A Perspective on Electrode Materials of Sodium-ion Batteries towards

Subscriber access provided by Kaohsiung Medical University

Perspective

A Perspective on Electrode Materials of Sodiumion Batteries towards Practical Application Yangyang Huang, Yuheng Zheng, Xiang Li, Felix Adams, Wei Luo, Yunhui Huang, and Liangbing Hu ACS Energy Lett., Just Accepted Manuscript • DOI: 10.1021/acsenergylett.8b00609 • Publication Date (Web): 06 Jun 2018 Downloaded from http://pubs.acs.org on June 6, 2018

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 Energy Letters

A Perspective on Electrode Materials of Sodium-ion Batteries towards Practical Application Yangyang Huang,1,3 Yuheng Zheng,1 Xiang Li,1 Felix Adams,2 Wei Luo,1* Yunhui Huang1* and Liangbing Hu2* 1

Institute of New Energy for Vehicles, School of Materials Science and Engineering,

Tongji University, Shanghai 201804, China 2

Department of Materials Science and Engineering, University of Maryland, College Park,

MD 20742, USA 3

Dongguan McNair New Power Co., Ltd, Guangdong 523800, China

ACS Paragon Plus Environment

ACS Energy Letters 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

TOC Graphic


Page 2 of 26

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

ACS Energy Letters

Abstract: Advances in developing affordable batteries are vital for integrating renewable and environmentally friendly energy sources into the power grid. Benefiting from the abundance of sodium resource, sodium-ion batteries (SIBs) have attracted great attention as one of the most promising energy storage and conversion devices for grid-scale energy storage systems. From this perspective, we present a succinct and critical survey of the emerging electrode materials, such as layered transition metal oxides, polyanionic compounds, Prussian blue analogue cathode materials, and hard carbon anode materials that have potential value for large scale applications.



As the global demand for energy increases rapidly and it becomes clear that the use of fossil fuels has substantial consequences for our climate, developing green, renewable, and carbon-neutral energy sources is critical. However, renewable energy sources, such as solar and wind, are typically intermittent. Therefore, developing sustainable electrical energy storage (EES) technologies for stationary applications is crucial and has attracted tremendous research attention. Secondary batteries among various EES technologies present the most suitable pattern in terms of energy density and conversion efficiency.1-2 Lithium-ion batteries (LIBs) with high energy density and long cycle life have been successfully developed as power sources for portable electronic devices. The application of LIBs in electric vehicles (EVs) lead to an increase in cost due to the limited and uneven distribution of lithium reserves.3 Low-cost EES that uses naturally abundant raw materials is urgently required, especially for large-scale stationary applications. Similar to LIBs, SIBs are a class of rechargeable batteries where sodium ions are used as charge carriers. Considering the similar physical and chemical properties with LIBs, along with the huge abundance and low-cost of Na, SIBs have recently been considered as an ideal stationary energy storage technology.4 SIBs can be manufactured in the same way as LIBs, which makes it possible for the LIBs manufacturers to produce SIBs using the existing production lines. Furthermore, the overall production costs and risk factor can be reduced using low-cost aluminum as current collectors for both cathodes and anodes. Recent cost analysis on LiNi0.8Co0.1Mn0.1O2/graphite cell and NaNi0.6Co0.05Mn0.35O2/hard carbon cell shows that the cost of the former is about


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

ACS Energy Letters

$0.11/W h whilst for the latter is $0.14/W h.5-6 Although the latter is higher at this stage, the cost of SIB is potentially lower upon the further development of SIBs. In the past decade, significant progress has been made on electrode material, electrolyte, current collector, and cell configuration for SIBs. The cost of electrode material accounts for a large part of SIB cost. As a result, electrode material is still a key topic, especially in regard to mass applications. In this perspective, we are focusing on cathode and anode materials with these characteristics: high performance, low-cost, abundance, low environmental impact, long lasting, and safe. On the cathode side, we introduce layered metal oxides, polyanionic compounds, and prussian blue analogues (PBA). For anodes, we focus on hard carbon materials. Since there are many comprehensive review papers on some other electrode materials,4-5 such as alloy compounds, TiO2, and quaternary oxides, details on them will not be repeated due to the space limitations.

Layered metal oxides. Layered metal oxides with the general formula NaxMO2 (x ≤ 1, M represents one or more metal ions, Ni, Co, Fe, Mn, Cu etc.) are the most studied cathodes due to their high capacity and working voltage. Typical layered metal oxides can be classified into two main groups, P2 and O3-types, depending on the exact position of the alkali metal and the number of alkali metal layers in the structure perpendicular to the layering.7 “P” and “O” represents prismatic and octahedral sites occupied by Na ions. In a lattice made up of hexagonal sheets, there are three possible positions for the oxygen atoms, conventionally named A, B and C. For example, when



