiO3 as filler increases the ionic conductivity when compared to non-ferroelectric based ceramic materials. The presence of a permanent dipole moment in ferroelectric material helps to extend the conductive layer by a strong interaction with the other constituents of the polymer matrix25,26.Herein, we report on barium titanate (BaTiO3) 3 ACS Paragon Plus Environment


incorporated in PVdF-HFP/PBMA blend as a

porous ceramic membrane prepared by

solution casting method and employed as a separator for sodium-ion batteries. We have demonstrated the performance of hard carbon using the prepared PCM as separator at room temperature. The specific capacity of hard carbon using PCM separator shows about 23 % enhancement when compared to GF separator. The better performance with PCM is due to its compatibility with sodium and less interfacial resistance. From this study, it is evident that porous ceramic membrane can be a promising alternative to GF membrane and can be applied for the futuristic safer sodium ion battery. Result and discussion The surface morphology of BaTiO3 based polymer blend porous ceramic membrane at various magnifications is shown in Figure1a&b. The surface morphology seen in porous ceramic membrane implies that barium titanate is homogeneously held together by these polymers. The pore size of the membrane is observed to be less than 10 µm. The presence of uniform pores and voids on the surface of porous ceramic membrane facilitates to trap more quantity of liquid electrolytes and helps in enhancing the ionic migration between the electrodes. The morphological image of GF membrane shows the presence of a fibrous network with the presence of bigger size pores. Due to the presence of non-uniformity of pores in GF the leakage of electrolyte is more (Figure S1). The digital photographic image (Figure 1c) shows that BaTiO3 based porous ceramic membrane is thin and flexible. Thermogravimetric analysis is used to study the thermal stability of the porous ceramic membrane, which is crucial for safety of batteries. TGA plots of PVdF-HFP/PBMA blend: BaTiO3 (30:70) porous ceramic membrane is shown in Figure 1d. Porous ceramic membrane has an initial weight loss at 100 oC, which is due to the removal of moisture absorbed by the sample. Later, a gradual weight loss (~ 10%) occurs from 243 oC to 400 oC and it denotes the decomposition of polymers. Beyond that, there is a rapid weight loss of about 30%, which implies the degradation of the polymer present in the membrane. The char yield of ~70% at a temperature greater than 500 oC is due to the presence of barium titanate in the membrane. To determine the thermal stability of polymer membrane, TGA is carried out and it shows that nearly 40 % of the membrane gets decomposed at a lower temperature of 300 C (Figure S2). This confirms that the presence of BaTiO3 in the PCM helps to increase the thermal stability of the membrane. From this study, it can be concluded that PCM membrane is stable up to 400 C, which is sufficient for the safe operation during thermal runaway of the battery. 4 ACS Paragon Plus Environment

Page 4 of 26

Page 5 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The structural characteristics of the composite material are studied using X-ray diffraction technique. Figure S3 shows XRD patterns of PVdF-HFP, PBMA and BaTiO3 and porous ceramic membrane. The diffractogram of pure PVdF-HFP shows two peaks indexed at 18oand 20o corresponding to (020) and (100) planes respectively. This implies the crystalline nature of PVdF-HFP. The appearance of broad blunt halo peak at ~18o in PBMA indicates its amorphous nature. Diffractograms of pristine BaTiO3shows sharp peaks at 22o, 31o, 38o, 45o, 50o, 55o, 66o, 70o, 74oand 79ocorresponding to (100), (110), (111), (200), (210), (211), (220), (300), (310) and (311) planes respectively which denotes the tetragonal phase BaTiO3. In porous ceramic membrane, the appearance of sharp crystalline peaks corresponds to barium titanate and a minor peak at ~20o corresponds to PVdF-HFP. This indicates the presence of both BaTiO3 and PVdF-HFP.

5 ACS Paragon Plus Environment


Figure 1. a) &b) Scanning electron microscope image of porous ceramic membrane at different magnifications, (c) Digital photograph of porous ceramic membrane and d) TGA profile of porous ceramic membrane The ionic conductivity of the membrane depends on the uptake of the organic electrolyte inside the membrane. Electrolyte uptake of membrane depends on porosity, pore size and pore volume of the membrane. The porosity of porous ceramic membrane is found to be 60% and that of glass fiber membrane is 66%27. Since the porosity of PCM is about 60%, the electrolyte can be retained in the porous structure. Porous ceramic membrane is activated using liquid electrolyte for 30 minutes and the uptake of electrolytes is measured at different intervals of time. The plot of electrolyte uptake vs time for porous ceramic membrane in terms of % and mg/cm2is shown in Figure S4. Electrolyte uptake of porous ceramic membrane increases with increase in time up to 15 min, beyond which it gets saturated. Electrolyte uptake percentage of porous ceramic membrane is found to be 175% and that of glass fiber is 360%

27–29.

