Porous Lithiophilic Li-Si Alloy-Type Interfacial Framework via Self-Discharge Mechanism for Stable Lithium Metal Anode with Superior Rate

Abstract

Lithium is regarded as an ideal anode for next-generation Li metal batteries (LMB) as it exhibits extraordinarily high theoretical capacity and the lowest electrochemical potential among all anode candidates. However, safety concerns and poor cycling stability of Li induced by uncontrollable dendrite growth and severe side reactions impede its practical application for LMB. Although various strategies for fabricating Li anodes have been suggested, developing high-rate LMB remains a significant challenge. To address this challenge, the use of a 3D porous Li-Si alloy-type interfacial framework (LSIF) created via a "self-discharge" mechanism with the aid of an electrolyte is proposed here. Exploiting the in situ spontaneous prelithiation, lithiophilic Li15Si4 particles are homogenously arranged to build porous 3D LSIF. The balanced ionic/electronic conducting LSIF serves as a stable Li host, helping to suppress dendrite growth and volume expansion during cycling. The LSIF@Li anode possesses a strong affinity toward Li, rapid Li diffusion kinetics, and low nucleation/diffusion barriers. Moreover, the LSIF@Li symmetric cells are capable of stable cycling (over 1000 cycles) even at an ultrahigh current density (15 mA cm(-2)). When paired with LiNi0.5Co0.2Mn0.3O2 or LiFePO4, LSIF@Li full cells show improved rate capability and long-term cycling stability (approximate to 2000 cycles) at 10 C.