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High voltage Li-ion battery using exfoliated graphite/Graphene nanosheets anode Marco Agostini, Sergio Brutti, and Jusef Hassoun ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b01407 • Publication Date (Web): 07 Apr 2016 Downloaded from http://pubs.acs.org on April 11, 2016

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ACS Applied Materials & Interfaces

High voltage Li-ion battery using exfoliated graphite/graphene nanosheets anode Marco Agostini1, Sergio Brutti2 and Jusef Hassoun3* 1

Sapienza University of Rome, Chemistry Department, Piazzale Aldo Moro 5, 00185, Rome, Italy 2

3

Dipartimento di Scienze, Università della Basilicata, Potenza, Italy

University of Ferrara, Department of Chemical and Pharmaceutical Sciences, Via Fossato di Mortara 17, 44121, Ferrara, Italy *Corresponding author: [email protected]

Keywords Graphene; graphite; anode; high-voltage; lithium-ion battery Abstract The achievement of a new generation of lithium-ion battery, suitable for a continuously growing consumer electronic and of sustainable electric vehicle markets, requires the development of new, low-cost and highly performing materials. Herein, we propose a new and efficient lithium-ion battery obtained by coupling exfoliated graphite/graphene nanosheets (EGNs) anode and highvoltage, spinel-structure cathode. The anode shows a capacity exceeding by 40% that ascribed to commercial graphite in lithium half-cell, at very high c-rate, due to its particular structure and morphology as demonstrated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and by transmission electron microscopy (TEM). The Li-ion battery shows excellent efficiency and cycle life, extending up to 150 cycles, as well as an estimated practical energy density of about 260 Wh Kg-1, that is, a value well exceeding the one associated to the present-state Li-ion battery. Introduction Continuous evolution of the consumer electronic market, recent growth of hybrid electric and full electric vehicles production, as well as the need for side systems suitable for renewable-sources grid

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stabilization, triggered increasing interest on new, high performances energy storage systems. Lithium-ion battery based on intercalation chemistry, so far considered an efficient power supply for electronic devices, needs further improvement and new materials, characterized by high energy content, in order to meet the new market severe targets.1-4 High energy systems, such as lithiumsulfur and lithium-oxygen batteries, have been proposed as suitable candidates for advanced applications.5-8 However, safety issues due to the presence of lithium metal at the anode side as well the need of further optimization of these promising systems still hinder their practical application.9 Recent advances have been achieved by replacing the conventional electrolytes by suitable media ensuring safe cell operation and satisfactory cycle life. Among the most promising electrolytes, polymers,10-12 inorganic glasses13-15 and ionic liquids16-18 actually show non-flammability and high stability against lithium metal anode, however they still suffer by low ionic conductivity and high resistance at the electrode/electrolyte interface.19-22 Commercial graphite-based electrode, commonly used as anode in lithium ion-battery, operates following the intercalation process Li + 6C = LiC6 and delivers a theoretical capacity limited to 372 mAh g-1. Lithium-metal alloys, such as Li-Sn23-25 and Li-Si,26-32 are considered promising anodes for battery application in view of their high theoretical capacity, i.e. 990 mAh g-1 and 4200 mAh g-1, respectively23-32 However, these electrodes suffer by limited cycle life due to the large volume variation induced by the Li-alloying process, and consequent mechanical stresses leading to material pulverization during cell operation. Several kind of carbon-based electrodes have been investigated for application in lithium ion battery, including graphite33 amorphous carbon34-35 and graphene36-38 In particular, graphene-based electrodes evidenced very promising electrochemical behavior as negative electrodes, thus suggesting these materials as alternative to commercial graphite. Yoo et al. developed an electrode able to deliver a stable capacity ranging between 650 to 400 mAh g-1 36 while Guo et al. prepared crumpled-paper-shaped graphene nanosheets with a capacity of 650 mAh g-1

37

and an excellent

cycling stability. Lian and coworkers demonstrated that few curled layer of graphene deliver a reversible capacity of about 800 mAh g-1 for 40 cycles using a current of 100 mA g-1.38 Graphene ACS Paragon Plus Environment

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may theoretically store higher lithium amount in comparison to graphite, thus leading to a theoretical specific capacity ranging from 744 mAh g-1 to 1448 mAh g-1, depending on the particular graphene-based electrode morphology.37-42 Indeed, lithium may bond both graphene sheet sides as well as edges and covalent sites.36 Accordingly, recent studies demonstrated that the small lateral sizes of narrow graphene nano-ribbons (e.g. nanoflakes), can actually accommodate Li+ ions at the edges sites more efficiently than basal sites,42 thus leading to maximum Li-storage of Li4C6 with corresponding theoretical specific capacity of 1488 mAh g-1. Despite of these excellent performances in Li-half cells, only few Li-ion cells using graphene electrode has been reported,39-41 due to issues hindering its practical use such as the huge initial irreversible capacity, the limited cycle life and the very low loading.39-41 In particular, H. Sun and all recently reported a binder-free graphene electrode in a full lithium-ion battery employing a spinel-structure cathode , however characterized by limited cycling performance (i.e., 30 cycles) and poor capacity (about 100 mAh g1 40

).

