Ultrahigh Capacity Retention of a Li₂ZrO₃-Coated Ni-Rich LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Material through Covalent Interfacial Engineering

Nickel-rich LiNi0.8Co0.1Mn0.1O2 (LNCM811) is a promising lithium-ion battery cathode material, whereas the surface-sensitive issues (i.e., side reaction and oxygen loss) occurring on LNCM811 particles significantly degrade their electrochemical capacity retentions. A Li2ZrO3 coating layer can mitigate the problem by preventing these interfacial issues. However, the capacity retentions still need improvement. The normally used sol–gel coating method relies on weak hydrogen-bonding interaction between coating species (i.e., hydrated ZrO2) and cathode particles that discourages effective coating layers. Herein, we present a covalent interfacial engineering for the uniform Li2ZrO3 coating on LNCM811 materials. Experiments and density functional theory calculations indicate that the strong covalent interactions between citric acid and the Ni0.8Co0.1Mn0.1(OH)2 (NCM811) precursor effectively promote the adsorption of ZrO2 coating species on the NCM811 precursor, which is eventually converted to uniform Li2ZrO3 coating layers of about 7 nm after thermal annealing. The uniform Li2ZrO3 coating endows LNCM811 cathode materials with an exceptionally high capacity retention of 98.7% after 300 cycles at 1 C. This work shows the great potential of covalent interfacial engineering for improving the electrochemical cycling capability of Ni-rich lithium-ion battery cathode materials.