Cracking Mechanism and Inhibition Strategies of Polycrystalline NCM Electrode Particles

Area of Science:

• Materials Science
• Electrochemistry
• Computational Mechanics

Background:

• High-energy-density cathode materials like lithium nickel cobalt manganese oxides (NCM) are vital for electric vehicles and energy storage.
• Particle cracking in NCM cathodes due to lithium-ion diffusion-induced stress limits battery performance and lifespan.
• Current research faces challenges in capturing cracking evolution and fully understanding NCM polycrystalline particle cracking mechanisms.

Purpose of the Study:

• To develop an advanced computational model for simulating NCM polycrystalline particle cracking.
• To investigate the role of anisotropic volume contraction in the cracking behavior of NCM particles.
• To propose strategies for inhibiting or mitigating particle cracking and enhancing mechanical stability.

Main Methods:

• Development of an anisotropic polycrystalline fracture phase-field model (AP-FPFM).
• Coupling of the model with lithium-ion diffusion, mechanical stress, and particle cracking.
• Simulation of cracking behavior under varying primary particle size, secondary particle size, and core-shell structures.

Main Results:

• The AP-FPFM accurately captures NCM polycrystalline particle cracking, highlighting the importance of anisotropic volume contraction.
• Demonstrated the influence of particle size and core-shell structures on crack initiation and propagation.
• Identified key parameters and strategies to suppress NCM particle cracking.

Conclusions:

• Anisotropic volume contraction is essential for understanding NCM particle cracking.
• The developed model provides theoretical insights into cracking mechanisms.
• Optimization strategies based on particle design can significantly improve the mechanical stability of NCM cathodes.