Effect of the Lithiation Protocol - ACS Publications - American

Article pubs.acs.org/JPCC

Cycling Behavior of Silicon-Containing Graphite Electrodes, Part A: Effect of the Lithiation Protocol Tiphaine Schott,† Rosa Robert,† Pirmin A. Ulmann,‡ Patrick Lanz,‡ Simone Zürcher,‡ Michael E. Spahr,‡ Petr Novák,† and Sigita Trabesinger*,† †

Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Imerys Graphite & Carbon, CH-6743 Bodio, Switzerland

‡

S Supporting Information *

ABSTRACT: Silicon (Si) is a promising additive for enhancing the specific charge of graphite negative electrodes in Li-ion batteries. However, Si alloying with lithium leads to an extreme volume expansion and in turn to rapid performance decline. Here we present how controlling the lithiation depth affects the performance of graphite/Si electrodes when different lithiation cutoff potentials are applied. The relationship between Si particle size and cutoff potential was investigated to clarify the interdependence of these two parameters and their impact on the performance of Sicontaining graphite electrodes. For Si with a particle size of 30−50 nm, Li15Si4 is only formed for the potential cutoff of 5 mV vs Li+/Li, whereas using a higher cutoff of 50 mV has no impact on the performance. For larger Si nanoparticles, 70−130 nm in size, Li15Si4 is already formed at 50 mV. However, in these larger particles only 70% of the Si initially participates in the lithiation, independent of the cutoff potential (5 or 50 mV), and the performance fades rapidly. For the highest tested cutoff potential of 120 mV, the contribution of larger Si particles to the specific charge of the electrodes was negligible, but for the smaller particles a stable and still significant Si specific charge was obtained.

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INTRODUCTION In the quest for Li-ion batteries with high energy densities, graphite is not sufficient anymore as a sole negative-electrode material given that its theoretical limits for specific charge have already been reached, even in commercial cells. Therefore, a solution has to be sought to enhance the specific charge of graphite. Silicon (Si) as an electrode additive is a promising candidate, due to its high theoretical specific charge, which is ∼10 times higher than that of graphite. Although Si has recently attracted much attention as a material for negative electrodes,1−3 the commercialization of Si-based electrodes is hindered by their poor cycling stability compared to graphite. In particular, the alloying of Si with Li induces a significant expansion of Si particles (∼300% volume increase), which gradually destroys the mechanical integrity of the electrode and leads to Si being disconnected from the conductive network of the electrode. Recent research has been focused on obtaining a fuller understanding of the cycling mechanism of Si4 to optimize the performance of Si-containing graphite electrodes. The groups of Obrovac and Dahn have demonstrated using ex situ5 and in situ6,7 X-ray-diffraction (XRD) that a crystalline Li−Si alloy, Li15Si4, is formed at deep silicon lithiation and that the presence of this phase leads to a characteristic delithiation potential plateau at ∼0.45 V vs Li+/Li.5,8 As the kinetics of Li15Si4 formation is slow, the formation of this crystalline phase is affected by both the cycling rate (applied current) and the applied cutoff potential. When the lithiation cutoff potential is © 2017 American Chemical Society

set too high, an insufficient number of lithium ions are inserted into Si, preventing the formation of the Li15Si4 alloy. This is why the corresponding potential plateau is not observed during the following delithiation when high cutoff potentials are used for lithiation.5,8 The cycling rate also affects the formation of this crystalline phase as even for sufficiently low cutoff potentials faster cycling leads to higher overpotentials, thus making the formation of Li15Si4 impossible in the studied potential window. Consequently, the delithiation plateau is also absent at fast lithiation rates,9,10 and no crystalline phase could be detected by in situ XRD in silicon nanowires for potentials as low as 0 V vs Li+/Li for rates higher than C/2.11 As the formation of the highly lithiated phase is responsible for the extreme volume changes, the cycling and failure mechanism of every Si-containing composite is strongly dependent on the applied cycling protocol. These considerations motivated us to clarify the effect of the lithiation cutoff potential conditions on the electrochemical performance of commercially viable graphite/Si composite electrodes in order to find the optimal cycling protocol for long cycle life while achieving reasonable specific charge at the electrode level. Received: June 16, 2017 Revised: August 5, 2017 Published: August 8, 2017 18423

