Freestanding cathodes with vertically arranged microchannels via phase inversion for quasi-solid-state lithium metal batteries

Gel polymer electrolytes (GPEs) exhibit significant potential in the development of lithium metal batteries owing to their safety and electrochemical stability. To achieve high-energy-density lithium metal batteries, it is of great significance to optimize the electrode structure to adapt the GPE. This work proposes a freeze-drying phase inversion (PI) technique to create a freestanding cathode with low tortuosity and vertically arranged microchannel structures. This unique architecture facilitates efficient lithium-ion transport and improves the wettability between the electrode and the electrolyte. Consequently, the LiFePO4 (LFP)/Li half-cell with an active material loading of 9.5 mg cm−2 exhibits a high discharge capacity (158.6 mA h g−1, with 96.3% retention after 250 cycles at 0.5C at room temperature). When integrated with in situ polymerized poly(1,3-dioxolane) (PDOL) gel electrolyte, the Li|PDOL-gel|PI-LFP battery with an active material loading of 9.5 mg cm−2 achieves a high discharge capacity of 132.47 mA h g−1 after 100 cycles at 0.5C at room temperature. At the same time, the kinetic transport in the interface is improved, reducing polarization and retaining high capacity at high discharging current density.