New insights into the silicon-based electrode's irreversibility along cycle life through simple gravimetric method

Mazouzi, Driss; Delpuech, Nathalie; Oumellal, Yassine; Gauthier, Magali; Cerbelaud, Manuella; Gaubicher, Joël; Dupré, Nicolas; Moreau, Philippe; Guyomard, Dominique; Roué, Lionel; Lestriez, Bernard

doi:10.1016/j.jpowsour.2012.08.007

Cited by 96 publications

(133 citation statements)

References 30 publications

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“…However, as our results from galvanostatic cycling clearly prove a residual reversible capacity of ∼70% after 120 cycles for the 60 wt% silicon electrode (see Figure 2), we conclude that the electrodes must significantly swell upon cycling in order to increase the available pore volume and thus facilitate the accommodation of the FEC decomposition products while simultaneously conserving the ionic conduction pathways. These conclusions agree well with the thickness measurements and cross-sectional SEM images of cycled silicon electrodes reported by Mazouzi et al 53 Obrovac and co-workers measured the coating thickness of Sialloy/graphite composite electrodes in their fully lithiated state and found that the entire coating expanded by about ∼96%, which was very similar to the expected expansion of the lithiated Si-alloy (∼115%). 15 Interestingly, the porosity of these electrodes remained nearly the same as in the delithiated state, leading them to the conclusion that the pore size expands by the same amount as the silicon particles.…”

Section: −1supporting

confidence: 91%

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Wetjen

Pritzl

Jung

et al. 2017

J. Electrochem. Soc.

145

173

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Silicon-graphite electrodes usually experience an increase in cycling performance by the addition of graphite, however, the relation of the silicon/graphite ratio and the aging mechanisms of the individual electrode and electrolyte compounds still requires a more fundamental understanding. In this study, we present a comprehensive approach to understand and quantify the degradation phenomena in silicon-graphite electrodes with silicon contents between 20-60 wt%. By evaluating the cycling performance and total irreversible capacity of silicon-graphite electrodes vs. capacitively oversized LiFePO 4 electrodes in presence of a fluoroethylene carbonate (FEC)-containing electrolyte, we demonstrate that the aging of silicon-based electrodes can be distinguished into two distinct phenomena, which we describe as silicon particle degradation and electrode degradation. Cross-sectional scanning electron microscopy (SEM) images and a detailed analysis of the electrode polarization upon cycling complement our discussion. Further, we deploy post-mortem 19 F-NMR spectroscopy to (i) quantify to loss of moles of FEC in the electrolyte and correlate this with the amount of charge that was exchanged by the silicon-graphite electrodes, (ii) estimate the pore volume of the silicon-graphite electrodes that is occupied by FEC decomposition products, and (iii) Silicon-based electrodes are very promising candidates to enable the next generation of Li-ion batteries with energy densities on the cell level beyond 350 Wh kg −1 . 1,2 In contrast to conventional intercalation anode materials, such as graphite (LiC 6 , 372 mAh g −1 , 890 Ah L −1 ), the specific capacity of silicon alloy electrodes is significantly higher (Li 15 Si 4 , 3579 mAh g −1 , 2194 Ah L −1 ). 3 Nonetheless, commercialization of silicon-based electrodes is still hampered because of two major challenges: 4 (i) Large volume expansions up to 280% upon repeated (de-)lithiation of silicon particles deteriorate the electrode integrity, thus causing isolation of active material. [5][6][7] The formerly reported pulverization of micron-sized silicon particles due to mechanical stress upon repeated volume expansion has been partially solved by using nanometer-sized particles. However, reduction of the silicon particle size also leads to inferior electronic conduction due to more numerous interparticle contacts, and higher solid-electrolyte-interphase (SEI) losses due to the larger relative surface area. [8][9][10] (ii) Continuous side reactions at the silicon/electrolyte interface caused by repeated volume expansion and contraction result in ongoing electrolyte decomposition and in a gradual loss of active lithium. 8In the course of this, SEI-forming additives in the electrolyte, e.g., FEC, are depleted, which was shown to result in a significant increase in cell polarization and a concomitant rapid capacity drop. 8,11 Various strategies have been proposed to overcome the detrimental effects associated with the volume expansion during (de-)lithiation of silicon and to reduce conc...

