Anionic and cationic co-driving strategy for enhanced lithium storage and migration on Si-based anodes

Abstract

Alloy-based anodes are considered to be a promising choice for next-generation high-energy density devices; nevertheless, lithiation-induced anisotropic swelling and ongoing solid electrolyte interphase growth and cracking severely limit practical applicability. Herein, an anionic and cationic co-driving strategy is proposed for the alloy-based (Si) anode that aims to improve structural stability with controlled ion migration pathways and enhanced reaction kinetics, eventually leading to better capacity, high-rate performance, and cycle performance for lithium storage. Ex-situ tests and density functional theory simulations show that Co-HHTP has both anionic and cationic co-storage capabilities. Furthermore, the strong interactions between Co-HHTP and anionic species may impede anion transport towards the silicon surface, hence mitigating the recurrent degradation of the solid electrolyte interphase. As a proof of concept, the Si-based anode, fitted with Co-HHTP, delivers a high initial Coulombic efficiency of 80.4 %, a large reversible capacity (1648.0 mAh g−1 at 0.2 A g−1), and an ultralow attenuation rate of 0.034 % per cycle over 1000 cycles. The proposed approach provides a new strategy for a high-performance anode through functional coating structural construction coupled with anionic and cationic co-storage that confine anion diffusion and facilitate lithium storage and migration.