Advanced modification strategies for improving the thermal stability of Ni-rich layered cathodes towards next-generation lithium-ion batteries

Driven by the ever-growing demand for the explosive growth of electric devices, Ni-rich layered cathodes (NRLCs) have attracted extensive interest due to their superior reversible capacity and relatively low cost. However, the inferior thermal stability of NRLCs severely affects their large-scale application. Thermal runaway (TR) is a critical safety issue that impedes the further commercialization of high-energy lithium-ion batteries (LIBs). Therefore, understanding the thermal stability of NRLCs is of great significance for rational design and improvement of high-energy cathodes towards safer next-generation LIBs. Herein, advanced design strategies for boosting the thermal stability of NRLCs are reviewed in detail, including elemental doping, surface coating, concentration-gradient structure, single-crystal technology, microstructure engineering, and synergistic modification. Finally, conclusions and the major challenges and prospects worth exploring for further enhancing the thermal stability of NRLCs are proposed. Notably, synergistic modification strategies integrating high-entropy doping with surface coating in single-crystal NRLCs are effective approaches to significantly enhance the thermal stability, and the corresponding synergistic mechanisms remain to be urgently probed. The purpose of this review is to inspire further research into the safety of NRLCs featuring higher energy density, generating attention from both academia and industry to accelerate the commercialization of NRLCs and advance the sustainable development of high-energy LIBs.