Tuning electronic structure of MOF-based solid-state electrolytes to activate dormant lithium and facilitate ion transport kinetics towards lithium metal batteries

Abstract

The cycling lifespan of high-energy solid-state lithium metal batteries is predominantly limited by the degradation of Li⁺ kinetics during cycling. In this study, we propose an innovative solid-state electrolyte system that integrates Li activation with interface engineering. A Ti–Co-based bimetallic metal–organic framework host membrane with abundant catalytic sites is developed, effectively activating dormant Li. Meanwhile, in situ polymerization is employed to optimize the compatibility between the membrane and the electrode interface. This design leverages spontaneous redox processes to effectively enhance interfacial charge-transfer kinetics, adjust the local coordination environment of Li⁺, and promote Li⁺ transport dynamics, thus boosting the utilization of electroactive Li⁺. The unique host membrane enables Li||Cu cells to achieve an average utilization rate of 97% for Li⁺. The resulting asymmetrical cell exhibits an impressive cycle life of 1000 hours at a practical current density of 1 mA cm⁻² with a low overpotential. When paired with various cathodes, it delivers stable and highly reversible capacity. Specifically, the assembled NCM90 batteries demonstrate a high reversible capacity of 225.7 mA h g⁻¹ at 0.1C and good cycling stability over 200 cycles at 1C. This finding breaks the conventional strategies aimed at improving the overall performance of solid-state lithium metal batteries and significantly enhances active Li⁺ utilization efficiency during cyclic kinetic processes.