Herein, we report a Cu-supported, binder-free anode based on exfoliated graphite/graphene

nanosheets (EGNs) prepared by a simple technique consisting in ultra-sonication and ultracentrifugation of graphite-based solution. The EGNS electrode, proposed as anode for lithium-ion battery, delivers a very stable capacity exceeding that of commercial graphite. Indeed, the Li/EGNs half-cell shows a capacity of about 500 mAh g-1 at high current rate for over 400 cycles. The EGNs anode is efficiently combined with LiNi0.5Mn1.5O4 high-voltage cathode in a full, lithium-ion battery characterized by enhanced cycle life and energy density.

Experimental Exfoliation of-the bulk graphite. The Graphene-ink solution is prepared by dispersing 200 mg of Graphite (Timcal, Timrex) in 20 mL of N-Methyl-2-Pyrrolidone (NMP, Sigma Aldrich Ltd.). The dispersion is then subjected to ultra-sonication, to allow graphite exfoliation43,44 performed for 6 hours at a frequency of 60 Hz in a water bath by using continuous batch mode (2 steps of 3 hours and 10 min of rest) and following ultra-centrifugation using a PK 131R Centrifuge at 10000 rpm for ACS Paragon Plus Environment


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60 minutes. During ultra-centrifugation, the graphitic dispersion is separated into two fractions, one containing the smaller particles (top-side solution, carbon concentration ∼ 50 mg/L) and the other containing the larger particles (bottom-side solution, carbon concentration ∼ 2 g/L). The carbon concentration was determined by Thermo-gravimetric analysis (TGA; SDTA 851 Mettler-Toledo) performed within temperature ranging between 25°C and 800 °C, using a scan rate of 10 °C/min and under Air atmosphere. The second solution, characterized by the higher carbon concentration, has been used for exfoliated graphite/graphene nanosheets electrode preparation (indicated by the acronym EGNs). The electrodes are prepared by drop-wise casting of the carbon-ink solution onto a 10 mm of diameter Cu-support and following drying, with a final loading of about 1 mg cm-2. The as prepared electrodes were dried at 200 °C under vacuum to remove residual solvents. The LiNi0.5Mn1.5O4 cathode. Lithium nickel-manganese spinel (LiNi0.5Mn1.5O4) was obtained following a wet chemistry route, by mixing in a stoichiometric ratio and dissolving in water LiNO3, Ni(NO3)2·H2O, and Mn(NO3)2·H2O. The mixture was finally dried and annealed in air at 800 °C for 24 hours and slowly cooled (0.5 °C/min of rate) to room T. The material has a structure well defined by a spinel phase (JCPDS 802162) while the morphology is micrometric (∼5 µm) .45 Electrochemical characterization. Li/EGNs half-cell and the EGNs/LiNi0.5Mn1.5O4 full-cell were assembled by using a Watman® glass fiber imbibed by LP30 (EC:DMC 1:1 v/v, LiPF6 1M) electrolyte solution in a polypropylene T-type cell. The Li/EGNs cell was galvanostatically cycled using a current of 744 mA g-1 (corresponding to 2C for a typical graphite)33 within 0.01V and 3.0V. The Cyclic Voltammetry (CV) tests were performed using a three electrode polypropylene T cell configuration, with Li foil as reference and counter electrode while LP30 (EC:DMC 1:1 v/v, LiPF6 1M) was used as electrolyte. The tests were run with a scan rate of 0.05 mV s-1, in the voltage ranging between 0.01V and 3V, using a VSP Biologic instrument. The EGNs anode has been precycled in Li/EGNs cell using a current of 744 mAh g-1 and a voltage ranging between 0.01V and 3 V for 5 cycles. The LiNi0.5Mn1.5O4 electrode has been pre-cycled in a Li-half cell by using a current


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of 120 mA g-1 (considered as the practical 1C current) and a voltage ranging between 4.9 and 2.5 V for 5 cycles. After pre-cycling, the half cells at the discharged state have been disassembled and the EGNs and LiNi0.5Mn1.5O4 coupled in full cell. The full cell was prepared by selecting a 1:4 anode to cathode mass ratio. Basing on the capacity delivered by the cathode (about 125 mAh g-1) and the one delivered by the anode (about 500 mAh g-1), the mass ratio leads to a practical Negative to Positive (N/P) ratio of about 1. Considering a lower delivered cathode capacity (of about 120 mAh g-1) the N/P ratio becomes 1.04. Hence, the optimal N/P ratio should be comprised in between 1 and 1.05. The Li-ion cell was cycled within 2.5V and 4.7V range using a 120 mA g-1 current (as referred to the LiNi0.5Mn1.5O4 cathode weight). After 15 stabilization cycles performed at 1C, the EGNs/LNMO Li-ion cell was also cycled at a current rate increasing from 1C to 5C (1C=120 mA g1

) within 2.5V and 4.8V voltage range.

X-ray diffraction. The XRD measurement was carried out by using a Rigaku D-max with Cu Kα radiation source in a 2θ range between 10-90 degrees. Electron microscopies. Scanning electron microscopy images (SEM) have been taken by using a Phenom FEI instrument. Transmission electron microscopy (TEM) images have been recorded by using a FEI G2 20 HR-TEM instrument equipped with a LaB6 electron beam source and two 2D flat cameras (low resolution and high resolution) at 200kV e-beam acceleration. The NMP exfoliated graphite/graphene nanosheets suspension has been directly dispersed on copper holey carbon film grids for observation. The NMP solvent has been gently evaporated by heating the copper holey carbon films at 40-50°C degrees under vacuum before insertion into the microscope. Raman Spectroscopy. The Raman spectrum has been measured directly on a droplet of the NMPexfoliated graphite/graphene nanosheets suspension by a LabRam HR HORIBA Jobin Yvon spectrophotometer with a He-Ne (632.8 nm) laser source. The Raman spectrum of bulk graphite has been recorded on a cold-pressed pellet.



