Parasitic Reactions in Nanosized Silicon Anodes for Lithium-Ion Batteries

Abstract

When designing nano-Si electrodes for lithium-ion batteries, the detrimental effect of the c-LiSi phase formed upon full lithiation is often a concern. In this study, Si nanoparticles with controlled particle sizes and morphology were synthesized, and parasitic reactions of the metastable c-LiSi phase with the nonaqueous electrolyte was investigated. The use of smaller Si nanoparticles (∼60 nm) and the addition of fluoroethylene carbonate additive played decisive roles in the parasitic reactions such that the c-LiSi phase could disappear at the end of lithiation. This suppression of c-LiSi improved the cycle life of the nano-Si electrodes but with a little loss of specific capacity. In addition, the characteristic c-LiSi peak in the differential capacity (dQ/dV) plots can be used as an early-stage indicator of cell capacity fade during cycling. Our findings can contribute to the design guidelines of Si electrodes and allow us to quantify another factor to the performance of the Si electrodes.

The Electrochemical Performance of Silicon Nanoparticles in Concentrated Electrolyte

“…The electrochemicalp erformance of 1.0 m LiPF 6 -EC/DEC/DMC (ethylene carbonate/diethyl carbonate/dimethyl carbonate) is similar to LiFSI-(PC) 8 .T he SiNP electrodes in LiFSI-(PC) 3 and LiFSI-(PC) 2 show remarkable improved capacity retention of 42.7 %a nd 63.5 %, exhibiting delithiation capacities of 1425.1 and 1997.9 mAh g À1 ,r espectively.I nd etail, the CE of the SiNP electrode with LiFSI-(PC) 8 begins to fade after 6-8 cycles,d ecreases sharply at about the 15th cycle, and then recovers beyond 20 cycles,c orresponding to an initial rising stage, hump stage, [14] and stabilization stage (Figure 2a nd Ta ble S1 in the Supporting Information). [16] However,i td oes not seem to be the case here as the dQ/dV peaks for all three electrolytes have peaks at similar potentials. In LiFSI-(PC) 3 ,t he CE of the SiNP electrode also experiences three stages as discussed above,b ut the hump stage appears at around the 20th cycle and the hump is not as intense as the dilute electrolyte.…”

“…The initial CE of LiFSI-(PC) 2 is slightly lower than that of LiFSI-(PC) 8 ,w hich originates from the difference of the electrolyte decomposition reactions on the surface of SiNPs.A tt he 100th cycle, the delithiationc apacity of the SiNP electrode in LiFSI-(PC) 8 is 257.4 mAh g À1 with capacity retention of 7.5 %. [16] However, in the two concentrated electrolytes, no clear sign of c-Li 3.75 Si formation appears. The capacity of the electrode decreasess harply during the first 50 cycles,a nd the capacity retention at the 50th cycle is only 19.9 %.…”

Solid‐State Lithium/Selenium–Sulfur Chemistry Enabled via a Robust Solid‐Electrolyte Interphase

“…Note that although hydrofluoroether electrolyte has been previously reported for S cathodes by others, [39,40] Adv. [41][42][43][44] The cells were discharged/charged for two cycles and then charged to a different potential and held for 20 h to obtain the equilibrium current. 2019, 9,1802235 their main focus is the suppressed polysulfides dissolution and enhanced solvation capability.…”

Boosting Superior Lithium Storage Performance of Alloy‐Based Anode Materials via Ultraconformal Sb Coating–Derived Favorable Solid‐Electrolyte Interphase

“…The charge capacity of the Sb-coated porous Ge electrode is 1200 and 1010 mAh g −1 after 200 cycles at 100 and 1000 mA g −1 , which are 94% and 91% of the first charge capacity, respectively. [26] The differential capacity plots indicate that the ultraconformal Sb layer has changed the Li storage mechanism of Ge, which will be discussed later in more detail. More interestingly, compared to both differential capacity plots ( Figure S12c,d, Supporting Information), the peak located at 0.64 V, corresponding to the extraction of Li from crystal Li 15 Ge 4 to Ge, [41][42][43][44][45] disappeared after the first cycle in the Sb-coated porous Ge electrode.…”

“…[10][11][12][13][14][15][16][17][18][19][20][21] For example, the capacity of Si nanowires after 10 cycles is ≈3500 mAh g −1 , which is four times that of Si micrometer particles (≈800 mAh g −1 ). [8,10,15,[22][23][24][25][26] In the past decades, compared to the over-emphasized efforts on the electrode structure design, the understanding and engineering of the electrode/electrolyte interface have been lacking. [8,10,15,[22][23][24][25][26] In the past decades, compared to the over-emphasized efforts on the electrode structure design, the understanding and engineering of the electrode/electrolyte interface have been lacking.…”