High Rate Capability and Cycling Stability in Multi-Domain Nanocomposite LiNi_{1- x}Ti_{3 x /4}O₂ Positive Electrodes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium nickel oxide (LiNiO2) is a key positive electrode material for lithium-ion batteries, but its practical application is limited by poor cyclability and structural degradation.
• Increasing energy demands necessitate the development of advanced battery materials with improved stability and performance.
• Titanium (Ti4+) substitution is explored as a strategy to enhance the structural integrity and electrochemical properties of LiNiO2.

Purpose of the Study:

• To synthesize and characterize a novel LiNi1-xTix/4O2 solid solution by substituting Ti4+ into LiNiO2.
• To investigate the structural stabilization mechanism and electrochemical performance of the Ti-substituted LiNiO2.
• To evaluate the potential of these materials for high-energy and high-power lithium-ion battery applications.

Main Methods:

• Synthesis of LiNi1-xTix/4O2 solid solutions for 0.025 ≤ x ≤ 0.2 using solid-state reactions.
• Structural characterization using X-ray diffraction (XRD), neutron diffraction, and scanning transmission electron microscopy (STEM).
• Electrochemical evaluation including cycling stability, rate capability, and performance at high electrode mass loadings.

Main Results:

• Compositions formed stable nanocomposites of ordered and disordered rock salt domains, effectively suppressing detrimental phase transitions.
• The Ti-substituted material demonstrated excellent structural reversibility and enabled deep delithiation without degradation.
• The composition x = 0.075 (LiNi0.925Ti0.05625O2) achieved 93% capacity retention after 100 cycles and high reversible capacities (125 mAh g-1) even at high rates (3200 mA g-1).

Conclusions:

• Ti4+ substitution into LiNiO2 effectively stabilizes the structure, leading to a low-strain positive electrode material with enhanced cyclability and high-rate capability.
• The developed LiNi0.925Ti0.05625O2 exhibits performance characteristics suitable for commercial lithium-ion battery applications, particularly at high electrode mass loadings.
• This work presents a promising strategy for developing next-generation high-performance lithium-ion battery electrode materials.