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Result and discussion The EGNs material is synthesized by direct exfoliating a graphite precursor. The pristine powder is dispersed in N-Methyl-2-Pyrrolidone (NMP), ultra-sonicated46 and following separated, via ultra-centrifugation, into two fractions characterized by high and low carbon-substrate loading, located in the top and bottom side of the centrifuge-vial, respectively.47 The top-side fraction is mainly composed by almost pure graphene substrate47 with a concentration of 50 mg/L. This fraction is not considered for battery application, due to the very low mass loading of the electrode prepared using it as the carbon precursor. Instead, the bottom-side fraction, having a carbon content of about 2 g/L, is used for electrode preparation. Figure 1 reports the Scanning Electron Microscopy (SEM) images collected for BG (a) and EGNs (b). BG shows a rather compact morphology typical of crystalline graphite33 instead EGNs evidences a remarkable dispersion and a lower material density, as most likely ascribed to the exfoliation by ultrasonic treatment. The Transmission Electron Microscopy (TEM) image of a sample collected from the latter fraction, reported in Figure 1c, evidences that the material is formed by layers of nanometric thickness (i.e., Nanosheets). Furthermore, the magnification of the TEM at particles edge (Figure 1d) suggests that the nanosheets overlap 8 to 12 graphene layers (3-5 nm), with an inter-layer distance of about 0.34 nm. This value, slightly larger than the (002) stacking of graphite, suggests increased in-plane and stacking disorders due to mechanical treatments (ultra-sonication) and consequent material exfoliation. This aspect has been further investigated by performing a comparative X-Ray Diffraction study using both bulk graphite powder (BG, Figure 1e red pattern) and the exfoliated graphite/graphene nanosheets (EGNs, Figure 1e blue pattern). The pattern of the BG shows six diffraction peaks, ascribed to crystalline graphite (JCPDS #75-2078), indexed by (002), (100), (101), (004), (110) and (105) reflections48 while the EGNs pattern shows only one peak of lower intensity (i.e., corresponding to the reflection 002). The reduction of the peak number and intensity suggests an increasing ratio of the amorphous phase within the EGNs sample. The analysis of the


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pattern area reveals rather high amorphous-phase degree, determined as difference between the total diffraction pattern area and the (002) peak area in Figure 1c (blue line).

(a)

(b)

(c)

(d)

002

G

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BG 10

Intensity / a.u.

EGNs Intensity / a.u.

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20

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60

Cu Kα 2θ / degree

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90

D+D' 2D'

EGNs G

-1

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2D(2684 cm ) 2D'

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BG 30

2D(2669 cm ) D'

105

110

004

-1

D

1000

1500 2000 2500 -1 Raman Shift / cm

(e)

3000

3500

(f)

FIGURE 1. Scanning Electron Microscopy (SEM) image of the BG (a) and of the EGNs (b). Transmission Electron Microscopy (TEM) images of the EGNs particles (c) and edge (d). X-ray diffraction patterns (e) and Raman spectra collected at 532 nm wavelength (f) of EGNs (blue lines) and the Bulk Graphite (BG, red lines). This value confirms the increasing disorder of the crystalline structure induced by the exfoliation process. However, crystallinity due to the presence of the exfoliated graphite can be still ACS Paragon Plus Environment


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observed. Raman spectroscopy has been employed to study the number of graphene layers, the defects ratio, the chemical modification and the carbon disorder degree of the EGNs. Figure 1f, reporting the spectra of EGNs (blue line) and, for comparison, of BG (red line), shows the appearance of the D’ and D+D’ peaks in the EGNs sample and highlights an increasing I(D)/I(G) ratio from 0.28 for pristine BG to 0.77 for exfoliated GNS, thus suggesting a carbon material with higher disorder in respect to the pristine precursor. Furthermore, the shift of the 2D-peak position of about 15 cm-1 suggests that EGNs is mainly formed by 5 to 10 graphene layers,49 in full agreement with the TEM image reported in Figure 1d. The Cu-supported EGNs electrode is investigated in terms of electrochemical performances in lithium half-cell, in comparison with a BG electrode.

Figure 2a reports the voltage profiles of the EGNs (blue line) and of the BG (red line) from 2nd to 10th cycle. The cycling tests have been performed using a current rate of 2C for the EGNs, while BG required a lower current rate, i.e., limited to 0.2C, in order to deliver satisfactory capacity (1C current was referred to bare graphite as 372 mA g-1). Both the electrodes reveal the typical intercalation/de-intercalation of Li+ within the graphite, characterized by a flat profile within the low voltage region, ranging from 0.25V to 0.01V.33 Additional Li-insertion slope, extending from 0.25V to 3.00V within the higher voltage region,41 is observed for the cell using the EGNs electrode (blue curve in Fig.2a). This shape, typically observed during Li-uptake into amorphous and graphene-type carbons34,35 allows for the EGNs electrode a capacity as high as 500 mAh g-1, while the BG, in which the additional slope is absent (compare with red curve in Fig.2a), reveals a capacity limited to about 300 mAh g-1. This aspect is further clarified by Figure 2b, reporting the CV comparison between the two electrodes at the steady state (see Figure S2 in Supporting Information reporting the 1st CV cycle). During the first cycle, Figure S2 shows the above mentioned process associated to the intercalation of the Li+ in the graphitic structure of carbonmaterials, occurring between 0.3V and 0.01V, and the irreversible process related to the formation of the Solid Electrolyte Interphase (SEI) at the carbon surface, centered at about 0.7 - 0.6V. As expected, the EGNs electrode shows the additional process occurring between 0.9V and 2.5V, ACS Paragon Plus Environment