DOI: 10.1021/acs.jpcc.7b05919 J. Phys. Chem. C 2017, 121, 18423−18429

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The Journal of Physical Chemistry C

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EXPERIMENTAL METHODS Electrode Preparation. A binder mixture of carboxymethyl cellulose (CMC, Alfa Aesar) and poly(acrylic acid) (PAA, 25 wt % solution in water, MW 240,000, Alfa Aesar) (1:1) was prepared in a water/ethanol (70:30) solution. This binder combination and solvent mixture were chosen as they were reported to lead to good cycling performance for siliconcontaining electrodes.12−14 Two types of silicon nanoparticles were used in this work: (i) 30−50 nm (98%, Nanostructured & Amorphous Materials), further referred to as Si 30−50, and (ii) 70−130 nm (>99%, Nanostructured & Amorphous Materials), further referred to as Si 70−130. The silicon nanoparticles, the carbon additive C-NERGY SuperC45 (SBET = 45 m2 g−1, IMERYS Graphite & Carbon), and graphite powder C-NERGY KS6L (SBET = 20 m2 g−1, IMERYS Graphite & Carbon) were homogenized using a turbo stirrer (IKA Ultra-Turrax T25 basic) with the CMC/PAA binder (predissolved in the water/ ethanol mixture) to obtain an electrode composition of 5 wt % Si, 90 wt % graphite, 1 wt % carbon additive, and 4 wt % binder. For comparison, silicon-free electrodes (95 wt % graphite, 1 wt % carbon additive, 4 wt % binder) and electrodes containing 10 wt % silicon (10 wt % Si, 85 wt % graphite, 1 wt % carbon additive, 4 wt % binder) were also evaluated, keeping the activematerial (graphite and silicon) content constant at 95 wt %. After degassing the prepared slurries for 2 h on a roller mixer, they were cast onto copper foil using the doctor-blade technique. The cast electrode sheets were then heat treated at 150 °C under vacuum for 2 h in order to initiate the crosslinking reaction between CMC and PAA12 and then further dried under vacuum at 80 °C for ∼12 h to remove any residual water. Circular electrodes of 13 mm diameter were punched out with a coating mass of ∼8 mg cm−2. Electrochemical Characterization. The electrodes were dried for ∼12 h at 120 °C under vacuum and assembled in an argon-filled glovebox into coin-type cells with metallic lithium (≥99.9%, thickness 0.75 mm, Alfa Aesar) as the counter electrode and 1 mL of 1 M LiPF6 in ethylene carbonate (EC)/ dimethyl carbonate (DMC) (1:1) with 2 wt % FEC (BASF) as the electrolyte. FEC additive was chosen as it is well known to improve the solid−electrolyte interphase (SEI) of silicon-based electrodes, although we found that thick separators are still required to delay half-cell short circuits from FEC-induced lithium-dendrite growth.15 Thus, three glass-fiber separators (total uncompressed thickness ≈ 3 mm) were used. The electrochemical measurements were carried out with a standard battery cycler (Astrol Electronics AG, Switzerland) at 25 °C, and several cycling protocols were investigated by varying the lithiation cutoff potential and constant voltage (CV) step, as indicated in Table 1. The following cycling procedure was applied: the first constant-current (CC) cycle was performed at a slow rate (20 mA g−1) to allow the formation of the SEI, whereas further CC cycles were performed at 50 mA g−1 for the lithiation and at 186 mA g−1

for the delithiation. After each CC delithiation step and for some cells (as indicated in Table 1) also after each CC lithiation step the cutoff potential (5, 50, or 120 mV for lithiation, 1.5 V for delithiation) was maintained until the current dropped below 5 mA g−1 (CV step). Fifty cycles were achieved within 3−4 weeks using this cycling protocol. In this study, the potential is given vs Li+/Li and the specific charge and cycling current are denoted per mass of the whole electrode coating. Ex Situ XRD Analysis. Phase composition and crystallinity of the pristine and cycled electrodes were determined ex situ by XRD at room temperature using a PANalytical Empyrean diffractometer equipped with a linear detector (X′Celerator). Cycled electrodes were first rinsed with DMC to remove the residues of salt and electrolyte from the surface of the electrodes. After that the electrode films were removed from the copper current collector and placed in a 0.5 mm diameter capillary. Diffraction patterns were recorded using Cu Kα radiation over the 2θ range of 15° ≤ 2θ ≤ 135° in transmission mode.

