Mechanical stresses at the cathode-electrolyte interface in lithium-ion batteries

Experimental studies have shown capacity loss and impedance rise on the surfaces of cathode particles during (dis)charging in lithium-ion batteries. However, there are surprisingly few studies focusing on the cathode-electrolyte interface. The current study uses multiphysics finite element models to understand fluid-structure interactions in a half-cell battery system. Effects of C-rate, particle sizes, lithiation, and phase transformation of the cathode at the interface are investigated. Results demonstrate that doubling the particle size results in larger available lithium intercalation areas, giving rise to increased tension 1.40 times and compression 1.82 times at the interface. Moreover, higher C-rate with high lithium-ion concentration gradient results in higher mechanical stresses at the interface. These coupling factors are strongly related to the experimentally observed battery degradation. Our simulations demonstrate that both electrode and electrolyte have pronounced effects when investigating mechanical stresses at the electrode-electrolyte interface.