Failure-mode-oriented design of cathode materials for practical lithium-ion batteries: from crystal stability to...

Cathode materials remain the primary determinant of the energy density, voltage output, lifetime, safety, and cost of lithium-ion batteries. Although conventional reviews usually classify cathodes according to crystal structures or chemical compositions, practical battery degradation is rarely governed by structure alone. Instead, capacity fading, impedance growth, oxygen loss, transition-metal dissolution, interfacial parasitic reactions, and particle cracking usually occur simultaneously and are strongly coupled with electrode processing and operating conditions. This review discusses lithium-ion battery cathode materials from a failure-mode-oriented perspective, covering high-voltage LiCoO₂, spinel LiMn₂O₄, olivine LiFePO₄, and Ni-rich layered oxides. Rather than simply summarizing individual modification methods, it emphasizes how doping, coating, surface reconstruction, morphology regulation, and gradient design address specific degradation pathways. Particular attention is paid to the transition from material-level optimization to practical-cell durability, including electrolyte-dependent cathode-electrolyte interphase formation, cathode-anode crosstalk in full cells, thick-electrode transport, high-voltage interface compatibility, and chemo-mechanical stability. Finally, future directions are proposed for developing cathodes that combine high capacity, long cycle life, scalable processing, and practical safety.