the layers are packed in the order ABCABC, an O3 structure is obtained. Among all layered metal oxides, the Co and Ni containing materials exhibit large reversible capacities and high voltages.8-11 However, they cannot satisfy the cost requirements for large-scale batteries. Fe and Mn based layered oxides are appealing owing to their natural abundance and potential low cost. P2-Na2/3[Fe1/2Mn1/2]O2 delivers a large specific capacity of 190 mAh/g with an average voltage of 2.75 V based on the Fe2+/Fe3+ and Mn3+/Mn4+ redox couples, of which the energy density is estimated to be 520 Wh/kg versus Na metal (Figure 1a).12 Unfortunately, the cycling stability of P2-Na2/3[Fe1/2Mn1/2]O2 is relatively poor due to the irreversible phase transitions during electrochemical Na insertion/extraction cycles. In general, P2 phase could transform to OP4 phase upon charging above 3.8 V. Compared with the P2-O2 phase transition, the P2-OP4 phase transformation is more reversible.13-14 Nazar et al. found that the formation of OP4 phase and a new poor crystalline “Z” phase (NaxFe0.5Mn0.5O2 x ≤ 0.25) resulted from migration of Fe3+ into tetrahedral sites15 and this migration is highly reversible. In addition, cation doping is an effective way to improve the structural stability of P2-type cathodes by suppressing the phase transition and Jahn–Teller structural distortion. For example, P2-Na2/3Mn0.8Fe0.1Ti0.1O2 shows improved cycling life and a fast Na+ mobility.16 Another shortcoming of P2 phase materials is the small proportion of Na ions, resulting in a low desodiation capacity in the initial cycle. Armand et al. reported that the Na deficiency issue can be effectively relieved by the introduction of Na3N (Figure 1c).17 However, the formation of N2 gas due to the decomposition of


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

ACS Energy Letters

Na3N would result in potential safety issues. O3-phase Na[Mn1/2Fe1/2]O2 can be synthesized by controlling the ratio of Na/[Mn and Fe]. As shown in Figure 1b, O3-phase Na[Mn1/2Fe1/2]O2 exhibits a larger polarization than that of P2-phase due to O3-phase suffers from more complex irreversible phase transitions.12 Moreover, Nax[Mn1/2Fe1/2]O2 is sensitive to air. In particular, the uptake of CO2 and oxidation by water lead to the formation of inactive Mn4+ and NaOH, respectively.18 To improve the air stability and its cycling performance, Hu et al. designed a new air-stable O3-Na0.9Cu0.22Fe0.3Mn0.48O2, showing unexpectedly superior stability against moisture.19 Even after soaking in water and stored in air for one month, there is no change in the structure and cycling performance (Figure 1d, 1e). Moreover, a prototype SIB has been fabricated with this cathode and hard carbon anode, which demonstrated a high energy density of 210 Wh/kg (Figure 1f) and excellent cycling stability (Figure 1g). Typically, three synthetic methods including sol-gel method, solid-state method, and co-precipitation method are used to prepare layered metal oxides. Sol-gel methods require an additional separate gel-forming step at elevated temperature, which increases the difficulty of industrialization. At this stage, solid-state and co-precipitation methods are the preferred ways to produce layered metal oxides for commercial applications. Ma et al. synthesized O3-NaNi1/3Fe1/3Mn1/3O2 in large scale by using the modified hydroxide co-precipitation technique combined with solid-state method, showing good electrochemical performance under various temperature conditions.20 1.0 Ah pouch cells using the prepared cathode and hard carbon anode



Page 8 of 26

were manufactured, which exhibited excellent cycling performance with capacity retention over 73% after 500 cycles at 1.0 C rate (Figure 1h). Dou et al. used co-precipitation

method

to

prepare

a

novel

air-stable

O3-type

Na[Li0.05Mn0.5Ni0.3Cu0.1Mg0.05]O2, which exhibited remarkable capacity retention of 81.6% after 400 cycles at 1.0 C (Figure 1i).21 Faradion Co. Ltd. fabricated NaaNi1-x-y-zMnxMgyTizO2 via solid-state method, which is already available in the market.22-23 Although this material exhibited excellent electrochemical performance, the usage of Ni leads to a high cost.

Figure 1. The charge/discharge curves for (a) Na2/3Mn1/2Fe1/2O2 and (b) NaMn1/2Fe1/2O2. (a) and (b) Reprinted with permission from ref. 12. Copyright 2012 Nature Publishing Group. (c) Cycle life evolution of Na0.67[Fe0.5Mn0.5]O2 with various Na3N contents. Reprinted with permission from ref. 17. Copyright 2016 Elsevier. (d) XRD patterns and (e) cycling performance of the O3-Na0.9Cu0.22Fe0.3Mn0.48O2 stored


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

ACS Energy Letters

in air for one month. (f) The schematic and charge/discharge curves of pouch cells using O3-Na0.9Cu0.22Fe0.3Mn0.48O2 cathode and hard carbon anode. (g) Cycling performance of the pouch cells in (f). (d−g) Reprinted with permission from ref. 19. Copyright 2016 Wiley. (h) Galvanostatic charge/discharge profiles of 1.0 Ah pouch cells using O3-NaNi1/3Mn1/3Fe1/3O2 cathode and hard carbon anode. Reprinted with permission from ref. 20. Copyright 2016 The Electrochemical Society. (i) Cycling performance of Na[Li0.05Ni0.3Mn0.5Cu0.1Mg0.05]O2 at various current densities. Reprinted with permission from ref. 21. Copyright 2017 Wiley.

Polyanionic compounds. Several research groups highlighted polyanionic compounds as high-voltage cathode materials. The formula of these polyanionic compounds could be expressed as NaxMM’(XO4)3 (M = V, Ti, Fe, Tr, Al, or Nb etc.; X = P or S, x = 0−4). These polyanionic compounds are embedded with Mn+/(n+1)+ redox in a framework of strongly covalent bonded polyanion units (XO4n−), and are thus highly stable in terms of structure rearrangement during Na+ insertion/extraction and thermal abuse tolerance. Figure 2a demonstrates a series of Na3V2(PO4)2F1+2xO2-2x (0 ≤ x ≤ 1). The redox in these compounds usually provides higher voltages, and could be tuned by replacing the XO4 with F− or O− depending on their difference in electronegativity, as show in Figure 2b.24 Among various polyanionic compounds, Na3V2(PO4)3 provides stable cycling and high Na+ diffusion rate within its 3D ion transportation channels. It exhibits a NASICON (Na super ionic conductor, originated from Na1+xZr2P3-xSixO12, which has superior Na-ion conductivity) type structure with relatively high voltage and long-term cycling capability. To improve the energy density, PO4 polyanion could be replaced by other groups, such as PO4F, P2O7, and F.



