Dielectric-Tailored Space Charge Layer and Ion Coordination Structure for High-Voltage Polymer All-Solid-State Lithium Batteries

Abstract

The poor structural stability of polymer electrolytes and sluggish ion transport kinetics of interfaces with cathode limit the fundamental performance improvements of polymer all-solid-state lithium metal batteries under high voltages. Herein, it is revealed that by introducing dielectric BaTiO₃ in an in-situ polymerized composite solid-state electrolyte, the generated interaction between the ether group of polymer electrolyte and dielectric material could effectively regulate the lithium-ion (Li⁺) coordination structure to achieve an oxidative potential higher than 5.2 V. The dielectric BaTiO₃ with spontaneous polarization also weakens the space charge layer effect between the cathode and electrolyte, facilitating fast Li⁺ transport kinetics across the cathode/electrolyte interfaces. The all-solid-state LiNi_0.8Co_0.1Mn_0.1O₂/Li batteries with the dielectric composite solid-state electrolyte exhibit an ultra-long cycling life of 1800 and 1300 cycles at room temperature under high cut-off voltages of 4.6 and 4.7 V, respectively. This work highlights the critical role of dielectric materials in high-performance solid-state electrolytes and provides a promising strategy to realize high-voltage long-life all-solid-state lithium metal batteries.