High-Performance All-Solid-State Lithium Batteries Enabled by a Highly Adhesive Dry-Processable Binder

Abstract

All-solid-state lithium batteries (ASSLBs) have emerged as a promising solution to the safety concerns associated with traditional lithium-ion batteries. In sulfide-based ASSLBs, polytetrafluoroethylene (PTFE) binder is typically used for fabricating sheet-type composite cathodes via a solvent-free dry process. However, PTFE presents limitations in achieving desirable cycling stability and high-rate performance.  In this study, we introduce a highly adhesive dry-processable binder, poly(tetrafluoroethylene-co-2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole) (P(TFE-TTD)), designed to enhance electrochemical performance of ASSLBs. The all-solid-state lithium cell assembled using Li6PS5Cl electrolyte, composite LiNi0.8Co0.1Mn0.1O2 cathode employing P(TFE-TTD) binder demonstrated an impressive discharge capacity of 183.8 mAh g⁻¹ (2.2 mAh cm⁻²), with superior cycling stability of 87% retention after 200 cycles at 0.5 C and 25 °C.  This  improved performance is attributed to enhanced interfacial adhesion between cathode components and reduced electrical resistance within the composite cathode. Our findings highlight the potential of P(TFE-TTD) as an effective binder material for preparing high-performance dry-processed composite cathodes in the all-solid-state batteries.

Keywords: All-solid-state batteries, Composite cathode, Sulfide electrolyte, Dry processing, Polymer binder