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RESULTS AND DISCUSSION To assess the effect of the cutoff potential on the silicon utilization, cycling with various lithiation cutoff potentials was performed with and without a CV step. The cycling performance is shown in Figure 1 for graphite electrodes containing 5 wt % Si for the two sizes of silicon nanoparticles (Si 30−50 and Si 70−130). The results obtained for graphite without silicon can be found in the Supporting Information (Figure S1) for comparison. For all the electrodes studied, the obtained specific charge and the cycling stability are rather similar for 5 mV CCCV (Figure 1, red full symbols), 5 mV CC (Figure 1, red empty symbols), and 50 mV CCCV (Figure 1, blue full symbols) cycling conditions. However, when the 50 mV CC cycling protocol (Figure 1, blue empty symbols) is used, the obtained practical specific charge rapidly fades during the first cycles before reaching a stable value, lower by 160−180 mAh g−1 than that obtained with the 50 mV CCCV and 5 mV CC and CCCV protocols. This suggests that a large portion of the electrode lithiation occurs at or below 50 mV. With a cutoff potential of 120 mV (Figure 1, green symbols), the lithiation specific charge is rather stable. It even increases during the first cycles; however, it is still significantly lower than the values obtained for the other lithiation cutoff potentials tested. Slightly higher specific charge values were obtained for Si-containing electrodes with 120 mV CCCV (Figure 1, green full symbols) protocol, while no effect of the CV step is observed with Si-free electrodes (Figure S1, green full symbols). Interestingly, the contribution of the galvanostatic charge to the total one delivered by the studied electrodes (Figure 1c and 1d, Figure S1b) is always larger than that expected from the experiments without the CV step (Figure 1a and 1b, Figure S1a) for all the lithiation cutoff potentials used here. This shows that maintaining the potential at the end of the lithiation helps not only for the corresponding cycle but also for following cycles and, in turn, for long-term cycling. It is also noteworthy that independently of the electrode composition (Figure 1a and 1b, Figure S1a), the first cycle efficiency is lower (below 60%) for the 120 mV lithiation cutoff potential than for 50 or 5 mV (around 80%). This is most probably due to the fact that graphite surface groups are mainly reduced and SEI is formed at potentials positive to 120 mV; therefore, their contribution to

Table 1. Definition of Cycling Protocols cycling conditions

5 mV cutoff

50 mV cutoff

120 mV cutoffa

no CV step CV stepb

5 mV CC 5 mV CCCV

50 mV CC 50 mV CCCV

120 mV CC 120 mV CCCV

a

A 120 mV cutoff potential was reported to lead to stable cycling of Sibased electrodes.14 bPotential maintained until the current drops below 5 mA g−1. 18424


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Figure 1. (a, b) Cycling performance (specific charge, squares; Coulombic efficiency, stars) and (c, d) contribution of the galvanostatic charge (filled area) to the total specific charge (square symbols) of graphite electrodes with 5 wt % of (a, c) Si 30−50 and (b, d) Si 70−130 using various cycling protocols.

Figure 2. Voltage profiles of graphite electrodes with 5 wt % Si 30−50 for (a) 5, (b) 50, and (c) 120 mV CCCV and (d) 5, (e) 50, and (f) 120 mV CC cycling protocols.

potential and by the presence of a CV step. Moreover, electrodes containing larger particles, Si 70−130, exhibit significantly worse cycling performance (Figure 1b) than electrodes with Si 30−50 (Figure 1a). This is contrary to previous studies reporting a similar or enhanced performance using larger commercial nanoparticles.16,17 Indeed, in our case the following observations hold for all cycling conditions: (i) the practical specific charge of electrodes containing Si 70−130 is much lower right from the first cycle, as also found previously

irreversible charge loss relative to the attained reversible charge is much higher. No further effect of the cycling conditions on the Coulombic efficiency, which is close to 100% after the first cycle, was observed. This means in particular that no excessive growth of SEI on the freshly exposed Si surface (from possible particle cracking) occurs during cycling under any of the tested cycling conditions. All of these results clearly demonstrate that the cycling behavior of the electrodes studied is affected both by the cutoff 18425


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Figure 3. Voltage profiles of graphite electrodes with 5 wt % Si 70−130 for (a) 5, (b) 50, and (c) 120 mV CCCV and (d) 5, (e) 50, and (f) 120 mV CC cycling protocols.