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associated to the Li+ uptake in the graphene phase of the carbon-material and already observed in previous papers focusing on a carbon material with a high graphene ratio in its composition.41 3.0

Voltage / V

2.5

nd

2 to 10

BG

th

EGNs

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(a) 450 EGNs BG

Current / mA g

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300 150 0 -150 -300 Steady State Cycles -450 0.0

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1.0 1.5 2.0 2.5 + Potential vs Li / Li

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900 Specific Capacity / mAh g

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(c) FIGURE 2. Galvanostatic voltage profiles from 2nd to 10th cycle (a), comparison of cyclic voltammetry at the steady state (b) and of the galvanostatic cycling performance (c) between the EGNs (blue line) and the BG (red line). Voltage range 0.01V–3V. Galvanostatic current density in lithium half cell 474 µA cm-2 (corresponding to 2C for the EGNS and C/5 for the BG). Scan rate of the cyclic voltammetry in three electrodes lithium cell 0.05 mV s-1. Electrolyte LP30 (EC:DMC 1:1 v/v, LiPF6 1M). ACS Paragon Plus Environment


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The following, steady state CV profiles (Figure 2b) reveal the low voltage peaks both for BG and EGNs, while only the EGNs reveals the reversible Li+ reaction at the higher potentials. The SEM-TEM-Raman-XRD study of Figure 1 as well as the electrochemical tests of Figure 2 suggest a ratio of exfoliated graphite to graphene of approximately 65:35 w:w. It is well known that graphite electrochemically reacts with lithium following the mechanism: Li+6C ⇌ LiC6 (1) with a specific capacity of 372 mAh g-1 Instead, graphene, that may accommodate lithium in two sides of the carbon layer, electrochemically reacts following the mechanism:39,41 Li+3C ⇌ LiC3 (2) with a specific capacity of 744 mAh g-1 Taking into account the exfoliated graphite:graphene weight ratio in the GNSs (65:35) and the specific capacities of the reactions (1) and (2) we may calculate a theoretical specific capacity associated to the electrochemical process of about 500 mAh g-1 that is well in agreement with the value experimentally observed in Fig. 2a. The galvanostatic cycling response of Figure 2c evidences similar stability for the two electrodes, and a higher irreversible capacity during the first cycle of the cell using the EGNs (see Figure S1a in the Supporting Information section for the corresponding voltage profile), as expected by the presence at the electrode surface of additional functional groups, oxygen atoms, hydrogen atoms and impurities.50-52 However, the effect of the high specific surface area (SSA) of the EGNs in increasing its irreversible capacity during the first cycle cannot be excluded. According to BET data SSA of the BG is lower than 100 m2/g, while that of EGNs is one order of magnitude higher, i.e., higher than 1000 m2/g. This may be also deducted by the comparison of the SEM images of BG and EGNs reported in the Supporting Information section (Figure S3). This extra-capacity may be efficiently mitigated both chemically, i.e., by lithium-metal surficial treatment of the electrode and electrochemically by pre-cycling, as already demonstrated in previous reports.39,41 Figure 2c reveals ACS Paragon Plus Environment

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a capacity value about 40% higher for the EGNs electrode in respect to BG delivered, in addition, at higher current rate (i.e., 2C in respect to 0.2C). Indeed, the presence of graphene layers, the edge-

lithium storage and the particular morphology of the EGNs electrode allows the uptake an extra lithium amount41 in respect to BG, thus leading to a higher capacity and rate capability of the material here proposed, thus well compensating the relatively higher working voltage observed in Fig. 2a.

Figure 3 shows the prolonged electrochemical behavior of the EGNs electrode in lithium half-cell, at a current rate of 2C. The cell shows a stable capacity, ranging between 500 to 450 mAh g-1, up to 400 charge/discharge cycles, with a Coulombic efficiency exceeding 99 % at the steady state condition following the first cycle. 3.5

800

th

10 th 100 th 200 th 400

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500 400 300

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100

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0 0

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(a)

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(b)

FIGURE 3. Prolonged cycling performance (a) and corresponding voltage profiles during the 10th, 100th, 200th, 400th cycle (b) of the Li/EGNs half-cell using a current density of 744 mA g-1, within 0.010V and 3V. Electrolyte LP30 (EC:DMC 1:1 v/v, LiPF6 1M). This relevant performance suggests the Cu-supported, EGNs electrode here studied as very promising candidate for application in lithium ion battery. The excellent electrochemical properties of the EGNs electrode allowed its efficient employment in a full, lithium-ion cell in combination with a high voltage lithium nickel manganese spinel (LiNi0.5Mn1.5O4). The cathode material,



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characterized by a working voltage of about 4.8 V vs. Li, and a specific capacity of 148 mAh g1 24,43-45,53

