Exploring the chemical adhesive effect of tin foil to double the lifetime of the solid-state lithium battery

Abstract

The growth of lithium dendrite in solid-state electrolytes (SSE) poses a significant challenge to the commercialization of solid-state battery (SSB). While previous research has largely concentrated on enhancing the ionic conductivity and electrochemical stability of SSE, the mechanical properties of the SSE/Li interface, a critical factor in suppressing dendrite initiation and propagation, have received inadequate attention. To address this gap, this work develops an interface modification strategy to enhance both adhesion and elasticity at the SSE/Li interface, thereby ensuring a robust interface during prolonged cycling. Specifically, tin foil is introduced into the SSE/Li interface to form the Li-Sn alloy during cycling. The resulted Li-Sn alloy ensures intimate SSE/Li contact through chemical adhering effect and simultaneously provides a 35-fold increase in elasticity compared to cycled Li electrode, effectively inhibiting the growth of Li-dendrite. Furthermore, the introduction of tin foil mitigates the occurrence of side reactions at SSE/Li interface. As a result, the LFP/LATP/Sn/Li cell (300 cycles, 83.9% capacity retention) demonstrates doubled lifetime of LFP/LATP/Li cell (155 cycles, 80% capacity retention) at 0.5 C. Moreover, the full cell and symmetrical cell exhibits robust cycling performance at higher rate, sustaining over 300 cycles at 1.5 C and 400 h at 0.5 mA/cm². Compared with previous studies, this work not only emphasizes the critical role of the mechanical properties of the SSE/Li interface in determining interface stability, but also provides a valuable guide to how the lithium alloy interlayer enhances electrochemical stability.