Figure 4. (a, b) Differential capacity plots of the first cycle and (c, d) normalized ex situ XRD patterns after the first lithiation of graphite electrodes with 5 wt % (a, c) Si 30−50 and (b, d) Si 70−130 using 5 or 50 mV CCCV cycling protocols.

for 100 nm sized compared to 50 nm sized silicon,9 (ii) the fading upon cycling is much stronger for larger particles (Si 70−130), and (iii) the Coulombic efficiency of the first cycle is slightly higher for the smaller silicon nanoparticles (Si 30−50), although the accessible surface area for electrolyte reduction (and thus the irreversible “loss” of specific charge) was expected to be higher for the smaller particles. Differences in the voltage profiles and their dependence on the cycling protocol are also clear for the two types of Si nanoparticles (Figures 2 and 3). First, for electrodes with either type of Si the first cycle is characterized by extra specific charge

above 0.3 V, due to electrolyte decomposition and subsequent SEI formation. Then the voltage profiles are dominated by graphite lithiation/delithiation features (see also Figure S2), with the silicon lithiation/delithiation processes being only represented, if at all, by a plateau corresponding to the delithiation of the crystalline Li15Si4 alloy at ∼0.44 V and a slope due to the lithiation of amorphous silicon at ∼0.25 V.5 Furthermore, for all electrode compositions the potentials of the delithiation processes are lower during the first cycle than during the following cycles. This is due to the cycling rate, 18426


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The Journal of Physical Chemistry C which was significantly lower for the first cycle, leading to lower delithiation overpotentials. For electrodes containing Si 30−50, the plateau of Li15Si4 delithiation is only present for the 5 mV CCCV cycling protocol (Figure 2a). Interestingly, it seems that here the crystalline phase is only formed at very deep lithiation, that is, it is not formed when the 50 mV CC and 50 mV CCCV cycling protocols are applied (Figure 2b) or for the 5 mV CC protocol without a CV step (Figure 2d). This, however, does not have a significant effect on the cycling behavior, as only a minor loss of specific charge is observed. Surprisingly, no improvement in the cycling stability is seen when Li15Si4 is not formed, contrary to some literature reports.10,11,18 Most probably, the presence of Li15Si4 only affects the cycling stability either when the volume changes are not well managed in the electrode (for instance, due to a higher silicon content and usage of suboptimal binders) or for poorer interface management (such as cycling without FEC additive). With the 50 mV CC cycling protocol (Figure 2e), the specific charge of electrodes containing Si 30−50 rapidly fades because the lithiation is stopped on a plateau, where a tiny change in the overpotential leads to substantial changes in the lithiation depth. With a cutoff potential of 120 mV, both for CC and for CCCV cycling protocols, the lithiation depth is clearly insufficient to recover specific charge for the following cycles (Figure 2c and 2f). This is also the case for Si 70−130 under the same cycling conditions (Figure 3c and 3f). With these larger silicon particles, the voltage profiles look different from those for Si 30−50, when 5 and 50 mV lithiation cutoff potentials are used. Indeed, the plateau attributed to the delithiation of the crystalline alloy is present for these two cutoff potentials independently of the presence of the CV step (Figure 3a, 3b, 3d, and 3e). The presence of the Li15Si4 phase can be more easily identified in the differential-capacity plots and through ex situ XRD analysis of electrodes containing either type of silicon nanoparticles (Figure 4). In the differential-capacity plots, the peaks below 0.3 V correspond to different stages of graphite lithiation and delithiation (Figure S3) and the peak at ∼0.44 V is attributed to the crystalline phase Li15Si4 on delithiation (Figure 4a and 4b), whereas the lithiation of crystalline Si and graphite to Li15Si4 and LiC6, respectively, is confirmed by the XRD patterns shown in Figure 4c and 4d. For both types of Si, using the 5 mV CCCV cycling protocol, the crystalline Li−Si alloy is detected (Figure 4). However, when the cutoff potential is increased to 50 mV, Li15Si4 is only found in electrodes with Si 70−130. For electrodes containing Si 30−50, no peak at 0.44 V is observed in the differential-capacity plot and no Li15Si4 phase is detected using XRD (Figure 4). This demonstrates that Li15Si4 is formed at more positive potentials for Si 70−130 than for Si 30−50. As for the larger silicon nanoparticles this crystalline phase is formed both with 5 and with 50 mV cutoff potentials, it is not possible to assess the impact of cutoff potentials on the cycling stability of the corresponding electrodes. Nonetheless, the corresponding delithiation plateau rapidly shortens during cycling Si 70−130 (Figure 3a, 3b, 3d, and 3e) with both the CC and CCCV protocols but especially without a CV step, leading to voltage profiles very similar to those of graphite electrodes (Figure S2) and to low specific charge (Figure 1b). For Si-free graphite electrodes, it is observed that 5 mV CCCV, 5 mV CC, or 50 mV CCCV cutoff conditions lead to identical voltage profiles (Figure S2a, S2b, S2d). However,

