Stabilization Strategies and Degradation Mechanisms of Ni-rich Layered Oxide Cathodes for Lithium-ion Batteries

This thesis investigates Ni-rich layered oxide cathodes for high-performance lithium-ion batteries. Li-ion batteries are widely used in electric vehicles and large-scale energy storage because of their high energy density and cost efficiency. However, the commercial deployment of Ni-rich cathodes is hampered by surface instability, lattice distortion, impedance increase, and rapid capacity fade. To address these challenges, this work develops an integrated materials stabilization strategy targeting both interfacial and structural degradation. Three complementary approaches were explored: Li⁺-conducting surface coatings, bulk anion–cation co-doping, and removal of surface impurities. Operando structural characterization and electrochemical analyses were employed to establish structure–property–performance relationships.
In our studies we find that; An LATP coating improves Li⁺ transport, while suppressing charge-transfer resistance growth and lattice strain. Fluorine–chromium co-doping stabilizes the layered framework, reduces cation disorder, and significantly slows impedance increase. Acid treatment that removes residual carbonates further enhances interfacial stability and enables more reliable high-voltage cycling. A comparison between LATP and Al2O3 coatings reveals a fundamental trade-off between interfacial kinetics and long-term chemical stability. These findings provide practical design guidelines for durable Ni-rich cathodes. Future work should integrate these strategies and validate them under realistic full-cell conditions to accelerate commercial application.