The electrolyte uptake capacity for PCM is found to be 12.92

mg/cm2. Electrolyte uptake of glass fiber is approximately two-fold higher than BaTiO3 based porous ceramic membrane. The above result suggests that glass fiber has high porosity and uptake, which is because of its fiber nature that can entrap a larger amount of the electrolyte. The obtained electrolyte uptake of porous ceramic membrane is sufficient for battery applications and is higher than earlier reports22,30. The mechanical stability of the separator is significant for energy storage devices and is studied by tensile measurement. The stress vs strain behaviour of PCM and GF have been analysed and are shown in Figure 2a&b. Typically, ceramic materials like BaTiO3 are hard and brittle in nature. The presence of BaTiO3 in polymer matrix helps to enhance the mechanical stability. The tensile strength of porous ceramic membrane is 0.9 M Pa with an elongation at break of 18 % and for glass fiber the tensile strength is 0.16 M Pa with an elongation at break of 1.8 %. The mechanical strength of porous ceramic membrane is about ~80 % higher than that of glass fiber membrane. The enhancement of mechanical stability in PCM is due to better interaction between polymer and the ceramic filler BaTiO3. This property again proves that PCM can be a better separator compared to GF.


Page 6 of 26

Page 7 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. Stress-strain behaviour of membrane a) Glass fiber and b) Porous ceramic membrane Figure 3c shows the dependence of ionic conductivity on temperature of porous ceramic membrane and glass fiber saturated with organic electrolyte. The ionic conductivity is calculated from the impedance plot. In the Nyquist plot (Figure 3a & b), the semicircle in the high frequency region followed by a straight line in the low frequency region corresponds to bulk resistance and diffusion of ions respectively. In addition, the effect of blocking electrodes (membrane sandwiched between the stainless-steel electrodes) contributes to the inclined straight line. The semicircular region is not prominent because the charge carriers are ions and the total conductivity is the result of ionic conduction31. The intercept of the inclined straight-line on the x-axis (Z’) gives the value of bulk resistance (Rb) and the ionic conductivity of PCM and GF can be calculated using equation (1). Bulk resistance of PCM and GF are found to decrease with increase in temperature and the low bulk resistance at higher temperature is due to the enhancement in free volume. The ionic conductivities of the membranes (PCM and GF) are calculated by using the following relation, Ionic conductivity (σ) =

L Rb A

(1)

where, L, Rb and A are the thickness, bulk resistance and area of the polymer electrolyte membranes. Ionic conductivity of both PCM and GF are found to increase with increase in temperature (303 to 373 K) which is because of expansion of the polymer matrix at higher temperatures leading to increase in free volume which induces the segmental motion of polymer chain and ion carriers.

32

Ionic conductivity varies from 8.106 10-3 S cm-1 to 20.20

10-3 S cm-1 and from 26.86 to 37.90 10-3 S cm-1 for the porous ceramic membrane and glass fiber respectively. Porous ceramic membrane has huge variation in ionic conductivity at 7 ACS Paragon Plus Environment


higher temperature when compared to glass fiber, which is due to the presence of segmental motion of the polymer chain. Shruti et al. have discussed in detail about the presence of conduction mechanism in a porous ceramic membrane. The ionic migration in PCM occurs at two different levels via; (i) liquid electrolyte absorbed inside pores (ii) swollen region of porous ceramic membrane. The electrolyte absorbed inside the pores of the PCM helps in fast migration of ions and the electrolyte trapped within the swollen region helps in slow migration of ions. Ionic conductivity of PVdF-HFP/PBMA blend-BaTiO3 based porous ceramic membrane has superior ionic conductivity than PVdF-HFP-ZrO233and PVdF-HFP-LiAl2O416based porous ceramic membrane, which has been reported earlier. The enhancement in ionic conductivity of PVdF-HFP/PBMA blend-BaTiO3 matrix is due to the amorphous polymer (PBMA) blended with a high dielectric constant and ferroelectric nature of barium titanate. The use of fillers in the polymer electrolyte enhances the thermal, mechanical stability as well as improves the electrolyte uptake. Among the different fillers available, use of ferroelectric materials like BaTiO3 can increase the ionic conductivity when compared to non-ferroelectric based ceramic materials. The presence of permanent dipole moment in ferroelectric material helps to extend the conductive layer by the strong interaction with the other constituents of the polymer matrix. Due to these positive effects, BaTiO3 is chosen as an additive in the membrane. In order to understand the role of BaTiO3, ionic conductivity of polymer membrane without the addition of BaTiO3 is also carried out at different temperatures as shown in Figure S5. The cole-cole impedance plot suggest that bulk resistance of polymer membrane is ~ 75 % higher than the porous ceramic membrane (with BaTiO3). The obtained bulk resistance of polymer membrane is 35 Ω at 303 K and decreases to 15 Ω at 373 K. The ionic conductivity of polymer membrane is found to be 2.043 x 10-3 S cm-1 at 303 K and increases to 4.766 x 10-3 S cm-1 at 373 K. The obtained ionic conductivity of polymer membrane is lower than the porous ceramic membrane. The detailed changes of ionic conductivity of PCM and GF with temperature are tabulated in Table S1.