when the potential is not maintained longer at 50 mV (CV step is not present), the specific charge drastically decreases due to incomplete lithiation of graphite (Figure S2e). This explains the specific charge loss observed for Si-containing electrodes for these cycling conditions. With a cutoff potential of 120 mV, only the first lithiation plateau of graphite is reached, and its length is too short to result in specific charge of any significance (Figure S2f). In this case, the CV step has no effect (Figure S2c) as the lithiation potential of graphite is significantly lower, whereas it was helping to increase the specific charge for Sicontaining electrodes (Figures 2c and 3c). It shows that the loss of specific charge provided by graphite in Si-containing electrodes was compensated for by silicon under these conditions. In order to determine more precisely the effect of the cycling protocol on the individual contribution of silicon, the specific charge of the graphite electrodes (Figure S1, after correction accounting for the amount of active material) was subtracted from the one of the silicon-containing electrodes (Figure 1) for each cycling protocol. The resulting contributions are plotted in Figure 5 for both types of silicon nanoparticles and compared to the theoretical specific charge of the electrodes.

Figure 5. Contribution of graphite (black) and silicon to the total specific charge of graphite electrodes with 5 wt % (a) Si 30−50 (blue) and (b) Si 70−130 (red) for the second lithiation (darker color) and the 50th lithiation (lighter color) for various lithiation cutoff potential conditions.

On one hand, the specific charge reached by silicon alone is in fact close to the theoretical value for cutoff potentials of 5 and 50 mV with and without a CV step for Si 30−50 (Figure 5a, blue). This is valid even after 50 cycles, as the cycling stability is good for this size of silicon nanoparticles. This demonstrates that the specific charge loss observed with 50 mV CC is only due to incomplete graphite lithiation, while silicon is fully lithiated. On the other hand, when the lithiation is stopped 18427


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the electrode would suffer from the consequences of Si volume expansion, such as loss of electrical contact with Si particles and irreversible electrode volume changes. As a consequence, the calculated performance after long-term cycling may be overestimated for heavy Si loadings, and therefore, Si 70−130 is probably not viable for the development of commercial electrodes. By contrast, one can expect 600 mAh g−1 after 50 cycles with graphite electrodes containing only 8 wt % of Si 30−50 (Figure 6, blue). High cutoff potential conditions are of practical interest if the aim is to avoid lithium plating and to have stable Si specific charge. However, high cutoff potentials should not be applied to electrodes mainly composed of graphite due to the low potential of its lithiation reactions. Thus, if high lithiation cutoff potentials are to be used, the electrode matrix material should be either optimized to be active in the studied potential window or cheap enough to only serve as conductive medium as well as for buffering silicon volume changes, with the silicon content being increased to compensate for the loss of specific charge due to the absence of graphite as a second active material. However, Si is not fully utilized in such cycling conditions, and more importantly, an increase in the Si relative content leads to lower Si utilization, as illustrated by the results obtained with 5 and 10 wt % silicon using the 120 mV cutoff potential (Figure 5, Figure S7).

