Gradient Elasticity Effects on the Two-Phase Lithiation of LIB Anodes
A coupled gradient chemoelasticity theory is employed to model the two-phase mechanism that occurs during lithiation of silicon nanoparticles used to fabricate next generation Li-ion battery (LIB) anodes. It is shown that the strain gradient length scale is able to predict the propagation of an interface front of nonzero thickness advancing from the lithiated to unlithiated region without necessarily including higher-order concentration gradients of the Li ions. Larger strain gradient coefficients (elastic internal lengths) induce more diffused interfaces and faster lithiation, which affect both internal strain and stress distributions in a similar way. Estimates for the migration velocity of the phase boundary are obtained and a range of values of the strain gradient length scale is shown to simulate the observed experimental results.
The input and discussions with Professor Katerina Aifantis of the University of Florida on the topic of LIBs were very useful and deeply appreciated. The support of the Ministry of Education and Science of Russian Federation under Mega-Grant No.14.Z50.31.0039 is also gratefully acknowledged.
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