Constructing ternary hybrid interface with rapid Li+ conductivity to enable subzero-temperature Si-C||LCO pouch cell at −40 ℃

Abstract

Subzero temperature severely forbids the transfer of lithium ion (Li+) between electrodes and the diffusion of Li+ in interphase, which become one of the slowest steps. Especially in silicon-based battery systems, the continuous thickening and poor ionic conductivity of interface make this challenge more prominent. Maintaining a thin interface with superior ionic conductivity is an effective strategy to develop low temperature silicon-based batteries. Herein, a ternary hybrid solid electrolyte interface containing F, N, S was constructed by electrolyte design to improve Li+ interface transport kinetics. Benefited from robust mechanical property of inorganics and high ionic conductivity of Li3N and LixSOy, the hybrid interface sustains a thin thickness over cycles and behaves significantly reduced energy barrier for Li+ diffusion. Thus, such interface enables Si-C||LCO pouch cell to maintain a high capacity retention of 56.4 % of the room-temperature capacity at −30℃, and retain 87.4 % of the capacity after 200 cycles. Even at −40℃ and a high loading of 3mAh/cm2, the cell can still be charged and provide a specific capacity of about 310 mAh/g with almost no capacity attenuation after 50 cycles. This work demonstrates the important role of excellent interface for low temperature silicon-based batteries, and provides a reference for the design of rapid Li+ transport interface.