Page 8 of 26

Page 9 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. Nyquist plot of membrane at different temperature a) GF& b) PCM and c) Temperature dependent ionic conductivity of PCM & GF The electrolyte leakage in membranes (PCM & GF) are calculated using the following relation, Leakage of electrolyte =

Maf ― Mai Mai

(2)

where, Mai is the initial mass of liquid electrolyte absorbed membrane and Maf is the final mass of the membrane (after applying 75 g of weight on the membrane). Electrolyte leakage of both PCM and glass fiber membrane are calculated and the obtained values are shown in Table 1. PCM has low electrolyte leakage which is ~ 3-fold lower than the GF membrane. The low electrolyte leakage observed in PCM is due to the porous nature which helps to hold more electrolyte without leakage. Tortuosity is a property of a porous structure, which describes the pore connectivity of the solid. Also, it describes the ionic transport through the membrane by providing information about the pore blockage. Tortuosity of any porous membrane can be calculated using equation (3) and if the value of tortuosity of the membrane



Page 10 of 26

is nearly one, it describes an ideal porous network with the possible formation of both cylindrical and parallel pores. σ Tortuosity = [ σ x P] ½ o

(3)

where, P is porosity of the membrane, σ and σo are the ionic conductivities of PCM and liquid electrolytes respectively. Tortuosity of PCM and GF are calculated according to the above equation (3) and are found to be 5.78 and 3.33 respectively. The low tortuosity of separators is essential for the better migration of ions through the separator. It is obvious from the obtained values that BaTiO3 based porous ceramic membrane has sufficient porous network structure to facilitate the movement of sodium ions through the membrane. This value of tortuosity for ceramic membrane is lower when compared to zeolite34 and magnesium aluminate21based porous ceramic membranes. So, BaTiO3 introduced polymer network offers good ionic conductivity and thereby helps in enhancing the specific capacity of sodium ion battery. Further the detailed changes in physical parameters like porosity, electrolyte uptake, leakage and tortuosity of PCM and GF are tabulated in Table 1. Table 1. Physical properties of PCM and GF separator Parameters

Porosity

Electrolyte

Leakage of

Tortuosity

(%)

Uptake (%)

electrolyte (%)

PCM

60 ± 1

175 ± 2

0.044

5.78

GF

66 27

360 27

0.148

3.33

The interfacial stability between separator and sodium metal is crucial which determines the performance, safety and duration of the batteries. The formation of a stable solid electrolyte interface layer on sodium metal anode can reduce the capacity fading and unwanted interactions between electrode-electrolyte interfaces thereby resulting in high coulombic efficiency and long-term stability

16,33.Figure

4 (a&b) shows the cole-cole impedance plot of

PCM and GF for a long duration (138 h) at room temperature. The cole-cole impedance plot shows semi-circles in the higher frequency region, which indicates the formation of a solid electrolyte interface (SEI) layer and an inclined line in the lower frequency region which denotes the diffusion of ions. Interfacial resistance is obtained from intercept on x-axis in cole-cole impedance plot at lower frequency region. The cole-cole impedance plot of both the membranes (PCM & GF) clearly implies that interfacial resistance is found to increase with increase in time. In the case of GF, the expansion of semi-circle occurs at middle frequency 10 ACS Paragon Plus Environment

Page 11 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


region increases with increase in time [Figure. 4a]. This indicates further formation of solid electrolyte interface layer on sodium metal35.But in the case of PCM, the expansion of semicircle is limited after a certain time, which indicates the formation of stable SEI layer. Figure 4 (c&d) shows the plot of interfacial resistance vs time of PCM and GF. Interfacial resistances of both the membranes (PCM & GF) are found to increase with increase in time, which denotes the growth and formation of passivation layer on sodium metal surface. The interfacial resistance of PCM increases from ~710 Ω to ~1515 Ω with increase in time up to 98 h and beyond that the interfacial resistance gets stabilized. The proposed porous ceramic membrane has stable interfacial resistance with sodium metal anode after a period of 98 h. In the case of GF based separator, interfacial resistance increases from ~1010 Ω to ~1950 Ω and gets fluctuated (~1710 Ω), and increases beyond 138 h which implies that GF based separator is not stable with sodium metal for long time when compared to PCM. Further, the value of interfacial resistance of glass fiber separator is about 30 % higher when compared to PCM which results in low ionic migration and leads to poor performance. Barium titanate based porous ceramic membrane provides low interfacial resistance due to the formation of stable layer with sodium metal electrodes when compared to GF based separator, which is due to the compatibility of PCM with Na metal. BaTiO3based PCM has better compatibility when compared to magnesium aluminate (MgAl2O4)21and montmorillonite based porous ceramic membrane with lithium metal anode13. The low and stable interfacial resistance of PCM facilitates faster migration of electrolyte ions and electrons at the electrode-electrolyte interface and thereby helps to attain enhancement in electrochemical performance and better coulombic efficiency.



