# Interfacial Li+ Diffusion Booster Accelerated by Enhanced Metal‐Organic Framework Sieving and Wettability for High‐Voltage Solid‐State Lithium Metal Batteries

## TL;DR

This paper introduces a new solid-state battery electrolyte that improves lithium ion transport and prevents dendrite growth, leading to longer battery life and better performance.

## Contribution

A novel solid-state polymer electrolyte with metal-organic frameworks and ionic liquid is developed to enhance Li+ transport and interfacial wettability.

## Key findings

- The PIM electrolyte achieves 3.1 mS cm−1 ionic conductivity and a Li+ transference number of 0.65.
- Symmetric Li metal cells operate stably for over 1000 hours with 25 mV voltage hysteresis.
- The electrolyte shows 85.5% and 96.5% capacity retention with high-voltage cathodes after 120 and 400 cycles.

## Abstract

Solid‐state lithium metal batteries (SSLMBs) are promising for realizing higher energy density. However, the poor interfacial Li+ transport kinetics and Li dendrite growth inhibit SSLMBs, leading to sluggish interfacial ion diffusion and depressive lifespan, which is attributed to high barriers blocked by anions or interface space in solid‐state electrolytes. Herein, a flexible solid‐state polymer skeleton employed with ionic liquid and metal‐organic frameworks (PIM) electrolyte is proposed to strengthen interfacial Li ion exchange by improving the Li+ sieving effect and interfacial wettability. Thanks to the immobilization effect of TFSI− anions affected by positive metal atom centers and pore morphology, the PIM electrolyte exhibits exceptional properties, i.e., a high ionic conductivity up to 3.1 mS cm−1 at 60 °C and an improved Li+ transference number of 0.65, enabling symmetric cells of Li metal to run steadily for over 1000 h with lower voltage hysteresis (25 mV). Meanwhile, matching with high‐voltage electrodes, the solid‐state PIM electrolyte exhibits good compatibility and stability toward LiNi0.6Co0.2Mn0.2O2 and LiFePO4 electrodes, showing the capacity retentions of 85.5% and 96.5% after 120 and 400 cycles, respectively. This work suggests low interfacial diffusion resistances and high compatibility for make it a promising candidate for future solid‐state battery.

An ion‐selective SSE is proposed with an accelerated Li+ migration feature, where the metal organic framework functions as a molecular sieve to selectively block bulky anions and the ionic liquid acts as Li ion bridge. Consequently, The as‐prepared full cell exhibited high capacity and retention under the upper voltage of 4.3 V.© 2025 WILEY‐VCH GmbH