These novel compounds usually provide V3+/V4+ redox with higher voltage, indicating higher energy densities. The Na3V2(PO4)2F1+2xO2-2x (0 ≤ x ≤ 1) family is another promising one among these voltage-tunable NASICON typed polyanionic compounds.25 As shown in Figure 2a, the O and F substitute each other with a different stoichiometric ratio, and would provide V3+/V4+ redox with higher potential along with F element (more electronegativity) increasing and O decreasing consequently (Figure 2c−d). This is a fantastic trait since it creates the potential for tuning the positive electrode materials, which could fit the specific HOMO-LOMO gap of the electrolyte. All of these compositions exhibit exceptional volume changes upon Na+ uptake and removal (~2%) with energy density of about 500 Wh/kg. Most recently, it was found that Na3V2(PO4)2FO2 could uptake additional Na atoms, to achieve Na4V2(PO4)2FO2 with a plateau potential at about 1.5 V,26 which further extends the energy density to about 600 Wh/kg. Although the above-mentioned V-based polyanionic compounds provide impressive energy density, they exhibit low electron conductivity and elemental toxicity. There are several 3.0 V Fe-based phosphate PO4 insertion compounds that have been reported.27 By replacing phosphate (PO4) with SO4, the potential of Fe2+/Fe3+ redox couple in Na2Fe2(SO4)3 reaches about 3.8 V against Na/Na+.28 Figure 2e presents the structure of this earth-abundant composition, which exhibits a high energy density (540 Wh/kg), high rate capability (Figure 2f), and excellent capacity retention at 20 C.


Page 10 of 26

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

ACS Energy Letters

Figure 2. Polyanionic compounds as cathode for SIBs. (a) The structure of the Na3V2(PO4)2F1+2xO2-2x (0 ≤ x ≤ 1). (b) Potentials of different redox couples in different polyanionic frameworks. Reprinted with permission from ref. 24. Copyright 2014 Wiley. (c, d) The voltage profiles of Na3V2(PO4)2F1+2xO2-2x (0 ≤ x ≤ 1). Reprinted with permission from ref. 25. Copyright 2014 Wiley. (e) The structure and (f) Voltage profiles of Na2Fe2(SO4)3. Reprinted with permission from ref. 28. Copyright 2014 Nature Publishing Group.

Prussian blue analogues (PBA). PBA with the general chemical formula NaxM1M2(CN6) (M1 and M2 = Fe, Mn, Ni, Co) have been investigated as promising cathodes in both aqueous and nonaqueous batteries. Among all PBA, NaxMFe(CN)6 is the best choice due to the nontoxic and low-cost priorities. Generally, the electrochemical performance of PBA is influenced by its phase purity, crystallinity, defects, and water content. The presence of vacancies and coordinating water in the structural framework can cause a distorted lattice, resulting in lower efficiency and poor cycling life. Thus, it is important to fabricate a PBA framework with low defects



Page 12 of 26

and water content. Recently, Wang et al. reported a high Na concentration Na1.92FeFe(CN)6 with a rhombohedral structure, which delivered a high reversible capacity of 160 mAh/g and a high energy density of 490 Wh/kg,29 as shown in Figure 3a. The high Na concentration can overcome the Na-deficiency problem and reduce the water insertion. The inset of Figure 3a shows much flatter two-phase voltage profiles and sharper peaks, which indicates the first-order transition between these structures

during

the

charge/discharge.

Goodenough’s

group

reported

Na1.72MnFe(CN)6 with a reversible capacity of 134 mAh/g and high rate stability.30 The same group continued to remove interstitial H2O in the Na2MnFe(CN)6 framework either thermally or electrochemically.31 As shown in Figure 3b, the dehydrated Na2MnFe(CN)6 exhibited a reversible capacity of 150 mAh/g with flat plateaus at ~3.5 V; which delivered excellent rate capability and superior cycling performance with 75% capacity retention over 500 cycles. There are two synthesis methods for PBA: co-precipitation method and hydrothermal method. Recently, Novasis Energy Inc. have successfully synthesized Mn-based PBA with a quantity of 100 kg per batch (Figure 3c).32 They demonstrated that the synthesis of PBA was carried out by co-precipitation method based on a low temperature aqueous chemistry. A high-temperature calcination step is not needed, which can decrease the manufacturing cost and carbon emissions. The as-synthesized PBA exhibited excellent cycling stability with capacity retention ~90% after 700 cycles at 1.0 C (Figure 3d). The pouch cells with PBA cathode and hard carbon anode were also fabricated (Figure 3e). As shown in Figure 3f−h, the cell delivers both high


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

ACS Energy Letters

coulombic efficiency and capacity retention of 98.6% over 500 cycles at 1.0 C. Even at temperatures as low as −20 °C, 83% capacity can be maintained, which is higher than that of LiFePO4 under the same conditions in LIBs. Furthermore, the cells can deliver a good cycling life at an elevated testing temperature (Figure 3h). On the other hand, Cui et al.33 developed a symmetric Na-based open framework cell (Figure 3i), which was composed of a copper hexacyanoferrate (CuHCF) cathode and a manganese hexacyanoferrate (KMnHCMn) anode. This symmetric cell provided a specific energy of 27 Wh/kg at 1.0 C basis of the mass of the active materials. It showed nearly no capacity loss after 1000 cycles, which suggested its potential for practical applications. In summary, PBA are promising cathode candidates for commercial SIBs. However, the waste solutions resulting from the synthesis processes should also be taken into consideration because of the existence of toxic cyanide CN−.



