Electrolyte Design Enabling a High‐Safety and High‐Performance Si Anode with a Tailored Electrode–Electrolyte Interphase
Zhang Cao, Xueying Zheng, Qunting Qu, Yunhui Huang, Honghe Zheng
Abstract
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 LiFePO 4 (≈13.92 mg cm −2 ) and LiNi 0.5 Mn 0.3 Co 0.2 O 2 (≈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.