at 120 mV, there is almost no silicon contribution to the specific charge when the CV step is not applied. Under such cycling conditions, graphite (Figure 5, black) does not contribute much to electrode specific charge either. However, when a potential of 120 mV is maintained for a sufficiently long time, the specific charge reached by Si 30−50 is relatively high (>100 mAh g−1 after 50 cycles). For Si 70−130 (Figure 5b, red), the silicon contribution to the specific charge is lower than the theoretical value during the first cycles for all cycling conditions. These calculations show that indeed only ∼70% of Si 70−130 nanoparticles are initially utilized at 5 and 50 mV cutoff potentials conditions. The silicon contribution is even lower when a 120 mV cutoff potential limit is applied. After 50 cycles, less than 50 mAh g−1 is reached by Si 70−130, independently of the cycling conditions, indicating strong performance fading. Identical experiments and calculations were then performed for electrodes containing 10 wt % silicon, where the increased silicon amount was expected to compensate for the loss of specific charge due to incomplete lithiation of graphite at higher cutoff potentials. Similar effects of the cycling protocol were found for this higher Si content, as discussed in the Supporting Information (Figures S4−S7). In particular, for such a high cutoff potential quite high and stable specific charge values for Si 30−50 were obtained using the 120 mV CCCV protocol. However, the best electrode cycling performance was still achieved with 5 mV CC, 5 mV CCCV, and 50 mV CCCV cycling conditions for electrodes containing either type of silicon nanoparticles with this higher Si content. To estimate the specific charge of the electrode for various lithiation cutoff conditions, it was calculated assuming the Si relative content in the electrode to be 0 ≤ x ≤ 100 [%] by extrapolation of known specific charge values for electrodes with 0, 5, and 10 wt % silicon for cycles 2 and 50 (Figure 6).

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CONCLUSIONS We have demonstrated that the utilization, the lithiation depth, and the cycling stability of graphite/Si electrodes are dependent on both the cycling protocol and the Si particle size. For Si with a particle size of 30−50 nm, we found that the crystalline Li15Si4 alloy is only formed upon deep lithiation, when the potential is maintained at 5 mV for a given time. Nevertheless, stopping the lithiation at higher potentials to avoid the formation of this alloy with large volume changes has no impact on the performance stability, which was satisfactory for all the studied cycling conditions with this Si particle size. Moreover, the contribution of silicon to the electrode specific charge is close to the theoretical value for cutoff potentials of 50 mV and below, suggesting good utilization of these small Si particles under such cycling conditions. However, lower cutoff potentials or a CV step at 50 mV are required to get the full specific charge of graphite. When lithiation cutoff potentials as high as 120 mV are used, the contribution of graphite to the electrode specific charge is too insignificant to be used for electrodes with graphite as a conductive matrix. Nonetheless, a stable and reasonable (∼60% of the theoretical value using 5% Si) Si specific charge can be reached when the cell is kept longer at 120 mV, but its contribution is not proportional to the relative amount of Si. For the second type of Si tested, with a particle size of 70− 130 nm, Li15Si4 was formed already at 50 mV. However, at most only ∼70% of Si contributes to the electrode specific charge in the first cycle, whereas the Si contribution is negligible when the cutoff potential is increased to 120 mV. Moreover, crystalline Si features present in the voltage profiles using cutoff potentials equal or below 50 mV rapidly disappear, leading to strong performance fading during the following cycles. Therefore, significantly higher amounts of this type of Si are required to reach a similar electrode specific charge than for Si with a particle size of 30−50 nm for all cycling conditions. However, higher Si relative amounts would make the electrical

Figure 6. Specific charge per electrode mass expected for Si−graphite electrodes with various relative amounts of Si 30−50 (blue) and Si 70−130 (red) for the best cycling conditions (5 mV CC, 5 mV CCCV, and 50 mV CCCV). Linear extrapolation from experimental data with low Si content (not accounting for the negative effects due to high Si and low conductive additive content).

From this extrapolation, higher practical specific charge values are expected for Si 30−50, that is, 7 wt % of Si 30−50 is required to initially reach 600 mAh g−1, whereas Si 70−130 requires larger amounts of silicon (12 wt %) to reach similar specific charge per electrode mass. Moreover, performance fading with Si 70−130 is very large; thus, at least 47 wt % of Si 70−130 would be required in graphite electrodes to stay above the specific charge of 600 mAh g−1 during long-term cycling (Figure 6, red). However, with such large amounts of silicon, 18428


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contact worse, amplify volume changes, and therefore lead to even worse cycling performance.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpcc.7b05919. Cycling performance of silicon-free electrodes; cycling performance of electrodes containing 10 wt % silicon (PDF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Phone: +41563105775. ORCID

Sigita Trabesinger: 0000-0001-5878-300X Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS IMERYS Graphite & Carbon is gratefully acknowledged for financial support. REFERENCES

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