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Section: −1supporting

confidence: 91%

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Wetjen

Pritzl

Jung

et al. 2017

J. Electrochem. Soc.

145

173

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“…In an interesting study, Mazouzi et al measured the thickness and weight of cycled n-Si electrodes after cycling. 380 They found that both the electrode thickness and the weight are highly correlated to the capacity loss. The thickness, weight gain, and capacity loss could be greatly reduced when FEC and VC additives were present in the electrolyte, in conjunction with a good performance binder.…”

Section: Electrolytes and Additivesmentioning

confidence: 99%

Alloy Negative Electrodes for Li-Ion Batteries

2014

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“…3 This irreversibility is much higher during the first cycle (CE = 79%) due to the buildup of the SEI layer onto fresh Si particles, which then tends to reach a steady state after several cycles (CE stabilizes around 96% from the 30 th cycle) as the SEI layer grows at a constant rate. 36 The progressive decrease of the end-of-discharge potential with cycling ( Fig. 7b) reflects the rise in the polarization resistance of the electrode due the accumulation of SEI products on the Si particles, which inhibits lithium diffusion through the composite electrode.…”

mentioning

confidence: 99%

“…This agrees well with thickness measurements obtained from ex-situ SEM observations on nano Si/C/CMC electrodes cycled at 1200 mAh g −1 . 36 This irreversible swelling of the electrode is attributed to the progressive accumulation of insoluble solvent degradation products. Note that during the first 2 cycles, a slight irreversible contraction (up to 5%) of the electrode is observed, which may reflect some rearrangements of the initial composite electrode architecture due to the motion and shape/size variation of the Si particles during their lithiation / delithiation.…”

mentioning

confidence: 99%

Impact of the Slurry pH on the Expansion/Contraction Behavior of Silicon/Carbon/Carboxymethylcellulose Electrodes for Li-Ion Batteries

Tranchot

Idrissi

Thivel

et al. 2016

J. Electrochem. Soc.

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Electrochemical dilatometry experiments were performed on silicon/carbon/carboxymethylcellulose (Si/C/CMC) composite electrodes prepared with pH7 and buffered pH3 slurries. It was shown that the pH3 electrode better accommodates the severe volume change of the micrometric Si particles, inducing a much better capacity retention with cycling (70% after 10 cycles compared to only 6% for the pH7 electrode). During the first discharge (lithiation), a maximum electrode thickness expansion of ∼170% was observed for the pH3 electrode compared to ∼330% for the pH7 electrode. A lower irreversible expansion was also observed at the end of the 1 st cycle (∼50% compared to ∼180% for the pH7 electrode). It was explained by the fact that the pH3 of the slurry, which is known to favor the formation covalent bonds between the Si particles and the CMC chains, greatly improves the cohesive strength of the electrode as supported by the higher hardness and elastic modulus of the pH3 electrode. When the discharge capacity was limited to 1200 mAh g −1 , a progressive and irreversible swelling of the pH3 electrode was observed upon prolonged cycling, which was attributed to the accumulation of solid electrolyte interface (SEI) products. Silicon is a very attractive active material for Li-ion battery anodes due to its ∼10 times higher gravimetric capacity and ∼3 times higher volumetric capacity than conventional graphite anode (i.e., 3579 mAh g −1 and 2190 mAh cm −3 for Li 15 Si 4 compared to 372 mAh g −1 and 719 mAh cm −3 for LiC 6 ). However, obtaining commercially viable Sibased anodes is very challenging due to the large volume expansion of Si during its lithiation (∼280% from Si to Li 15 Si 4 ).1 This leads to the fracture and rearrangement of the Si particles, inducing the rupture of the electrical network in the composite electrode. As a result, a rapid capacity decay with cycling is observed.2 The large Si volume change also induces an instability of the solid electrolyte interface (SEI), which continuously grows with cycling, decreasing the coulombic efficiency (CE) and increasing the electrode impedance.3 To address these issues, numerous strategies have been investigated for several years as reviewed in Refs. 4-8 with a few significant successes in the improvement of the cycle life of Si-based electrodes (>1000 cycles, at least in half-cell).9-15 Actually, further work is still required to tackle the issue of SEI stability and to obtain low-cost Si-based electrodes with practical relevant surface, gravimetric and volumetric capacities.Considering that the volume change of Si-based electrodes largely contributes to their degradation, monitoring their expansion and contraction with cycling is highly relevant to evaluate the impact of the composite electrode formulation and morphology, and cycling conditions on this process. For this purpose, a simple and efficient method consists of integrating a non-contact gap sensor 16 or a contact displacement transducer 17 to the electrochemical cell, which permits a measurement of any ver...

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New insights into the silicon-based electrode's irreversibility along cycle life through simple gravimetric method

Cited by 96 publications

References 30 publications

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Differentiating the Degradation Phenomena in Silicon-Graphite Electrodes for Lithium-Ion Batteries

Alloy Negative Electrodes for Li-Ion Batteries

Impact of the Slurry pH on the Expansion/Contraction Behavior of Silicon/Carbon/Carboxymethylcellulose Electrodes for Li-Ion Batteries

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