Page 12 of 26

Figure 4. (a & b) Cole-cole impedance plot of GF and PCM respectively and (c&d) Plot of interfacial resistance vs time of GF (Na/GF/Na) and PCM GF (Na/GF/Na) respectively. Sodium ion transference number is used to determine the electrochemical performance and predicts the performance of the cell. Sodium ion transference numbers (tNa+) of the membranes (PCM & GF) has been studied by chronoamperometric techniques and the cell used for this study comprises of a membrane sandwiched between two symmetric sodium metal electrodes. Sodium ion transference number of the membrane is calculated by using the following relation, tNa+ =

ISS (V ― ROIO) IO (V ― RSSISS)

(4)

where, V is the applied voltage, IO & ISS are initial and steady state current and RO & RSS are resistance before and after perturbation. Figure 5a&b shows current vs time of GF & PCM respectively and inset figure shows the cole-cole impedance plot of the respective membrane before and after polarization. The current decreases with increase in time and later gets stabilized. Sodium ion transference number of PCM and GF are calculated and the values are found to be 0.801 and 0.793 respectively. PCM has achieved higher transference number than 12 ACS Paragon Plus Environment

Page 13 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


GF membrane. This is because of the presence of polar nature C-F bond in PVdF-HFP, which helps to block the perchlorate (ClO4-) anion in separator cum electrolytes. This agrees with the plot of interfacial resistance vs time as shown in Figure 4c &d, wherein the interfacial resistance of PCM is low and thus facilitates better migration of sodium ions when compared to GF. Barium titanate based porous ceramic membrane has high transference number compared to celgard and other porous ceramic membranes/gel polymer electrolytes as reported earlier36,37 The detailed sodium ion transference number and their respective values of PCM and GF are tabulated in Table S2.

Figure 5. Chronoamperometric studies a) GF and b) PCM separator. Inset figure: Nyquist plot before and after polarization of the respective separator. 13 ACS Paragon Plus Environment


Figure 6a&b depict the linear sweep voltammetry studies of porous ceramic membrane and glass fiber separator at the scan rate of 1 mV s-1. Herein, stainless steel is used as the working electrode and sodium metal is used as reference and counter electrode respectively with the membrane in between the electrodes. The PCM and GF have good anodic stability upto 4.9 V and 4.8 V respectively.The PCM based separator has higher electrochemical stability than GF separator because of the presence of electron withdrawing C-F group38. The PCM has good electrolyte retention as well as interfacial stability with electrodes compared to the glass fiber separator which results in better compatibility and can be used for high voltage cathode materials. This leads to the concusion that PCM separator can be useful for the high voltage sodium ion battery 36,39,40. The observed characteristics of the PCM membrane has inspired us to utilize this membrane as separator for the replacement to glass fiber membrane in sodium ion battery. So, the performance of the hard carbon is evaluated using GF and PCM membranes. The preparation technique of the hard carbon is given in the experimental section. The formation of hard carbon is confirmed by XRD analysis as shown in Figure S6 a. The peak observed at 23 corresponds to non graphitazable carbon with an interlayer spacing of 0.37 nm. Also, the morphology of the hard carbon is shown in Figure S6 b, which shows the flake like structure. Initially the electrochemical performance is studied using cyclic voltammetry technique. The cyclic voltammetry curve of hard carbon using PCM separator is shown in Figure 6c. The measurements are carried out in the potential range of 0.01 V to 1.4 V at the scan rate of 0.1 mV/s. The cathodic peak at 0.39 V in the first cycle attributes to the decomposition of electrolytes and the subsequent formation of a solid electrolyte interface (SEI) layer. The absence of peak at 0.39 V in the second and third cycles implies the irreversible process of SEI layer formation. The presence of an anodic peak at 0.135 V and cathodic peak at 0.01 V indicates the intercalation and deintercalation of sodium ions into the hard carbon structure.


Page 14 of 26

Page 15 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 6. Linear sweep voltammetry of a) PCM, b) GF separator c) Cyclic voltammetry curves of hard carbon using PCM separator. The charge discharge profile shows a sloping region in the high potential region and a plateau region in the low potential region. Hard carbon is a non-graphitazable carbon, which has turbostatic nanodomains. The storage of sodium ions in the high voltage region is due to the intercalation of sodium ions into the layers of turbostatic nanodomains. In the low voltage region, the physical adsorption of sodium into the pore and the defect sites takes place. In both GF and PCM, the charge discharge profile looks similar which implies that the mechanism of charge storage is not affected by the use of PCM. In the charge discharge profile shown in Figure 7 (a&b), the sloping as well as plateau region is observed at a low current density of 30 mA/ g. At higher current densities, the surface-controlled process dominates than diffusion-controlled process as reported in previous reports. The specific capacity of Na/PCM/hard carbon and Na/GF/hard carbon are found to be 272 mA h g-1and 205 mA h g-1 at 30 mA g-1 respectively (Figure 7 a&b). The PCM-based separator provides an enhancement of 24% in specific capacity when compared to GF separator. The enhanced specific capacity is mainly attributed to the high ionic conductivity. As observed from the 15 ACS Paragon Plus Environment


