Dual-dimensional regulation of interface and stress via a composite anode for stable gel-based solid-state lithium metal batteries

Abstract

Solid-state electrolyte lithium (Li) metal batteries have been considered as promising storage devices due to their high energy density, good thermal stability and safety. The key to achieving their superior performance lies in maintaining a stable solid–solid interface. Although applying high pressure is a common strategy to improve interfacial contacts, the generally poor pressure tolerance of the Li metal anode has largely been overlooked by researchers. Under high pressure, the Li anode undergoes significant volume changes and creep, which not only fails to maintain intimate contact but also intensifies interface separation, ultimately leading to performance degradation. Herein, a gel polymer electrolyte (GPE)/Li metal/carbon fiber cloth (CFC) composite anode (G-LiCFC) with high pressure resistance capability was fabricated by the hot-melting method. The G-LiCFC composite anode not only maintains structural integrity under a high pressure of 30 MPa but also contributes to forming an excellent interface with the electrolyte. As a result, the symmetric cells of the G-LiCFC composite anode display stable cycling for 4870 hours at a high areal capacity of 12 mA h cm⁻², and the LiFePO₄|GPE|LiCFC full cells exhibit excellent cycling performance with no capacity decay after 410 cycles at 0.2 C under a high pressure of 10 MPa.

Keywords: Solid-state electrolyte; Li metal; Carbon fiber cloth/lithium metal composite; Compressive resistance; Interface.