Mechanistic understanding of intergranular cracking in NCM cathode material: mesoscale simulation with...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Modeling

Background:

• Intergranular cracking in secondary particles of layered oxide cathodes is a primary cause of mechanical degradation in lithium-ion batteries.
• The precise mechanistic origins of this cracking, particularly concerning mechanical properties, remain poorly understood.

Purpose of the Study:

• To investigate the mechanistic origin of intergranular cracking in layered oxide cathode materials.
• To understand the relationship between mechanical properties, particle adhesion, and structural integrity during battery cycling.

Main Methods:

• Mesoscale simulation combining shifted-force Lennard-Jones potential and granular Hertzian models to construct secondary particle microstructures.
• Optimization of model parameters using nano-indentation and uniaxial tensile test data.
• Analysis of adhesion effects on deformation modes and structural changes during electrochemical cycling.

Main Results:

• Increased particle adhesion significantly strengthens the material under tension but also increases brittleness.
• Localized compression (nano-indentation) response is less sensitive to adhesion changes compared to tensile response.
• Enhanced particle adhesion was found to effectively inhibit the propagation of intergranular cracking during simulated electrochemical cycling.

Conclusions:

• Particle adhesion is a critical factor influencing the mechanical stability of layered oxide cathodes.
• Tailoring inter-particle adhesion offers a viable strategy to mitigate mechanical degradation and improve the lifespan of lithium-ion batteries.