SEM image shown in Figure 1a., the presence of uniformly distributed pores on the surface of PCM membrane provide sufficient path ways for the movement of sodium ions. Also, the formation of SEI layer with decreased interfacial resistance, charge transfer resistance with improved electrolyte uptake helps in achieving higher specific capacity. The rate capability studies for PCM are carried out at different current densities of 30 mA g-1, 50 mA g-1, 100 mA g-1, 200 mA g-1, 500 mA g-1 which delivers a specific capacity of 272 mAh g-1, 170 mAh g-1, 130 mAh g-1, 75 mAh g-1 and 30 mAh g-1 respectively. Even when the cell is cycled at a higher current density, the enhancement in specific capacity is retained as shown in Figure 7c. This again confirms that the movement of sodium ions is facilitated even at higher current density due to the presence of porous nature in PCM based membrane. Inspired by the better rate capability, the cyclic stability of hard carbon using PCM and GF membrane are evaluated at a current density of 200 mA g-1(Figure 7d). With the use of PCM based electrolyte the cell shows a specific capacity of 80 mAh g-1which is about 33% enhancement in specific capacity. The coulombic efficiency of the cell is maintained close to 100 % for 100 cycles, which shows the efficient transport of sodium ions through the PCM. The fluctuation in cyclic stability is observed for both glass fiber membrane and porous ceramic membrane. Similar to the fluctuations seen in cycling stability curve (Figure 7d), the fluctuations are also observed in previous report41. When the anode is cycled at a higher current density, the fluctuation in the cyclic stability curve is observed. This might be due to the structural change occurring at the anode during the process of intercalation and deintercalation. In order to confirm the phenomenon, the cyclic stability at lower current density of 100 mA/g is carried out and shown in Figure S7. It is observed from this plot that the fluctuations in the cyclic stability are not observed at lower current density.


Page 16 of 26

Page 17 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7.Charge-discharge profile of hard carbon using a) PCM separator b) GF separator at different current densities, c) Rate capability curve of hard carbon using PCM and GF separator and d) Cyclic stability of hard carbon at a current density of 200 mA g-1 Conclusion Barium titanate based polymer blend porous ceramic membrane, prepared by a solution casting technique, when used as a separator for Na-ion battery, delivers better performance over glass fiber membrane separator. The present study shows that the specific capacity of hard carbon with PCM electrolyte shows about 23% enhancement in specific capacity when compared to glass fiber separator. The formation of thin SEI layer on sodium metal with PCM separator allows the easy migration of sodium ions and thus leads to better performance. Also, the enhancement in specific capacity is due to the compatibility of PCM with sodium electrodes (low interfacial resistance), high sodium ion transference number (0.8), good electrochemical stability (4.9 V) and mechanical stability (0.9 M Pa with 17 ACS Paragon Plus Environment


elongation at break of 18 %) than the glass fiber separator. This study provides an alternative to the existing glass fiber separator, which can lead to a promising safe sodium ion battery. Experimental section Preparation of porous ceramic membrane: The PVdF-HFP/PBMA blend porous ceramic membrane with the composition of 30:70 (wt. %) ratio of polymer and ceramics was prepared by solution casting technique. The calculated quantity of polymers [PVdF-HFP (70): PBMA (30)] were added into the mixture of acetone/DMF (7/3) and stirred until a homogeneous solution was obtained (~10 h). Later the ceramic (BaTiO3) was incorporated into the polymer solution and stirred continuously for 6 h. The resultant slurry was casted onto a glass plate to allow evaporation of the solvent. Thickness of the obtained free-standing film was 25-40 μm. This was stored in a glove box for further characterizations. Preparation of hard carbon: Synthesis of hard carbon was reported by Dahn et al.42Briefly, hard carbon was prepared by using sucrose as the carbon source. Sucrose was caramelized in air at 180 oC for 24 h and then heated at 800 oC for 6 h in argon atmosphere. It was allowed to cool down to room temperature. The obtained powder was ground to form a fine powder. The structure and morphology of the hard carbon are confirmed by XRD and SEM analysis respectively and their figures are shown in Figure S6a&b (Supporting Information). Physical characterizations: The surface morphology and thermal stability of the porous ceramic membrane were studied by field emission scanning electron microscope (FESEM; Inspect F50 at Acceleration voltage of 200 V-30 kV) and thermogravimetry analysis (SDTQ600 analyzer) respectively. The electrolyte uptake, porosity, tortuosity and leakage of electrolyte through the porous ceramic membranes were tested in an argon filled glove box with the moisture level maintained below 0.1 ppm. Tensile measurement of the membranes (PCM & GF) was analyzed by using Bench top Testers 50 k N capacity (model: H50K-S UTM, maker: Tinius Olsen, Horsham). Electrochemical characterizations: Ionic conductivity of porous ceramic membrane and glass fiber were studied by impedance analysis (Biologic SP 300) in the frequency range of 10 mHz to 10kHz at different temperatures (303-373 K).The compatibility of porous ceramic membrane and glass fiber with sodium metal was studied and the assembled cell composed of porous ceramic membrane sandwiched between the sodium non-blocking electrodes. Impedance of PCM and GF were measured at room temperature (25 oC) for a long 18 ACS Paragon Plus Environment

