首页|Mitigating volume expansion of silicon-based anode through interfacial engineering based on intermittent discharge strategy
Mitigating volume expansion of silicon-based anode through interfacial engineering based on intermittent discharge strategy
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Silicon is considered to be one of the most promising anode materials for lithium-ion batteries(LIBs),but its application is limited by the large volume expansion during alloying and dealloying.The constructing of a high-performance solid electrolyte interface(SEI)film on the surface of the anode material is consid-ered to be one of the effective strategies to mitigate volume expansion of silicon-based anode.In this study,an intermittent discharge strategy which helps to improve the utilization efficiency of electrolyte additive of lithium difluorobisoxalate phosphate(LiDFBOP)is proposed to construct a highly conductive and dense SEI film.The results of electrochemical and physical characterization and theoretical calcula-tions show that the intermittent discharge in the voltage range from open circuit voltage(OCV)to 1.8 V facilitates the diffusion of the soluble products,creates the conditions for the repeated direct contact between Si@C anode and LiDFBOP additive,increases the decomposition of LiDFBOP additive,and thus produces a uniform,dense and inorganics-rich(Li2C2O4,LiF and LixPOyFz)SEI film.Subsequently,this SEI film helps to ensure the even intercalation/de-intercalation of Li+in the SEI film and the homogeneous diffusion of Li+inside the Si particles,decreasing the internal stresses and anisotropic phase transitions,maintaining the integrity of Si particles,inhibiting the volume expansion and thus improving the electro-chemical performance of cells.This study not only improves the utilization efficiency of expensive addi-tives through a simply and low-cost method,but also enriches the strategy to improve the electrochemical performance of Si@C anode through interfacial engineering.
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NSTL
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