Figure 3. (a) Galvanostatic charge/discharge curves of Na1.92FeFe(CN)6. Reprinted with permission from ref. 29. Copyright 2015 American Chemical Society. (b) Galvanostatic charge/discharge curves of the removal of H2O in Na2MnFe(CN)6 frameworks. Reprinted with permission from ref. 31. Copyright 2015 American Chemical Society. (c) Scale-up of PBA synthesis from 10 kg to 100 kg per batch. (d) Cycling performance of PBA cathode. (e-h) Pouch cells and corresponding performance at different conditions with PBA cathode and hard carbon anode. (c–h) Reprinted with permission from ref. 32. Copyright 2018 Wiley. (i) Symmetric open-framework cell schematic. Reprinted with permission from ref. 33. Copyright 2014 Nature Publishing Group.

Carbon Anodes. Recent research on anode materials is focusing on carbonaceous materials, alloy compounds, oxides and organic compounds. Among them, carbon-based anodes are considered as the most promising one in short term. In 2000,


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

ACS Energy Letters

Dahn et al. first reported the electrochemical Na storage behavior of hard carbon prepared by the pyrolysis of sucrose.34 As shown in Figure 4a, a high reversible capacity of 300 mAh/g can be obtained with two distinct regions: a sloping region and a low-voltage plateau region. To date, efforts have been paid to further enhance the reversible capacity of hard carbon through structural investigation. Hasegawa et al. reported that hard carbon structure depended on the synthesis conditions.35 They explored the relationship between physical properties and electrochemical performance via controlling the carbonization temperature from 800 to 3000 °C. As shown in Figure 4b, hard carbon carbonized at 1600−2500 °C delivered the highest capacity with an initial Coulombic efficiency over 90%. The choice of carbon precursor is another key issue. As shown in Table 1, hard carbon showed reversible capacities mainly from 280 to 330 mAh/g and exhibited high initial Coulombic efficiency when the surface area is low. Among various carbon precursors, pitch mixture and biomass as well as biomass waste are attractive for large-scale applications due to their low cost and relatively high carbon yield. Hu et al. reported a coal derived hard carbon.36 With such hard carbon anodes, a prototype Na pouch cell was fabricated (Figure 4c), which exhibited a practical energy density of 100 Wh/kg (Figure 4d, e). Kuraray Co. Ltd. has also produced hard carbon from biomass using various temperatures.37 As shown in Figure 4f, the carbon material delivered a reversible capacity about 280 mAh/g and a high initial Coulombic efficiency of ~90%. There has been speculation that hard carbon anodes in SIBs exhibit poor rate



Page 16 of 26

capability. Recent work showed that this is caused by the poorly designed half-cell test protocol.38 The rigid 0 V cut-off voltage together with the sensitivity of the hard carbon capacity against polarization cause premature truncation of the sodiation process of the hard carbon anode, which would be negligible in full-cells. In work of Zheng et al.,38 the full-cell cycled 1300 times (2020 hours) at 1.0 C before the capacity retention hit 70%, whilst the half-cell with the same anode survived no more than 100 hours with low capacity retention. This indicates that hard carbon itself could serve as a high rate anode material.

Table 1. Electrochemical performance comparison of hard carbon anodes derived from various precursors. Precursor

Temperature (°C)

Capacity (mAh/g)

Surface area (m2/g)

Initial Coulombic efficiency (%)

~ 8.7

78 86.4

27 8 ~

88 82 80

1.3 ~

82 81

Commercial hard carbons Carbotron P(J) (Kureha) Type-2 (Kurary)37

39

~ ~

240 280 Biomass/Biomass waste

34

Glucose Sucrose40 Wood41

1100 1400 1100

307 311 295 Pitch mixture

42

Pitch/lignin Coal36

1400 1200

254 222

Rational designing of a hard carbon anode for Na storage is the pursuit of many


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

ACS Energy Letters

groups. Unfortunately, the Na storage mechanism is still not clear and some controversies still exist. Dahn et al. pointed out that the sloping and plateau regions correspond to the insertion of Na+ into the graphene layers and the adsorption of Na+ in the nanopores of hard carbon, respectively (Figure 4g).34 Ji et al. proposed that the sloping part of the potentiogram curve can be better explained through storage at defect sites, and the low voltage plateau region resulted from the intercalation between graphene sheets, as well as minor phenomenon of Na adsorption on pore surfaces (Figure 4h).40 Recently, Hu’s group found that the sloping region corresponds to adsorption of Na in defected sites, edges, and the surface of nanographitic domains while the plateau region is contributed to the nanovoids filling (Figure 4i).43 Xiao et al.44 reported that the in-plane defects on the nano-sections of graphene are tunable by means of the temperature increasing rate during the pyrolysis process. Low temperature-increasing rate would induce less defect concentration in hard carbon, thus resulting in higher reversible specific capacity.