,

is used in excess (i.e., following a 1:4 anode to cathode mass ratio) in order to achieve a

proper full-cell balance (with a N/P ratio of about 1.04). Indeed, the cathode weight takes into account the characteristics of EGNs in terms of capacity and working voltage values, thus leading an optimal Negative to Positive (N/P) ratio. This optimal condition, in addition to an enhanced electrodes configuration, leads to a higher capacity and prolonged cycle life of the cell, i.e., performances greatly improved in respect to previous literature works.40 In order to achieve fully reversible and efficient cycling, the two electrodes have been pre-cycled in lithium half-cell prior to full cell assembly. Figure 4 reports the voltage profiles (a) and the cycling behavior (b) of the EGNs/ LiNi0.5Mn1.5O4 lithium-ion cell studied a current rate of 120 mA g-1, as well as the cycling test performed at increasing C-rates (c). The battery operates at 3.8 V with a voltage profile reflecting the combination between the shape of the EGNs and of the LiNi0.5Mn1.5O4 electrodes, and a reversible capacity of about 125 mAh g-1, that is, of about 85% of the theoretical capacity of the cathode. During the first 10 to 15 cycles the cell shows a relatively low coulombic efficiency due to continuous growth of the SEI film at the electrode/electrolyte interface both at the anode and at the cathode sides, until stabilization with an increase of the coulombic efficiency. Following the initial few stabilization cycles, the cell shows a remarkable stability, exceeding 150 cycles, and a coulombic efficiency higher than 99 %. The steady state cell efficiency lower than 100% is due to limited excess of cell charging (about 1%) by slight electrolyte oxidation at the high voltage cathode and its contemporary reduction at the EGNs anode that leads only to SEI film growth at the two electrodes, without affecting the reversible capacity during the prolonged cycling, in particular considering a N/P ratio approaching 1 (see for further clarity the steady state cycle of a LiNi0.5Mn1.5O4 cathode and of a EGNs electrode in half cell in figure S4 in SI section).


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5.0

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current = 120 mA g Stable cycles

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(c) FIGURE 4: Galvanostatic test of the EGNs/LiNi0.5Mn1.5O4 lithium-ion battery performed at a current density of 120 mA g-1 within 2.5V and 4.7V, reported in terms of cycling behavior (a) and voltage profile (b) at the steady state condition. Electrolyte LP30 (EC:DMC 1:1 v/v, LiPF6 1M). (c) Cycling behavior during the rate capability measurement, performed at 1C (120 mA g-1, black), 2C (red), 3C (blue), 4C (green) and 5C (orange).



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The response of the cell at increasing C-rates reported in Figure 4c highlights a capacity ranging from about 125 mAh g-1 at the 1C (considered as 120 mA g-1) to about 50 mAh g-1 at 5C (600 mA g-1), that is reflecting into a remarkable power density ranging from 0.430 kW kg-1 at 1C to about 2.1 kW kg-1 at 5C (see corresponding voltage profiles reported in Figure S5 in Supporting Information).

Conclusion Graphene and graphene oxide-based anodes have been widely explored in lithium half-cell, revealing a stable capacity ranging between 800 to 300 mAh g-1.36-38 However, only few works demonstrated the suitability of this material in replacement of the Li-anode in Li-full cell.39-41 This is mainly due to the poor loading of graphene-based electrode that leads to severe issue during cell assembly and scaling up, mainly ascribed to very difficult N/P ratio setting. Herein we developed a EGNs electrode of satisfactory mass density leading to enhanced performance in half-cell, with reversible capacity of about 500 mAh g-1, as well as to successfully balanced full cell having remarkable cycle life and efficiency. The exfoliated graphite/graphene electrode differs from the graphene-based materials reported in literature for application in lithium-ion battery36-41 both in terms of lithium intercalation-uptake mechanism and in terms of mass loading. Indeed, the EGNs electrode electrochemically reacts with lithium following a hybrid mechanism, reflecting contemporary the intercalation into the graphite structure and the insertion within the graphenenanosheets. The EGNs electrode has been coupled with a high-voltage, LiNi0.5Mn1.5O4 cathode in a lithium-ion battery. The spinel-structure electrode has been selected due to the high working voltage, i.e. 4.8 V, and thus to the remarkable theoretical energy density (720 Wh kg-1).24,45,53 as well due to its suitability for full lithium-ion cell applications.54-56 The full cell efficiently operates at 3.8V with a specific capacity of about 125 mAh g-1, for more than 150 cycles. Basing on the cell characteristics, and taking into account a reduction factor of 1/3 to include the contribution of inert components to the overall cell weight, we estimated that the Li-ion battery here reported may


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deliver a practical energy density as high as 260 Wh Kg-1, i.e. exceeding by 30% the value ascribed to the commercial battery.1-4 These data demonstrate the applicability of the EGNs electrode, prepared by a scalable exfoliation-based synthesis, in a high performances battery. In summary, the EGNs electrode is characterized optimized electrochemical performances and suitable active material loading, i.e., unique characteristics leading to stable cycling both in high performance half cell and in efficient, full lithium ion cell. In addition, the EGNs is a binder-free material, simplify prepared by exfoliating the graphite in a solvent media and casting into Cu-support. This procedure may be, indeed, proposed as a scalable and low cost method for large-scale electrode fabrication. The outstanding characteristics of the EGNs electrode suggest it as suitable candidate for advanced energy storage systems.

