Fabrication of Homogeneous Nanometer-Thin Artificial CEI on LNMO by Suspension Coating of Niobate Nanosheets.

Abstract

Lithium-ion batteries (LIBs) require stable high-voltage cathode materials to meet escalating energy storage demands. LiNi0.5Mn1.5O4 (LNMO) offers high energy density while employing earth-abundant manganese but suffers from degradation due to manganese dissolution and electrolyte decomposition at elevated voltages. This work presents a facile water-based process to coat LNMO particles with nanometer-thin niobate nanosheets via electrostatically driven self-assembly. As nanosheets of large aspect ratio (≈2000) are obtained by a spontaneous delamination yielding uniform thickness (1.8 nm), the coating consistently covers LNMO surfaces. Electrochemical testing in full-cells showed improved cycle stability, enhanced rate capability, and reduced self-discharge for coated LNMO compared to pristine material. Post-cycling analyses revealed suppressed manganese migration to the anode, evidencing the coating's effectiveness as a Li-ion-conductive, chemically inert permselective membrane that mitigates detrimental side reactions. The modified LNMO/graphite full cells exhibit excellent cycling stability, retaining 91% of its initial capacity after 500 cycles at 1C, as compared to 42% for the pristine material. Additionally, the coated material shows an increased rate capability, with a capacity of 101 mAh g-1 at 5C as compared to 84 mAh g-1 of the uncoated. This scalable, cost-effective, coating strategy extends cathode lifespan and offers a promising route for advancing high-voltage LIB technology.