Figure 4. (a) Voltage profiles of glucose pyrolyzed hard carbon anodes (1000 and 1150 °C). Reprinted with permission from ref. 34. Copyright 2000 the Electrochemical Society. (b) Discharge/charge curves of hard carbon anodes obtained with carbonization temperature ranging from 1200 to 2500 °C. Reprinted with permission from ref. 35. Copyright 2015 Wiley. (c-e) The schematic and performance of pouch cells. (c–e) Reprinted with permission from ref. 36. Copyright 2016 Elsevier. (f) Initial discharge/charge profiles of commercially available hard carbon anode from Kuraray Co. Ltd. Na ion storage mechanism of hard carbon anode: (g) “Intercalation– adsorption” mechanism. (h) “Adsorption–intercalation” mechanism. Reprinted with permission from ref. 40. Copyright 2015 American Chemical Society. (i) “Absorption-filling” mechanism of hard carbon anode for Na ion storage. Reprinted with permission from ref. 43. Copyright 2016 Wiley.

Summary and Future outlook. In this perspective, we focus on the development of electrode materials with low-cost, environment-friendly, and high performance for


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

ACS Energy Letters

SIBs. Layered metal oxides, polyanoinic compounds and PBA possess the most promising application prospects because of their acceptable cycling performance and energy density. The Co- and Ni-free layered metal oxides are the suitable cathode candidates for low-cost SIBs, but the structural and moisture stability still need to be improved for practical applications. The introduction of extra cations, such as Al3+, Cu2+, Mg2+, Mn4+, Ti4+ etc. into the transition metal layers is an effective strategy to improve the cycling performance by suppressing the irreversible phase transitions and enhancing the air stability. Polyanoinic compounds can provide higher voltage, but optimization on reducing the particle size and carbon coating is usually needed to improve its relatively poor electron conductivity. Another type of cathode, PBA, also shows good electrochemical performance due to abundant redox-active sites and strong structural stability. Among all PBA materials, Mn-based and Fe-based PBA frameworks exhibit the advantages for practically viable nonaqueous SIBs due to its low-cost, low environmental impact, and high electrochemical performance. However, the suitable synthesis methods are critical. Compared with their organic electrolyte counterparts, aqueous SIBs (ASIBs) with high rate capability, strict safety, long cyclability, and low-cost can fulfill the requirements of large-scale EES applications. A comparison of ASIBs and lead-acid battery for energy-storage is shown in Table 2. Here ASIBs using NaxCuFe(CN)6 as cathodes and NaTi2(PO4)3/C as anodes would be a choice for large-scale stationary storage to substitute lead-acid batteries. Unfortunately, the current development of aqueous NaxCuFe(CN)6 cathodes is still in its early stage. Therefore, it is crucial to



Page 20 of 26

improve the performance of NaxCuFe(CN)6 by tailing the synthesis conditions.

Table 2. Comparison of ASIBs and lead-acid batteries for energy storage.

Cell components

Cell properties

ASIBs

Lead-acid batteries

Cathode

Layered metal oxides or PBA

PbO2

Anode

C@NaTi2(PO4)3

Pb

Separator

Synthetic cotton separator

Grass fiber

Electrolyte

Alkali-ion salt-water electrolyte

4 ~ 7 M H2SO4

Voltage

~2V

1.5 ~ 2 V

Energy density

25 ~ 35 Wh/Kg

20 ~ 40 Wh/Kg

Toxicity

ASIBs are made from non-toxic materials. They are safe to install in home or business, and in close proximity to people.

Lead metal, which composes over 70% of the weight of a lead-acid battery, is a known carcinogen.

Caustic

ASIBs use a saltwater-based, Sulfuric acid electrolyte is neutral-PH electrolyte. caustic and harmful to skin.

Safety

Spill prevention

ASIBs sealed.

are

completely Flooded lead acid batteries have the risk of jar leakage. Lead-acid batteries are installed in either 2 V or 12 V increments, which must be connected with each other to reach the target voltage. If a single failure will destroy the whole system.

Redundancy

ASIBs can be built at 48 V nominal. To improve energy of a system more batteries are put in parallel. If a single battery fails, the system still functions.

Temperature

ASIBs can operate from The corrosion rate of positive −5 °C to 40 °C without any plates double for every 10 °C negatively impact the life of rise in temperature. batteries.

Deep discharge cycle life

150 ~ 350 cycles charged at Exceed 2000 and 3500 100% DOD; cycles discharge at 100% 250 ~ 300 cycles charged at and 70% DOD, respectively. 70% DOD

Characteristics

Regarding to the anode side, hard carbon is the most promising choice in near term. Exploring methods for producing hard carbon using low-cost precursors with


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

ACS Energy Letters

high yield is important for manufacturing. Understanding of solid electrolyte interphase (SEI) between anodes and electrolytes needs to be improved to obtain higher initial Columbic efficiency and decrease the self-discharge of hard carbon for practical application. On the electrolyte side, electrolyte design and functional development is very critical. In general, NaClO4 and NaPF6-containing carbonated based electrolytes are widely used. The lower purity NaPF6 salt may lead to poor electrochemical performance while NaClO4-based electrolytes relate to its safety concerns. Thus, the development of high purity NaPF6 is required. Up to now, some academic and industrial organizations have provided a series of commercialized prototypes of SIBs. Recently, over 5.0 kWh of prototype Na-ion pouch cells were fabricated with layered metal oxide cathode and hard carbon anode by Faradion Co. Ltd.45 In 2015, CNRS and RS2E46 launched their first commercial cylindrical 18650 SIBs, which offered a life span of over 2000 cycles with an energy density of 90 Wh/kg. CNRS further fabricated a new start-up named “Tiamat” with polyanionic cathode and hard carbon anode.47 Recently, new SIB prototypes using Prussian white as cathode and hard carbon as anode have also been developed by Altris.48 For ASIBs, Aquion Energy Co. Ltd.49 produced its first aqueous hybrid ion battery using a manganese oxide cathode, a C@NaTi2(PO4)3 anode, and a saltwater and synthetic cotton separator. In 2015, the first production line of ASIBs was built by Enpower Energy Corp.50 in China. We believe that low-cost and high-performance SIBs will play an important role in the future grid energy storage system.