Acknowledgments J.H. would thank a collaboration Project between Sapienza University of Rome, Chemistry Department and University of Ferrara, Department of Chemical and Pharmaceutical Sciences “Accordo di Collaborazione Quadro 2015”.

Supporting Information. Figure S1. Voltage profile at the 1st cycle for the EGNs and for the) LNMO in half lithium cell. Figure S2. Cyclic Voltammetry of the EGNs the BG electrodes in LP30 electrolyte. Figure S3. Comparison of the magnified SEM images of EGNs and BG. Figure S4. Cell balancing considered for a EGNs/LNMO the lithium ion battery. Figure S5. Voltage profiles during the rate capability measurement performed at 1C for the EGNs/LNMO lithium-ion cell

References [1] Tarascon, J.-M.; Armand, M. Issues and Challenges Facing Rechargeable Lithium Batteries.

Nature 2001, 414, 359–367.



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

[2] Scrosati, B.; Garche, J. Lithium Batteries: Status, Prospects and Future. J. Power Sources 2010,

195, 2419–2430. [3] Armand, M.; Tarascon, J.-M. Building Better Batteries. Nature 2008, 451, 652–657. [4] Scrosati, B. Challenge of Portable Power. Nature 1995, 373, 557–558. [5] Rauh, R.-D.; Abraham, K.-M.; Pearson, G.-F.; Surprenant, J.-K.; Brummer, S.-B. A Lithium/Dissolved Sulfur Battery with an Organic Electrolyte. J. Electrochem. Soc. 1979, 126, 523–527. [6] Peled, E.; Sternberg, Y.; Gorenshtein, A.; Lavi, Y. Lithium-Sulfur Battery: Evaluation of Dioxolane-based Electrolytes. J. Electrochem. Soc. 1989, 136, 1621–1625. [7] Abraham, K.-M.; Jiang, Z. A Polymer Electrolyte-based Rechargeable Lithium/Oxygen Battery.

J. Electrochem. Soc. 1996, 143, 1–5. [8] Bruce, P.-G.; Freunberger, S.-A.; Hardwick, L.-J; Tarascon, J.-M. LiO2 and Li-S Batteries with High Energy Storage. Nat. Mater. 2012, 11, 19–29. [9] Manthiram, A.; Fu, Y.; Su, Y.-S. Challenges and Prospects of Lithium-Sulfur Batteries. Acc.

Chem. Res. 2013, 46, 1125–1134. [10] Kim, G.T.; Appetecchi, G.B.; Carewska, M.; Joost, M.; Balducci; A.; Winter, M.; Passerini, S. UV Cross-Linked, Lithium-Conducting Ternary Polymer Electrolytes Containing Ionic Liquids. J.

Power Sources 2010, 195, 6130–6137. [11] Agostini, M.; Hassoun, J. A Lithium-Ion Sulfur Battery using a Polymer, Polysulfide-added Membrane. Sci. Rep. 2015, 5, 7591. [12] Tatsumisago, M.; Hayashi, A. Superionic Glasses and Glass–Ceramics in the Li2S–P2S5 System for All-Solid-State Lithium Secondary Batteries. Solid State Ionics 2012, 225, 342–345.


Page 16 of 22

Page 17 of 22

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


[13] Ito, S.; Fujiki, S.; Yamada, T.; Aihara, Y.; Park, Y.; Kim, T.Y.; Baek, S.-W.; Lee, J.-M.; Doo, S.; Machida, N. A Rocking Chair Type All-Solid-State Lithium Ion Battery Adopting Li2O–ZrO2 Coated LiNi0.8Co0.15Al0.05O2 and a Sulfide based Electrolyte. J. Power Sources 2014, 248, 943–950. [14] Agostini, M.; Aihara, Y.; Yamada, T.; Scrosati, B.; Hassoun, J. A Lithium-Sulfur Battery using a Solid, Glass-Type P2S5-Li2S Electrolyte. Solid State Ionics 2013, 244, 48–51. [15] Yamada, T.; Ito, S.; Omoda, R.; Watanabe, T.; Aiharaa, Y.; Agostini, M.; Ulissi, U.; Hassoun, J.; Scrosati, B. All Solid-State Lithium-Sulfur Battery using a Glass-Type P2S5-Li2S Electrolyte: Benefits on Anode Kinetics. J. Electrochem. Soc. 2015, 163, A646–A651. [16] Agostini, M.; Ulissi, U.; Di Lecce, D.; Ahiara, Y.; Ito, S.; Hassoun, J. A Lithium-Ion Battery based on an Ionic Liquid Electrolyte, Tin-Carbon Nanostructured Anode, and Li2O-ZrO2-Coated [LiNi0.8Co0.15Al0.05] O2 Cathode. Energy Technol. 2015, 3, 632–637. [17] Noda, A.; Abu Bin Hasan, S.; Kudo, K.; Mitsushima, S.; Hayamizu, K.; Watanabe, M. Brønsted Acid-Base Ionic Liquid as Proton-Conducting Nonaqueous Electrolytes. J. Phys. Chem. B

2003, 107, 4024–4033. [18] Fernicola, A.; Scrosati, B.; Ohno, H. Potentialities of Ionic Liquids as New Electrolyte media in Advanced Electrochemical Devices. Ionics 2006, 12, 95–102. [19] Hassoun, J.; Scrosati, B. Moving to a Solid-State Configuration: a Valid Approach to Making Lithium-Sulfur Batteries Viable for Pratical Applications. Adv. Mater. 2010, 22, 5198–5201. [20] Croce, F.; Appetecchi, G.-B.; Persi, L.; Scrosati, B. Nanocomposite Polymer Electrolytes for Lithium Batteries. Nature 1998, 394, 456–458. [21] Hassoun, J.; Scrosati, B. A High-Performance Polymer Tin Sulfur Lithium Ion Battery. Angew.

