Reversibility of H2-H3 Phase Transition in High-Nickel Layered Oxide Cathodes

초록

High-nickel layered oxide cathodes offer enhanced energy density for lithium-ion batteries (LIBs)but suffer from severe degradation associated with the H2-H3 phase transition during high-voltage operation. This structural transformation, characterized by abrupt c-axis contraction near 4.2 V versus Li/Li+, generatesanisotropic lattice strain that initiates microcrack formation, electrolyte penetration, and surface reconstruction,with severity intensifying beyond 80% nickel content. This review systematically examines the fundamentalstructural features governing H2-H3 phase transitions, elucidates the mechanistic coupling between this transformationand degradation pathways spanning mechanical fracture to chemical instability, and critically evaluatesmitigation strategies encompassing compositional modifications through bulk doping and surface coating,alongside electrochemical interventions including advanced electrolyte formulations and processing optimization. The synthesis of current understanding reveals that achieving reversible H2-H3 behavior in ultra-highnickelcompositions requires synergistic integration of multiple strategies, with future progress demandingadvanced characterization, predictive computational frameworks, and holistic optimization balancing performance,cost, and scalability for practical deployment.

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