AUTHOR INFORMATION E-mail: [email protected]; [email protected]; [email protected] Notes The authors declare no competing financial interest. Biographies Yangyang Huang is now a Ph.D. candidate in the School of Materials Science and Engineering at Tongji University. His research mainly focuses on materials for sodium-ion batteries and solid-state lithium batteries. Yuheng Zheng is a postdoctoral researcher in the School of Materials Science and Engineering at Tongji University. He received his Ph.D. in Frontier Institute of Science and Technology, Xi'an Jiaotong University. He focused on low cost and long-life electrode materials for sodium-ion batteries, lithium metal anode and other techniques for electrochemical energy storage systems. Xiang Li is a postdoctoral researcher in the School of Materials Science and Engineering at Tongji University. He obtained his Ph.D. degree in 2018 from Huazhong University of Science and Technology. His research focuses on metal oxides and phosphates for Li-ion and Na-ion batteries. Felix Adams is an undergraduate Materials Science and Engineering student at the University of Maryland College Park. He is interested in learning more about new forms of sustainable energy storage. Wei Luo is a Professor in the School of Materials Science and Engineering at Tongji University. He received his Ph.D. from Huazhong University of Science and Technology in 2012. Prior to his current position, Luo worked as a postdoctoral researcher at Oregon State University (2012–2014), and University of Maryland (UMD, 2014–2016), before being promoted to Assistant Research Professor at UMD (2016–2017). His research interests include energy storage and conversion devices, biomass materials, and low-dimensional nanomaterials. Yunhui Huang received his Ph.D. from Peking University in 2000. From 2004 to 2007, he worked with Prof. John Goodenough in the University of Texas at Austin. In 2008, he became a Chair Professor of materials science in Huazhong University of Science and Technology. He is now the Director of the Institute of New Energy for Vehicles in Tongji University. His research group works on rechargeable batteries for energy storage and their electrode materials. http://nev.tongji.edu.cn/. Liangbing Hu is an associate professor at University of Maryland College Park. His research interests include nanomaterials and nanostructures, roll-to-roll nanomanufacturing, energy storage focusing on solid-state batteries and Na ion


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

ACS Energy Letters

batteries, and printed electronics. He is the (founding) director of the Center for Advanced Renewable Biomaterials (CARB) at the University of Maryland College Park (www.carb.umd.edu). He is also the co-founder of Inventwood, Inc. with efforts to further commercialize nanocellulose-based nanotechnologies. https://www.bingnano.com/.

ACKNOWLENDGEMNTS We are grateful for the financial support by National Key R&D Program of China (No. 2018YFB0905400), the National Natural Science Foundation of China (No. 51632001), and the project of Innovative Group of Guangdong Province (No. 2014ZT05N013). REFERENCES (1). Chen, K. S.; Balla I.; Luu, N. S.; Hersam, M. C. Emerging Opportunities for Two-Dimensional Materials in Lithium-Ion Batteries. ACS Energy Lett. 2017, 2, 2026−2034. (2). Dunn, B.; Tarascon, J M. Electrical Energy Storage for the Grid A Battery of Choices. Science 2011, 334, 928−935. (3). Abundance of Elements in Earth's Crust. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust.(accessed: Marcy 2018) (4). Luo, W.; Shen, F.; Bommier, C.; Zhu, H. L. Ji, X. L.; Hu, L. B. Na-Ion Battery Anodes: Materials and Electrochemistry. Acc. Chem. Res. 2016, 49, 231−240. (5). Choi, J. W.; Aurbach, D. Promise and Reality of Post-Lithium-Ion Batteries with High Energy Densities. Nat. Rev. Mater. 2016, 1, 16013−16029. (6). Vaalma, C.; Buchholz, D.; Weil, M.; Passerini, S., A Cost and Resource Analysis of Sodium-Ion Batteries. Nat. Rev. Mater. 2018, 3, 18013. (7). Delmas, C.; Fouassier, C. Hagenmuller, P. Structural Classification and Properties of the Layered Oxides. Physica B+C 1980, 99, 81−85. (8). Wang, P. F.; Yao, H. R.; Liu, X. Y.; Zhang, J. N.; Gu, L.; Yu, X. Q.; Yin, Y. X.; Guo, Y. G., Ti-Substituted NaNi0.5Mn0.5−xTixO2 Cathodes with Reversible O3−P3 Phase Transition for High-Performance Sodium-Ion Batteries. Adv. Mater. 2017, 29, 1700210. (9). Wang, P. F.; Guo, Y. J.; Duan, H.; Zuo, T. T.; Hu, E.; Attenkofer, K.; Li, H.; Zhao, X. S.; Yin, Y. X.; Yu, X.; Guo, Y. G., Honeycomb-Ordered Na3Ni1.5M0.5BiO6 (M = Ni, Cu, Mg, Zn) as High-Voltage Layered Cathodes for Sodium-Ion Batteries. ACS Energy Lett. 2017, 2, 2715−2722. (10). Wang, P. F.; Yao, H. R.; Liu, X. Y.; Yin, Y. X.; Zhang, J. N.; Wen, Y.; Yu, X.; Gu, L.; Guo, Y. G., Na+/Vacancy Disordering Promises Hgh-Rate Na-Ion Batteries. Sci. Adv. 2018, 4. eaar6018. (11). Wang, P. F.; You, Y.; Yin, Y. X.; Guo, Y. G., An O3-type NaNi0.5Mn0.5O2 Cathode for Sodium-Ion Batteries with Improved Rate Performance and Cycling Stability. J. Mater. Chem. A 2016, 4, 17660−17664.



