In situ Crystal Structure Growth and Control for Enhancing Comprehensive Performance in Ultra-High Nickel-Layered...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ultra-high nickel-layered cathodes (LiNi$_{x}$Co$_{y}$Mn$_{1-x-y}$O$_{2}$, x ≥ 0.9) are promising for next-generation batteries due to high energy density and low cost.
• Commercialization is hindered by structural degradation and poor Li$^{+}$ transport in dense secondary particles.
• Existing materials face challenges in cycle stability, rate performance, and high-voltage/temperature operation.

Purpose of the Study:

• To modulate the intrinsic structure and morphology of ultra-high nickel cathodes.
• To controllably synthesize a gapped-structure cathode with a thin surface rock-salt phase (G-Ni91).
• To enhance electrochemical performance, including capacity, cycle stability, and rate capability.

Main Methods:

• In situ growth method for intrinsic structural modulation.
• Controlled synthesis of gapped-structure cathode (G-Ni91) with a thin surface rock-salt phase.
• Multiscale characterizations to analyze structural and electrochemical properties.

Main Results:

• G-Ni91 exhibits superior initial capacity, cycle stability, rate performance, and high-voltage/temperature operation compared to dense-structure cathodes (D-Ni91).
• Smaller primary particle size, gapped interspace, and reduced Li$^{+}$/Ni$^{2+}$ antisite defects in G-Ni91 enhance Li$^{+}$ transport dynamics.
• A thin surface rock-salt phase and more uniform primary particles contribute to improved cycling stability.

Conclusions:

• The developed G-Ni91 cathode with intrinsic structural design and modification offers a feasible pathway for improved electrochemical performance.
• The gapped structure and thin rock-salt phase are key factors in enhancing lithium-ion dynamics and stability.
• This work provides a novel approach for designing advanced ultra-high nickel-layered cathodes for high-performance batteries.