Intergrown multi-phase composite oxides are critical for LiPS adsorption.

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Nickel-rich layered oxides have been regarded as a potential cathode material for high-energy-density lithium-ion batteries because of the high specific capacity and low cost. However, the rapid capacity fading due to interfacial side reactions and bulk structural degradation seriously encumbers its commercialization. Herein, a highly stable hybrid surface architecture, which integrates an outer coating layer of TiO2&Li2TiO3 and a surficial titanium doping by incorporated Ti2O3, is carefully designed to enhance the structural stability and eliminate lithium impurity. Meanwhile, the surficial titanium doping induces a nanoscale cation-mixing layer, which suppresses transition-metal-ion migration and ameliorates the reversibility of the H2 → H3 phase transition. Also, the Li2TiO3 coating layer with three-dimensional channels promotes ion transportation. Moreover, the electrochemically stable TiO2 coating layer restrains side reactions and reinforces interfacial stability. With the collaboration of titanium doping and TiO2&Li2TiO3 hybrid coating, the sample with 1 mol % modified achieves a capacity retention of 93.02% after 100 cycles with a voltage decay of only 0.03 V and up to 84.62% at a high voltage of 3.0–4.5 V. Furthermore, the ordered occupation of Ni ions in the Li layer boosts the thermal stability by procrastinating the layered-to-rock salt phase transition. This work provides a straightforward and economical modification strategy for boosting the structural and thermal stability of nickel-rich cathode materials.

Lithium-rich cathode oxides exhibit extraordinary specific capacities that are mainly ascribed to the accumulated redox reactions of anions and cations at high operating potentials. However, rapid capacity fading and voltage decay have been impeding the commercialization process. Herein, we report a surface integration strategy to improve the capacity and voltage stability of a Co-free lithium- and manganese-rich (LMR) cathode oxide Li1.2Ni0.2Mn0.6O2, by which the spinel phase and surface cobalt gradient doping are synchronously built on the surface of LMR microspheres. The spinel phase and surface cobalt gradient doping surface integration inhibit irreversible phase transformation (layered to spinel or rock-salt structure), promote lithium-ion diffusion, and improve the LMR cathode surface stability. This surface integration design enables a striking reversible discharge capacity of 280.05 mA h g–1 at 0.1 C and a superior cycling performance with a retention of 94.56% at 0.5 C after 200 cycles. Besides, the modified LMR cathode still exhibits an excellent specific capacity of 127.06 mA h g–1 at 10 C. This surface integration strategy opens a new scope for lithium-ion batteries with high energy density for practical applications in the near future.