Surface Gradient Ni-Rich Cathode for Li-Ion Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Nickel-rich layered oxide cathode materials, LiNi_xCo_yMn_zO₂ (NCM), offer high capacity for lithium-ion batteries (LIBs).
• Practical application is hindered by interface instability, phase transitions, and capacity fade.

Purpose of the Study:

• To develop a simple, scalable method for preparing gradient cathode materials (M-NCM) with enhanced structural stability and rate performance.
• To address capacity loss and interface issues in NCM cathode materials for LIBs.

Main Methods:

• A facile and scalable synthesis approach utilizing coordination of Ni²⁺ with ammonia and reduction of KMnO₄.
• In situ construction of gradient compositional design in the NCM cathode.

Main Results:

• The M-NCM cathode exhibited improved structural stability, mitigating Li/Ni mixing and parasitic surface reactions.
• Achieved 98.6% capacity retention after 200 cycles and 107.5 mAh g^-1 at 15 C charge rate.
• A 1.2 Ah pouch cell demonstrated over 500 cycles with only 8% capacity loss.

Conclusions:

• The gradient compositional design is crucial for stabilizing the crystal structure and enhancing electrochemical performance.
• This work presents a viable strategy for fabricating advanced gradient cathode materials for high-performance LIBs.