Chem. Int. Ed. 2010, 49, 2371–2374. [22] Nagao, M.; Hayashi, A.; Tatsumisago, M. Fabrication of Favorable Interface between Sulfide Solid Electrolyte and Li Metal Electrode for bulk-type solid-state Li/S battery. Electrochem.

Commun. 2012, 22, 177–180.



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

[23] Wachtler, M.; Winter, M.; Besenhard, J.-O. Anodic Materials for Rechargeable Li-batteries. J.

Power Sources 2002, 105, 151–160. [24] Derrien, G.; Hassoun, J.; Panero, S.; Scrosati, B. Nanostructured Sn-C Composite as an Advanced Anode Material in High Performance Lithium-Ion Batteries Adv. Mater. 2007, 19, 2336– 2340. [25] Hassoun, J.; Derrien, G.; Panero, S.; Scrosati, B. A Nanostructured Sn-C Composite Lithium Battery Electrode with Unique Stability and High Electrochemical Performance. Adv. Mater. 2008,

20, 3169–3175. [26] Wilson, A.; Way, B.; Dahn, J.; Van Buuren, T. Nanodispersed Silicon in Pregraphitic Carbons.

J. Appl. Phys. 1995, 77, 2363–2369. [27] Bourderau, S.; Brousse, T.; Schleich, D.-M. Amorphous Silicon as a Possible Anode Material for Li-Ion Batteries. J. Power Sources 1999, 81-82, 233–236. [28] Weydanz, W.-J.; Wohlfahrt-Mehrens, M.; Huggins, R.-A. A Room Temperature Study of the Binary Lithium-Silicon and the Ternary Lithium-Chromium-Silicon System for use in Rechargeable Lithium Batteries. J. Power Sources 1999, 81-82, 237–242. [29] Besenhard, J.-O.; Yang, J.; Winter, M. Will Advanced Lithium-Alloy Anodes have a chance in Lithium-Ion batteries? J. Power Sources 1997, 68, 87–90. [30] Limthongkul, P.; Jang, Y.-I.; Dudney, N.-J.; Chiang, Y.-M. Electrochemically-driven SolidState Amorphization in Lithium-Silicon Alloys and Implications for Lithium Storage. Acta Mater.

2003, 51, 1103–1113. [31] Wu, H.; Chan, G.; Choi, J.W.; Ryu, I.; Yao, Y.; McDowell, M.T.; Lee, S.W.; Jackson, A.; Yang, Y.; Hu, L.; Cui, Y. Stable Cycling of Double-Walled Silicon Nanotube Battery Anodes through Solid-Electrolyte Interphase Control. Nat. Nanotechnol. 2012, 7, 310–315. ACS Paragon Plus Environment

Page 18 of 22

Page 19 of 22

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


[32] Nara, H.; Yokoshima, T.; Momma, T.; Osaka, T. Highly durable SiOC Composite Anode prepared by Electrodeposition for Lithium Secondary Batteries. Energy Environ. Sci. 2012, 5, 6500–6505. [33] Winter, M.; Besenhard, J.O.; Spahr, M.E; Novak, P. Insertion Electrode Materials for Rechargeable Lithium Batteries. Adv. Mater. 1998, 10, 725–763. [34] Sato, K.; Noguchi, M.; Demachi, A.; Oki, N.; Endo, M. A Mechanism of Lithium Storage in Disordered Carbons. Science 1994, 264, 556–558. [35] Dahn, J.R.; Zheng, T.; Liu, Y.; Xue, J.S. Mechanisms for Lithium Insertion in Carbonaceous Materials. Science 1995, 270, 590−593. [36] Yoo, E.; Kim, J.; Hosono, E.; Zhou, H.-S.; Kudo, T.; Honma, I. Large Reversible Li Storage of Graphene Nanosheet Families for Use in Rechargeable Lithium Ion Batteries. Nano Lett. 2008, 8, 2277–2282. [37] Guo, P.; Song, H.; Chen, X. Electrochemical Performance of Graphene Nanosheets as Anode Material for Lithium-Ion Batteries. Electrochem. Commun. 2009, 11, 1320–1324. [38] Lian, P.; Zhu, X.; Liang, S.; Li, Z.; Yang, W.; Wang, H. Large Reversible Capacity of High Quality Graphene Sheets as an Anode Material for Lithium-Ion Batteries. Electrochim. Acta 2010,

55, 3909–3914. [39] Agostini, M.; Rizzi, L.-G.; Cesareo, G.; Russo, V.; Hassoun, J. Characteristics of a Graphene Nanoplatelet Anode in Advanced Lithium-Ion Battery using Ionic Liquid Added by a Carbonate Electrolyte. Adv. Mater. Inter., 2015, 2, DOI:10.1002/admi.201570041. [40] Sun, H.; Del Rio Castillo, A. E.; Monaco, S.; Capasso, A.; Ansaldo, A.; Prato, M.; Dinh, D. A.; Pellegrini, V.; Scrosati, B.; Manna, L.; Bonaccorso, F. Binder-Free Graphene as an Advanced Anode for Lithium Batteries. J. Mater. Chem. A, 2016, DOI: 10.1039/C5TA08553E .



