Electrolyte Design Enabling a High‐Safety and High‐Performance Si Anode with a Tailored Electrode–Electrolyte Interphase

Abstract

Silicon (Si) anodes are advantageous for application in lithium‐ion batteries in terms of their high theoretical capacity (4200 mAh g−1), appropriate operating voltage (<0.4 V vs Li/Li+), and earth‐abundancy. Nevertheless, a large volume change of Si particles emerges with cycling, triggering unceasing breakage/re‐formation of the solid‐electrolyte interphase (SEI) and thereby the fast capacity degradation in traditional carbonate‐based electrolytes. Herein, it is demonstrated that superior cyclability of Si anode is achievable using a nonflammable ether‐based electrolyte with fluoroethylene carbonate and lithium oxalyldifluoroborate dual additives. By forming a high‐modulus SEI rich in fluoride (F) and boron (B) species, a high initial Coulombic efficiency of 90.2% is attained in Si/Li cells, accompanied with a low capacity‐fading rate of only 0.0615% per cycle (discharge capacity of 2041.9 mAh g−1 after 200 cycles). Full cells pairing the unmodified Si anode with commercial LiFePO4 (≈13.92 mg cm−2) and LiNi0.5Mn0.3Co0.2O2 (≈17.9 mg cm−2) cathodes further show extended service life to 150 and 60 cycles, respectively, demonstrating the superior cathode‐compatibility realized with a thin and F, B‐rich cathode electrolyte interface. This work offers an easily scalable approach in developing high‐performance Si‐based batteries through Si/electrolyte interphase regulation.

Microscale Silicon-Based Anodes: Fundamental Understanding and Industrial Prospects for Practical High-Energy Lithium-Ion Batteries

“…179 Very recently, Zheng group developed nonflammable ether-based LHCEs with LiFSI and FEC as dual additives. 180 The results have shown that both SEI and cathode electrolyte interface (CEI) have higher elasticity and higher F content, effectively preventing electrode volume changes and continuous electrolyte decomposition (Figure 11B). As a result, full batteries paring the Si anode with commercial LiFePO 4 (LFP) and LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NMC532) showed extended cycle lives of 150 and 60 cycles, respectively, demonstrating the practical efficacy of this design.…”

“…To this end, nonflammable localized high-concentration electrolytes (LHCEs) were developed for Si-based anodes . Very recently, Zheng group developed nonflammable ether-based LHCEs with LiFSI and FEC as dual additives . The results have shown that both SEI and cathode electrolyte interface (CEI) have higher elasticity and higher F content, effectively preventing electrode volume changes and continuous electrolyte decomposition (Figure B).…”

“…(B) Schematic of the NMC532/Si full-cell with the nonflammable N-DHF electrolyte. Reprinted with permission from ref . Copyright 2021 Wiley-VCH.…”

High‐Performance Microsized Si Anodes for Lithium‐Ion Batteries: Insights into the Polymer Configuration Conversion Mechanism

“…In contrast, the Coulombic efficiency of the Si/C anode fluctuates greatly, indicating instability of the solid electrolyte interface. [ 39 ] At different current densities (0.33, 0.66, 1.65, 3.3, 6.6, and 16.5 A g –1 ), the specific capacity of the PCSi‐2 anode is 2038.6, 2088.5, 1845.9, 1550.5, 1118.4, and 417.9 mAh g –1 , respectively (Figure 5c). When the current density returns to 0.33 A g –1 , the remaining capacity is 95% of its initial capacity.…”

An electrolyte for SiOx/LiNi0.5Mn1.5O4 batteries

“…These materials provide a wide potential window and form a passivation lm (solid electrolyte interphase, SEI) on the anode surface, retarding the electrolyte degradation kinetically by blocking direct contact between the electrode and electrolyte. For instance, ether-based electrolytes (such as 1,2dimethoxyethane (DME) and tetrahydrofuran) 3,10 and uorinated solvent-based electrolytes (such as uoroethylene carbonate (FEC)) 11,12 were applied to improve the reversibility of SiO x and LiNi 0.5 Mn 1.5 O 4 , respectively. Nevertheless, to the best of our knowledge, a stable SiO x |LiNi 0.5 Mn 1.5 O 4 battery has not been achieved due to the absence of electrolytes guaranteeing high reduction and oxidation stabilities.…”