Page 18 of 26

Page 19 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


duration(140 h). Sodium transference numbers were studied by chronoamperometric technique (Na/PCM or GF/Na) at step voltage of 10 mV s-1. Na-ion coin cell (2032) was assembled by using the prepared porous ceramic membrane/ glass fiber as separator, hard carbon and sodium metal (sigma Aldrich) were used as working and counter electrodes respectively. The prepared PCM was soaked in1 M NaClO4 in ethylene carbonate: diethyl carbonate (1:1) for 30 minutes and wiped with Whatman filter paper to remove the excess electrolytes and used as separator cum electrolyte. The hard carbon anode was prepared by mixing 75% of active material 15% of PVdF binder and 10 wt% of acetylene black with NMP as the solvent. Finally, the obtained slurry was coated on copper foil and dried at 80 oC in vacuum oven for 12 h. The fabricated cell was subjected to various electrochemical studies and the charge-discharge profiles of hard carbon with PCM and GF separator were analyzed at various current densities (30, 50, 100, 200 & 500 mA g-1) in the potential range of 0 to 1.5 V at room temperature. Cyclic voltammetry of hard carbon with PCM was studied at the scan rate of 0.1 mV s-1 in a potential range of 0 to 1.4 V. The electrochemical stability of porous ceramic membrane and glass fiber were studied by linear sweep voltammetry analysis at the scan rate of 1 mV s-1 and the cell contains the membrane sandwiched between sodium and stainlesssteel electrode (Na/membrane (PCM or GF)/SS). Acknowledgement The authors thank Indian Institute of Technology, Madras and RCI, Hyderabad (through DRDO project) for supporting this work. Supporting Information Supporting information contains SEM image of glass fiber separator, TGA plot of polymer membrane, XRD pattern of pristine PVdF-HFP, PBMA BaTiO3 and porous ceramic membrane, plot of electrolyte uptake vs time for porous ceramic membrane, Cole-Cole impedance plot and temperature dependent ionic conductivity of polymer membrane, XRD pattern and SEM image of hard carbon, table describing the ionic conductivity of PCM, glass fiber and polymer membrane, sodium ion transference number of PCM and GF membrane.



References (1)

Bauer, A.; Song, J.; Vail, S.; Pan, W.; Barker, J.; Lu, Y. The Scale-up and Commercialization of Nonaqueous Na-Ion Battery Technologies. Adv. Energy Mater. 2018, 1702869, 1–13.

(2)

Delmas, C. Sodium and Sodium-Ion Batteries: 50 Years of Research. Adv. Energy Mater. 2018, 1703137, 1–9.

(3)

Yabuuchi, N.; Kubota, K.; Dahbi, M.; Komaba, S. Research Development on SodiumIon Batteries. Chem. Rev. 2014, 114 (23), 11636–11682.

(4)

Wang, L. P.; Yu, L.; Wang, X.; Srinivasan, M.; Xu, Z. J. Recent Developments in Electrode Materials for Sodium-Ion Batteries. J. Mater. Chem. A 2015, 3 (18), 9353– 9378.

(5)

Kim, S. W.; Seo, D. H.; Ma, X.; Ceder, G.; Kang, K. Electrode Materials for Rechargeable Sodium-Ion Batteries: Potential Alternatives to Current Lithium-Ion Batteries. Adv. Energy Mater. 2012, 2 (7), 710–721.

(6)

Slater, M. D.; Kim, D.; Lee, E.; Johnson, C. S. Sodium-Ion Batteries. Adv. Funct. Mater. 2013, 23 (8), 947–958.

(7)

Pan, H.; Hu, Y.-S.; Chen, L. Room-Temperature Stationary Sodium-Ion Batteries for Large-Scale Electric Energy Storage. Energy Environ. Sci. 2013, 6 (8), 2338.

(8)

Ellis, B. L.; Nazar, L. F. Sodium and Sodium-Ion Energy Storage Batteries. Curr. Opin. Solid State Mater. Sci. 2012, 16 (4), 168–177.

(9)

Kundu, D.; Talaie, E.; Duffort, V.; Nazar, L. F. The Emerging Chemistry of Sodium Ion Batteries for Electrochemical Energy Storage. Angew. Chemie - Int. Ed. 2015, 54 (11), 3432–3448.

(10)

Hwang, J. Y.; Myung, S. T.; Sun, Y. K. Sodium-Ion Batteries: Present and Future. Chem. Soc. Rev. 2017, 46 (12), 3529–3614.

(11)

Dahbi, M.; Yabuuchi, N.; Kubota, K.; Tokiwa, K.; Komaba, S. Negative Electrodes for Na-Ion Batteries. Phys. Chem. Chem. Phys. 2014, 16 (29), 15007–15028. 20 ACS Paragon Plus Environment

Page 20 of 26

Page 21 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(12)

Kim, J. Il; Choi, Y.; Chung, K. Y.; Park, J. H. A Structurable Gel-Polymer Electrolyte for Sodium Ion Batteries. Adv. Funct. Mater. 2017, 27 (34), 1–7.

