Enabling an Intrinsically Safe and High-Energy-Density 4.5 V-Class Lithium-Ion Battery with Synergistically Incorporated Fast Ion Conductors

The Ni-rich layered oxide cathode is pushing the frontier of battery powered electric vehicles toward longer driving range and lower cost, whilst facing a major challenge with the compromised cycle life and thermal robustness. It is well recognized that irreversible oxygen evolution at the cathode-electrolyte interphase is critical to the electrochemical and thermal stability of the Ni-rich cathode. Herein, combining experiments with density functional theory (DFT) calculations, the authors focus on manipulating the irreversible oxygen evolution to solve the performance degradation and safety hazard. An oxygen ion conductor introduced to the surface of the cathode restrains the activated surficial lattice oxygen ions by its stable oxygen vacancies. Meanwhile, a Li-rich fast ion conductor incorporated in the coating layer synergistically reinforces the Li diffusion path through the cathode-electrolyte interphase. This sophisticated multifunctional surficial modification implemented by a neat one-step treatment represents a successful design and development of a thermally stable Ni-rich cathode and approximately 400-cycle state-of-health up to 80% with the operating voltage range extended up to 4.5 V. Therefore, this study provides an encouraging strategy to overcome the capacity versus robustness dilemma of high-energy cathodes.