(12). Yabuuchi, N.; Kajiyama, M.; Iwatate, J.; Nishikawa, H.; Hitomi, S.; Okuyama, R.; Usui, R.; Yamada, Y.; Komaba, S. P2-Type Nax[Fe1/2Mn1/2]O2 Made from Earth-Abundant Elements for Rechargeable Na Batteries. Nat. Mater. 2012, 11, 512−517. (13). Wang, P. F.; You, Y.; Yin, Y. X.; Guo, Y. G., Layered Oxide Cathodes for Sodium-Ion Batteries: Phase Transition, Air Stability, and Performance. Adv. Energy Mater. 2017, 8, 1701912. (14). Wang, P. F.; You, Y.; Yin, Y. X.; Wang, Y. S.; Wan, L. J.; Gu, L.; Guo, Y. G., Suppressing the P2–O2 Phase Transition of Na0.67Mn0.67Ni0.33O2 by Magnesium Substitution for Improved Sodium-Ion Batteries. Angew. Chem. Int. Ed. 2016, 55, 7445−7449. (15). Talaie, E.; Duffort, V.; Smith, H. L.; Fultz, B.; Nazar, L. F. Structure of the High Voltage Phase of Layered P2-Na2/3-z[Mn1/2Fe1/2]O2 and the Positive Effect of Ni Substitution on Its Stability. Energy Environ. Sci. 2015, 8, 2512−2523. (16). Han, M. H.; Gonzalo, E.; Sharma, N.; López del Amo, J. M.; Armand, M.; Avdeev, M.; et al. High-Performance P2-Phase Na2/3Mn0.8Fe0.1Ti0.1O2 Cathode Material for Ambient-Temperature Sodium-Ion Batteries. Chem. Mater. 2016, 28, 106−116. (17). Martinez De Ilarduya, J.; Otaegui, L.; López del Amo, J. M.; Armand, M.; Singh, G. NaN3 Addition, a Strategy to Overcome the Problem of Sodium Deficiency in P2-Na0.67[Fe0.5Mn0.5]O2 Cathode for Sodium-Ion Battery. J. Power Sources 2017, 337, 197−203. (18). Duffort, V.; Talaie, E.; Black, R.; Nazar, L. F. Uptake of CO2 in Layered P2-Na0.67Mn0.5Fe0.5O2: Insertion of Carbonate Anions. Chem. Mater. 2015, 27, 2515−2524. (19). Mu, L. Q.; Xu, S. Y.; Li, Y. M.; Hu, Y. S.; Li, H.; Chen, L. Q.; Huang, X. J. Prototype Sodium-Ion Batteries Using an Air-Stable and Co/Ni-Free O3-Layered Metal Oxide Cathode. Adv. Mater. 2015, 27, 6928−6933. (20). Wang, H.; Liao, X. Z.; Yang, Y.; Yan, X. M.; He, Y. S.; Ma, Z. F. Large-Scale Synthesis of NaNi1/3Fe1/3Mn1/3O2 as High Performance Cathode Materials for Sodium Ion Batteries. J. Electrochem. Soc. 2016, 163, A565−A570. (21). Deng, J.; Luo, W. B.; Lu, X.; Yao, Q.; Wang, Z.; Liu, H. K.; Zhou, H.; Dou, S. X. High Energy Density Sodium-Ion Battery with Industrially Feasible and Air-Stable O3-Type Layered Oxide Cathode. Adv. Energy Mater. 2017, 8, 1701610. (22). Barker, J.; Richaed, H. Doped Nickelate Materials. US Patent Application WO 2015/177556 A1, 2015. (23). Kendrick, E.; Robert, G. Layered Oxide Materials for Batteries. US Patent Application WO 2016/103649 A1,2016. (24). You, Y.; Manthiram, A., Progress in High-Voltage Cathode Materials for Rechargeable Sodium-Ion Batteries. Adv. Energy Mater. 2017, 8, 1701785. (25). Park, Y. U.; Seo, D. H.; Kim, H.; Kim, J.; Lee, S.; Kim, B.; Kang, K. A Family of High-Performance Cathode Materials for Na-Ion Batteries, Na3(VO1−xPO4)2F1+2x (0 ≤ x ≤ 1): Combined First-Principles and Experimental Study. Adv. Functional Mater. 2014, 24, 4603−4614.