(13)

Luo, X.; Pan, W.; Liu, H.; Gong, J.; Wu, H. Glass Fiber Fabric Mat as the Separator for Lithium-Ion Battery with High Safety Performance. Ionics (Kiel). 2015, 21 (11), 3135–3139.

(14)

Zhu, Y.; Xiao, S.; Shi, Y.; Yang, Y.; Hou, Y.; Wu, Y. A Composite Gel Polymer Electrolyte with High Performance Based on Poly(Vinylidene Fluoride) and Polyborate for Lithium Ion Batteries. Adv. Energy Mater. 2014, 4 (1), 1–9.

(15)

Zhang, J.; Sun, B.; Huang, X.; Chen, S.; Wang, G. Honeycomb-like Porous Gel Polymer Electrolyte Membrane for Lithium Ion Batteries with Enhanced Safety. Sci. Rep. 2014, 4, 1–7.

(16)

Arora, P.; Zhang, Z. Battery Separators. Chem. Rev. 2004, 104 (10), 4419–4462.

(17)

Kim, I.; Kim, B. S.; Nam, S.; Lee, H. J.; Chung, H. K.; Cho, S. M.; Luu, T. H. T.; Hyun, S.; Kang, C. Cross-Linked Poly(Vinylidene Fluoride-Cohexafluoropropene) (PVDF-Co-HFP) Gel Polymer Electrolyte for Flexible Li-Ion Battery Integrated with Organic Light Emitting Diode (OLED). Materials (Basel). 2018, 11 (4), 1–11.

(18)

Costa, C. M.; Nunes-Pereira, J.; Rodrigues, L. C.; Silva, M. M.; Ribelles, J. L. G.; Lanceros-Méndez, S. Novel Poly(Vinylidene FluorideTrifluoroethylene)/Poly(Ethylene Oxide) Blends for Battery Separators in Lithium-Ion Applications. Electrochim. Acta 2013, 88, 473–476.

(19)

Nunes-Pereira, J.; Costa, C. M.; Sousa, R. E.; Machado, A. V.; Silva, M. M.; Lanceros-Méndez, S. Li-Ion Battery Separator Membranes Based on Barium Titanate and Poly(Vinylidene Fluoride-Co-Trifluoroethylene): Filler Size and Concentration Effects. Electrochim. Acta 2014, 117, 276–284.

(20)

Nunes-Pereira, J.; Costa, C. M.; Leones, R.; Silva, M. M.; Lanceros-Méndez, S. Li-Ion Battery Separator Membranes Based on Poly(Vinylidene FluorideTrifluoroethylene)/Carbon Nanotube Composites. Solid State Ionics 2013, 249–250, 63–71.



(21)

Raja, M.; Angulakshmi, N.; Thomas, S.; Kumar, T. P.; Stephan, A. M. Thin, Flexible and Thermally Stable Ceramic Membranes as Separator for Lithium-Ion Batteries. J. Memb. Sci. 2014, 471, 103–109.

(22)

Suriyakumar, S.; Raja, M.; Angulakshmi, N.; Nahm, K. S.; Stephan, A. M. A Flexible Zirconium Oxide Based-Ceramic Membrane as a Separator for Lithium-Ion Batteries. RSC Adv. 2016, 6 (94), 92020–92027.

(23)

Raja, M.; Sanjeev, G.; Prem Kumar, T.; Manuel Stephan, A. Lithium Aluminate-Based Ceramic Membranes as Separators for Lithium-Ion Batteries. Ceram. Int. 2015, 41 (2), 3045–3050.

(24)

Raja, M.; Kumar, T. P.; Sanjeev, G.; Zolin, L.; Gerbaldi, C.; Stephan, A. M. Montmorillonite-Based Ceramic Membranes as Novel Lithium-Ion Battery Separators. Ionics (Kiel). 2014, 20 (7), 943–948.

(25)

Sun, H. Y.; Takeda, Y.; Imanishi, N.; Yamamoto, O.; Sohn, H.-J. Ferroelectric Materials as a Ceramic Filler in Solid Composite Polyethylene Oxide-Based Electrolytes. J. Electrochem. Soc. 2000, 147 (7), 2462.

(26)

Nunes-Pereira, J.; Costa, C. M.; Sousa, R. E.; Machado, A. V.; Silva, M. M.; Lanceros-Méndez, S. Li-Ion Battery Separator Membranes Based on Barium Titanate and Poly(Vinylidene Fluoride-Co-Trifluoroethylene): Filler Size and Concentration Effects. Electrochim. Acta 2014, 117, 276–284.

(27)

Zhu, J.; Yanilmaz, M.; Fu, K.; Chen, C.; Lu, Y.; Ge, Y.; Kim, D.; Zhang, X. Understanding Glass Fiber Membrane Used as a Novel Separator for Lithium-Sulfur Batteries. J. Memb. Sci. 2016, 504, 89–96.

