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Abstract Partial lithiation strategies for silicon composite electrodes are experimentally investigated in this article. Two types of partial lithiation, i.e. voltage- and capacity-control strategies, are presented. Capacity loss and irreversibility of silicon electrodes are significantly suppressed by either partial lithiation strategy without any complicated modifications or treatments. The capacity of partially lithiated silicon electrodes is even higher than that of fully lithiated one after certain cycles. The images of scanning electron microscope suggest that the mechanical damage generated in partially lithiated electrodes is less than that in fully lithiated one. Furthermore, after dozens of cycles with partial lithiation, capacity decay also slows down in subsequent full charge-discharge cycles. The presented experimental results suggest that the partial lithiation strategy relieves the coupled mechanical-electrochemical degradation and is a promising approach for the long-term use of silicon composite electrodes. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, structural configuration of layered Li-ion battery electrode plates is evaluated by analytically formulating the diffusion induced stress. Both symmetric electrode and asymmetric bilayer electrode are discussed. The thickness ratio and the modulus ratio of current collector to active plate are analytically identified to be the important influence parameters on the stress. Applying a material with smaller elastic modulus for current collector could reduce the peak stresses in both current collector and active plate. Increasing the thickness of current collector would reduce the stress in itself while promote the stress in active plate. Therefore, from mechanical viewpoint on designing an electrode, the material for current collector should be as soft and flexible as possible. And the thickness of current collector should be in an appropriate range. Basically, it should be as small as possible on the precondition that the mechanical strength is satisfied. Finally, effects of three charging conditions, i.e. uniform, galvanostatic, and potentiostatic, on the diffusion induced stress is discussed. It is found the maximum stresses for three cases are linear to the total amount of intercalated lithium ions. Based on the stresses, an optimized charging operation, i.e. first galvanostatic followed by potentiostatic, is suggested. [Copyright &y& Elsevier]