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

[41] Hassoun, J.; Bonaccorso, F.; Agostini, M.; Angelucci, M.; Betti, M.G.; Cingolani, R.; Gemmi, M.; Mariani, C.; Panero, S.; Pellegrini, V.; Scrosati, B. An Advanced Lithium-Ion Battery based on a Graphene Anode and a Lithium Iron Phosphate Cathode. Nano Lett. 2014, 14, 4901–4906. [42] Uthaisar, C.; Barone, V. Edge Effects on the Characteristics of Li Diffusion in Graphene. Nano

Lett. 2010, 10, 2838–2842. [43] Khan, U.; O’Neill, A.; Lotya, M.; De, S.; Coleman, N. High-Concentration Solvent Exfoliation of Graphene. Small 2010, 6, 864–871. [44] Ciesielski, A.; Samorì, P. Graphene via Sonication Assisted Liquid-Phase Exfoliation. Chem.

Soc. Rev. 2014, 43, 381–398. [45] Reale, P.; Panero, S.; Scrosati, B. Sustainable High-Voltage Lithium Ion Polymer Batteries. J.

Electrochem. Soc. 2005, 152, A1949–A1954. [46] Hernandez, Y.; Nicolosi, V.; Lotya, M.; Blighe, F.M.; Sun, Z.; De, S.; McGovern, I.T.; Holland, B.; Byrne, M.; Gun'Ko, Y.K.; Boland, J.J.; Niraj, P.; Duesberg, G.; Krishnamurthy, S.; Goodhue, R.; Hutchison, J.; Scardaci, V.; Ferrari, A.C.; Coleman, J.N. High-yield Production of Graphene by Liquid-Phase exfoliation of graphite. Nat. Nanotech. 2008, 3, 563–568. [47] Torrisi, F.; Hasan, T.; Wu, W.; Sun, Z.; Lombardo, A.; Kulmala, T. S.; Hsieh, G.-W.; Jung, S.; Bonaccorso, F.; Paul, P.J.; Chu, D.; Ferrari, A.C. Inkjet-Printed Graphene Electronics. ACS Nano

2012, 6, 2992–3006. [48] American Society for Testing Materials, Philadelphia, PA, Crystallographic Data, Card 12-21. [49] Ferrari, A.C. Raman Spectroscopy of Graphene and Graphite: Disorder, Electron-Phonon Coupling, Doping and Nonadiabatic Effects. Solid State Commun. 2007, 143, 47–57. [50] Bonino, F.; Brutti, S.; Reale, P.; Scrosati, B.; Gherghel, L.; Wu, J. A Disordered Carbon as a Novel Anode Material in Lithium-Ion Cells. Adv. Mater. 2005, 17, 743–746. ACS Paragon Plus Environment

Page 20 of 22

Page 21 of 22

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


[51] Hu, Y.S.; Adelhelm, P.; Smarsly, B.M.; Hore, S.; Antonietti, M.; Maier, J. Synthesis of Hierarchically Porous Carbon Monoliths with Highly Ordered Microstructure and their Application in Rechargeable Lithium Batteries with High-Rate Capability. Adv. Funct. Mater. 2007, 17, 1873– 1878. [52] Fong, R.; von Sacken, U; Dahn, J.R. Studies of Lithium Intercalation into Carbons Using Nonaqueous Electrochemical Cells. J. Electrochem. Soc. 1990, 137, 2009–2013. [53] Kim, J.-H.; Myung, S.-T.; Yoon, C.S.; Kang, S.G.; Sun, Y.-K. Comparative Study of LiNi0.5Mn1.5O4-δ and LiNi0.5Mn1.5O4 Cathodes Having Two Crystallographic Structures: Fd3̄m and P4332. Chem. Mater. 2004, 16, 906–914. [54]

Xia, Y.; Sakai, T.; Fujieda, T.; Wada, M.; Yoshinaga, H. A 4 V Lithium-Ion Battery Based

on a 5 V LiNixMn2−xO4 Cathode and a Flake Cu-Sn Microcomposite Anode. Electrochem. Solid

State Lett. 2001, 4, A9-A11. [55] Ariyoshi, K.; Yamamoto, S.; Ohzuku, T.

Three-Volt Lithium-Ion Battery with

Li[Ni1/2Mn3/2]O4 and the Zero-Strain Insertion Material of Li[Li1/3Ti5/3]O4. J. Power Sources, 2003,

119–121, 959–963. [56] Arrebola, J. C.; Caballero, A.; Hernán, L.; Morales, J. A High Energy Li-Ion Battery Based on Nanosized LiNi0.5Mn1.5O4 cathode material. J. Power Sources, 2008, 183, 310–315. [57] Arrebola, J.C.; Caballero, A.; Gómez-Cámer, J.L.; Hernán, L.; Morales, J.; Sánchez, L. Combining 5 V LiNi0.5Mn1.5O4 Spinel and Si Nanoparticles for Advanced Li-Ion Batteries.

Electrochem. Commun. 2009, 11, 1061–1064.



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