(28)

Alcoutlabi, M.; Lee, H.; Watson, J. V.; Zhang, X. Preparation and Properties of Nanofiber-Coated Composite Membranes as Battery Separators via Electrospinning. J. Mater. Sci. 2013, 48 (6), 2690–2700.

(29)

Lee, H.; Alcoutlabi, M.; Watson, J. V.; Zhang, X. Electrospun Nanofiber-Coated Separator Membranes for Lithium-Ion Rechargeable Batteries. J. Appl. Polym. Sci. 2013, 129 (4), 1939–1951.


Page 22 of 26

Page 23 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(30)

Gören, A.; Costa, C. M.; Tamaño Machiavello, M. N.; Cíntora-Juárez, D.; NunesPereira, J.; Tirado, J. L.; Silva, M. M.; Gomez Ribelles, J. L.; Lanceros-Méndez, S. Effect of the Degree of Porosity on the Performance of Poly(Vinylidene FluorideTrifluoroethylene)/Poly(Ethylene Oxide) Blend Membranes for Lithium-Ion Battery Separators. Solid State Ionics 2015, 280, 1–9.

(31)

Ahad, N.; Saion, E.; Gharibshahi, E. Structural, Thermal, and Electrical Properties of PVA-Sodium Salicylate Solid Composite Polymer Electrolyte. J. Nanomater. 2012, 2012, 94.

(32)

Michael, M. .; Jacob, M. M. .; Prabaharan, S. R. .; Radhakrishna, S. Enhanced Lithium Ion Transport in PEO-Based Solid Polymer Electrolytes Employing a Novel Class of Plasticizers. Solid State Ionics 1997, 98 (3–4), 167–174.

(33)

Ostrovskii, D.; Ronci, F.; Scrosati, B.; Jacobsson, P. Reactivity of Lithium Battery Electrode Materials toward Non-Aqueous Electrolytes: Spontaneous Reactions at the Electrode-Electrolyte Interface Investigated by FTIR. J. Power Sources 2001, 103 (1), 10–17.

(34)

Nunes-Pereira, J.; Lopes, A. C.; Costa, C. M.; Rodrigues, L. C.; Silva, M. M.; Lanceros-Méndez, S. Microporous Membranes of NaY Zeolite/Poly(Vinylidene Fluoride- Trifluoroethylene) for Li-Ion Battery Separators. J. Electroanal. Chem. 2013, 689, 223–232.

(35)

Shubha, N.; Prasanth, R.; Hng, H. H.; Srinivasan, M. Study on Effect of Poly (Ethylene Oxide) Addition and in-Situ Porosity Generation on Poly (Vinylidene Fluoride)-Glass Ceramic Composite Membranes for Lithium Polymer Batteries. J. Power Sources 2014, 267, 48–57.

(36)

Zhu, Y.; Yang, Y.; Fu, L.; Wu, Y. A Porous Gel-Type Composite Membrane Reinforced by Nonwoven: Promising Polymer Electrolyte with High Performance for Sodium Ion Batteries. Electrochim. Acta 2017, 224, 405–411.

(37)

Yang, Y. Q.; Chang, Z.; Li, M. X.; Wang, X. W.; Wu, Y. P. A Sodium Ion Conducting Gel Polymer Electrolyte. Solid State Ionics 2015, 269, 1–7.

(38)

Zhu, Y.; Wang, F.; Liu, L.; Xiao, S.; Yang, Y.; Wu, Y. Cheap Glass Fiber Mats as a 23 ACS Paragon Plus Environment


Matrix of Gel Polymer Electrolytes for Lithium Ion Batteries. Sci. Rep. 2013, 3 (3187), 6–11. (39)

Rao, M. M.; Liu, J. S.; Li, W. S.; Liang, Y.; Zhou, D. Y. Preparation and Performance Analysis of PE-Supported P(AN-Co-MMA) Gel Polymer Electrolyte for Lithium Ion Battery Application. J. Memb. Sci. 2008, 322 (2), 314–319.

(40)

Gao, H.; Guo, B.; Song, J.; Park, K.; Goodenough, J. B. A Composite GelPolymer/Glass-Fiber Electrolyte for Sodium-Ion Batteries. Adv. Energy Mater. 2015, 5 (9), 1–8.

(41)

Xu, W.; Zhao, K.; Zhang, L.; Xie, Z.; Cai, Z.; Wang, Y. SnS2@Graphene Nanosheet Arrays Grown on Carbon Cloth as Freestanding Binder-Free Flexible Anodes for Advanced Sodium Batteries. J. Alloys Compd. 2016, 654, 357–362.

(42)

Stevens, D. A.; Dahn, J. R. High Capacity Anode Materials for Rechargeable SodiumIon Batteries. J. Electrochem. Soc. 2000, 147 (4), 1271.


Page 24 of 26

Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Graphical abstract


ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

ACS Paragon Plus Environment

Page 26 of 26

Barium Titanate-Based Porous Ceramic Flexible Membrane as a

Recommend Documents