Presentation Title：Deciphering the synergistic mechanism for thermal stability improvement in Ni-rich single-crystal cathode materials via LiNbO₃ coating and Nb⁵⁺ surface doping.

 Abstract：

Ni-rich layered cathode materials are among the most promising candidates for next-generation lithium-ion batteries (LIBs) due to their high specific capacity and energy density. However, their poor intrinsic thermal stability and the resulting risk of thermal runaway remain major obstacles to safe large-scale application. In this work, we present a synergistic modification strategy that integrates LiNbO3surface coating with Nb5+surface doping to simultaneously enhance the electrochemical and thermal stability of single-crystal NCM811 cathode materials. The modified Nb@SC-NCM811 material was synthesizedviapowder atomic layer deposition (PALD) followed by high-temperature sintering. Electrochemical tests demonstrate that Nb@SC-NCM811 achieves improved cycling stability and higher capacity retention compared with pristine SC-NCM811. Thermal characterization using DSC, TG-MS, C80 micro-calorimetry, and ARC reveals a higher decomposition onset temperature, reduced oxygen release, and significantly lower heat generation, thereby improving overall cell safety. Advanced characterization with aberration-corrected TEM (AC-TEM) and density functional theory (DFT) calculations further elucidates the microscopic mechanisms: LiNbO3 coating mitigates side reactions at the electrode-electrolyte interface, while Nb5+doping strengthens Nb-O bonds, increases oxygen vacancy formation energy, and raises migration barriers for transition metal cations, delaying structural degradation under heat induction. This work not only clarifies the Nb-modification mechanism at the atomic scale but also provides a rational pathway for designing safer, high-energy-density cathodes. The results highlight the critical role of synergistic structural modification in advancing the thermal safety of Ni-rich LIBs.

Bio:

Qingsong Wang, Ph.D., is a Professor at the State Key Laboratory of Fire Science, University of Science and Technology of China (USTC). He has over 20 years of research experience in lithium-ion battery safety, focusing on thermal runaway mechanisms and fire prevention technologies. He has led more than 40 projects, including the National Key R&D Program of China, National Natural Science Foundation of China (NSFC) projects, and major enterprise collaborations. He has published over 200 papers in top journals such as Nature Communications and Progress in Energy and Combustion Science, with more than 20,000 citations. Professor Wang is a Fellow of the Royal Society of Chemistry (FRSC) and the Institution of Engineering and Technology (FIET), and recipient of multiple national awards for scientific and technological innovation.