Enhanced Cyclability of Cr8O21 Cathode for PEO-Based All-Solid-State Lithium-Ion Batteries by Atomic Layer Deposition of Al2O3

Cr8O21 can be used as the cathode material in all-solid-state batteries with high energy density due to its high reversible specific capacity and high potential plateau. However, the strong oxidation of Cr8O21 leads to poor compatibility with polymer-based solid electrolytes. Herein, to improve the cycle performance of the battery, Al2O3 atomic layer deposition (ALD) coating is applied on Cr8O21 cathodes to modify the interface between the electrode and the electrolyte. X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy, etc., are used to estimate the morphology of the ALD coating and the interface reaction mechanism. The electrochemical properties of the Cr8O21 cathodes are investigated. The results show that the uniform and dense Al2O3 layer not only prevents the polyethylene oxide from oxidization but also enhances the lithium-ion transport. The 12-ALD-cycle-coated electrode with approximately 4 nm Al2O3 layer displays the optimal cycling performance, which delivers a high capacity of 260 mAh g(-1) for the 125th cycle at 0.1C with a discharge-specific energy of 630 Wh kg(-1).

Automated summary

In this study, Al2O3 atomic layer deposition (ALD) coating was applied on Cr8O21 cathodes to improve the cycle performance of all-solid-state batteries. The uniform and dense Al2O3 layer not only prevented polyethylene oxide oxidation but also enhanced lithium-ion transport. The electrode coated with approximately 4 nm Al2O3 layer after 12 ALD cycles exhibited optimal cycling performance, delivering high capacity and discharge-specific energy.