Stress Relief Principle of Micron-Sized Anodes with Large Volume Variation for Practical High-Energy Lithium-Ion Batteries

Abstract

Practical applications of high gravimetric and volumetric capacity anodes for next-generation lithium-ion batteries have attracted unprecedented attentions, but still faced challenges by their severe volume changes, rendering low Coulombic efficiency and fast capacity fading. Nano and void-engineering strategies had been extensively applied to overcome the large volume fluctuations causing the continuous irreversible reactions upon cycling, but they showed intrinsic limit in fabrication of practical electrode condition. Achieving high electrode density is particularly paramount factor in terms of the commercial feasibility, which is mainly dominated by the true density and tapping density of active material. Herein, based on finite element method calculation, micron-sized double passivation layered Si/C design is introduced with restrictive lithiation state, which can withstand the induced stress from Li insertion upon repeated cycling. Such design takes advantage in structural integrity during long-term cycling even at high gravimetric capacity (1400 mAh g(-1)). In 1 Ah pouch-type full-cell evaluation with high mass loading and electrode density (approximate to 3.75 mAh cm(-2)and approximate to 1.65 g cm(-3)), it demonstrates superior cycle stability without rapid capacity drop during 800 cycles.