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

ACS Energy Letters

(26). Bianchini, M.; Xiao, P.; Wang, Y.; Ceder, G. Additional Sodium Insertion into Polyanionic Cathodes for Higher-Energy Na-Ion Batteries. Adv. Energy Mater. 2017, 7, 1700514. (27). Ellis, B. L.; Makahnouk, W. R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. A Multifunctional 3.5 V Iron-Based Phosphate Cathode for Rechargeable Batteries. Nat. Mater. 2007, 6, 749−53. (28). Barpanda, P.; Oyama, G.; Nishimura, S. i.; Chung, S. c.; Yamada, A. A 3.8-V Earth-Abundant Sodium Battery Electrode. Nat. Commun. 2014, 5, 4358. (29). Wang, L.; Song, J.; Qiao, R. M.; Andrew Wray, L.; Hossain, M. A.; Chuang Y. D.; et al. Rhombohedral Prussian White as Cathode for Rechargeable Sodium-Ion Batteries. J. Am. Chem. Soc. 2015, 137, 2548−2554. (30). Wang, L.; Lu, Y. H.; Liu, J. Xu, M. W.; Cheng, J. G.; Zhang, D. W.; Goodenough, J. B. A Superior Low-Cost Cathode for a Na-Ion Battery. Angew. Chem. Int. Ed. 2013, 52, 1964−1967. (31). Song, J.; Wang, L.; Lu, Y. H.; Liu, J.; Guo, B. K.; Xiao, P. H.; Lee, J. J.; Yang, X. Q.; Henkelman, G.; Goodenough, J. B. Removal of Interstitial H2O in Hexacyanometallates for a Superior Cathode of a Sodium-Ion Battery. J. Am. Chem. Soc. 2015, 137, 2658−2664. (32). 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, 0, 1702869. (33). Pasta, M.; Wessells, C. D.; Liu, N.; Nelson, J.; McDowell, M. T.; Huggins, R. A.; Toney, M. F.; Cui, Y. Full Open-Framework Batteries for Stationary Energy Storage. Nat. Commun. 2014, 5, 3007−3016. (34). Stevens, D. A.; Dahn, J. R. High Capacity Anode Materials for Rechargeable Sodium-Ion Batteries. J. Electrochem. Soc. 2000, 147, 1271−1273. (35). Hasegawa, G.; Kanamori, K.; Kannari, N.; Ozaki, J. i.; Nakanishi, K.; Abe, T. Hard Carbon Anodes for Na-Ion Batteries: Toward a Practical Use. ChemElectroChem 2015, 2, 1917−1920. (36). Li, Y. M.; Hu, Y. S.; Qi, X. G.; Rong, X. H.; Li, H.; Huang, X. J.; Chen, L. Q. Advanced Sodium-Ion Batteries Using Superior Low Cost Pyrolyzed Anthracite Anode: towards Practical Applications. Energy Storage Mater. 2016, 5, 191−197. (37). http://www.kuraray.com. (accessed: March 2018) (38). Zheng, Y. H.; Wang, Y. S.; Lu, Y. X.; Hu, Y. S.; Li, J. A High-Performance Sodium-Ion Battery Enhanced by Macadamia Shell Derived Hard Carbon Anode. Nano Energy 2017, 39, 489−498. (39). New Products. http://www.kureha.co.jp. (accessed: March 2018) (40). Bommier, C.; Surta, T. W.; Dolgos, M.; Ji, X. New Mechanistic Insights on Na-Ion Storage in Nongraphitizable Carbon. Nano Lett. 2015, 15, 5888−5892. (41). Smith, A. J.; MacDonald, M. J.; Ellis, L. D.; Obrovac, M. N.; Dahn, J. R. A Small Angle X-Ray Scattering and Electrochemical Study of the Decomposition of Wood during Pyrolysis. Carbon 2012, 50, 3717−3723. (42). Li, Y. M.; Hu, Y. S.; Li, H.; Chen, L. Q.; Huang, X. J. A Superior Low-Cost Amorphous Carbon Anode Made from Pitch and Lignin for Sodium-Ion Batteries. J.



Mater. Chem. A 2016, 4, 96−104. (43). Li, Y. M.; Hu, Y. S.; Titirici, M. M.; Chen, L. Q.; Huang, X. J. Hard Carbon Microtubes Made from Renewable Cotton as High-Performance Anode Material for Sodium-Ion Batteries. Adv. Energy Mater. 2016, 6, 1600659. (44). Xiao, L. F.; Lu, H. Y.; Fang, Y. J.; Sushko Maria, L.; Cao, Y. L.; Ai, X. P.; Yang, H. X.; Liu, J. Low-Defect and Low-Porosity Hard Carbon with High Coulombic Efficiency and High Capacity for Practical Sodium Ion Battery Anode. Adv. Energy Mater. 2018, 0, 1703238. (45). Sodium-Ion Technology. http://www.faradion.co.uk/applications/stationary-energy-storage/.(accessed: May 2018) (46). A Promising New Prototype of Battery. http://www2.cnrs.fr/sites/en/fichier/cpbattery_vh.pdf. (accessed: March 2018) (47). A Start-Up for much Faster Batteries. http://www2.cnrs.fr/sites/en/fichier/cp_tiamat_vf_en_1.pdf. (accessed: May 2018) (48). A "Drop-in" Solution. http://www.altris.se/technology/. (accessed: May 2018) (49). Redefining Energy Storage http://aquionenergy.com/company/overview. (accessed: March 2018) (50). 1-2-3 Energy Solutions. http://www.enpowerenergy.com/home-e. (accessed: March 2018)

Selected Quotes 1. The key issue for SIBs towards large-scale storage applications is to search for suitable electrode materials with characteristics of high performance, low-cost, abundance, environment-friendly, long-term cyclability, and high safety. 2. Cathode materials, such as Mn- and Fe-based layered metal oxide, Fe-based polyanoinic compounds and Fe-Mn based PBA possess promising application prospects, while hard carbon derived from biomass or pitch mixtures as anode is the best choices for SIBs in current stage.


Page 26 of 26

A Perspective on Electrode Materials of Sodium-ion Batteries towards

Recommend Documents