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Stress-modulated driving force for lithiation reaction in hollow nano-anodes

Zheng Jia (University of Maryland), Teng Li (University of Maryland)

Lithium ion batteries: When Chemistry meets Mechanics

Tue 9:00 - 10:30

Salomon 003

In lithium-ion battery, lithiation of crystalline silicon proceeds by the movement of an atomically-sharp reaction front which separates the pristine crystalline silicon phase and the fully-lithiated amorphous Li_3.75 Si phase. The velocity of the reaction front is limited by the reaction rate at the front rather than by the diffusivity of lithium in the amorphous lithiated phase. Recent experimental evidence on nano-particle and nano-wire silicon anodes showed an initial rapid velocity of reaction front at the initial stage of lithiation, followed by an apparent slowing or even halting of the reaction front. This intriguing phenomenon is attributed to the lithiation-induced mechanical stresses across the reaction front which is believed to play an important role in the kinetics of reaction at the front. In previous studies, electro-chemo-mechanical driving force for the movement of lithiation front has been identified and effect of mechanical stress on reaction rate in solid spherical and cylindrical anodes has been investigated. Here, through theoretical formulation and finite element analysis, we presented a comprehensive study on lithiation-induced stress distribution and its contribution on driving force of lithiation in hollow nano-sphere or nano-wire anodes with different mechanical constraint at the inner surface. Our results reveal hollow nano-sphere (nano-wire) anodes can be more efficiently lithiated than their solid counterparts and thus shed light on the optimal design of high performance anodes of lithium-ion battery.