Addressing crystal defects and lattice strain challenges in Ni-rich cathodes necessitates a holistic consideration of the heterogeneous cathode microstructure and large anisotropic volume changes driven by Li transport. This calls for a fundamental consideration of composition design and microstructure regulation. Our findings underscore the potential of morphological optimization and a controlled rate of Li (de)intercalation as chemistry-agnostic strategies to enhance stability against oxygen loss. As shown in Fig. , b, reducing the secondary particle diameter to below 4 µm can effectively mitigate the capacity fading issue observed in conventional polycrystalline cathodes . Reducing the diameter of secondary particles from 9 µm to below 4 µm enables the increase of the discharge rate from 1 C to 5 C while maintaining the same 90% usable capacity. This improvement is attributed to the effective shortening of the Li intercalation path and a reduced accumulation of crystalline defects, such as dislocations, during battery operation. TEM analysis further supports these findings, suggesting that reducing the charge rate to below 0.1 C or decreasing the particle size to 1 µm can mitigate structural defects and microcracks, thereby enhancing the cycling stability of Ni-rich NMC cathodes . Moreover, the simulation results presented in Fig. and Fig. indicate that employing single crystal cathodes can significantly reduce the formation of dislocations and mitigate oxygen-loss-related structural degradation in Ni-rich NMC cathodes. Differential electrochemical mass spectroscopy characterisation and HRTEM characterisation also reveal that the formation of rock-salt phase in the bulk of cathodes is considerably reduced in single crystal Ni-rich cathodes, compared to polycrystalline cathodes . Therefore, the improved chemomechanical and cycling performance of single crystal NMC cathodes can be attributed to both the elimination of intergranular cracks and the reduction in defects-induced bulk structural degradation. Fig. shows that using a single type of solid electrolytes cannot simultaneously mitigate the large tensile stress buildup in NMC cathodes and on the interfaces between these cathodes and the solid electrolytes. This often leads to either the formation of intergranular cracks within the cathodes or contact loss along the cathode/solid-electrolyte interfaces. Therefore, hybrid systems that involve both oxides and polymer electrolytes seem to be a promising solution to address the mechanical degradation issues in solid state batteries . Furthermore, preventing cation disordering emerges as a potent means to inhibit the structural changes required to accommodate oxygen vacancies. For instance, the ribbon superstructure, as opposed to the honeycomb superstructure in TM metal layers within sodium-ion intercalation cathodes proves capable of suppressing manganese disorder and the associated oxygen molecule formation, during the P2 to O2 phase transition involving slab gliding .