Graphite is the dominant anode material for lithium-ion batteries;however,it still suffers from Li-plating when charging fast or at low temperature,and Liplating is associated with performance fading and safety concer...Graphite is the dominant anode material for lithium-ion batteries;however,it still suffers from Li-plating when charging fast or at low temperature,and Liplating is associated with performance fading and safety concerns.Herein,we clarify the mechanism of lithium evolution from graphite particles by overlithiation cycle test,in-situ XRD,and titration gas chromatography.We observe that the graphite intercalation compounds(GICs,LiC_(12) and LiC_(6)e.g.)gradually become inactive and wrapped by dead lithium or side reaction sediments,while the rate of this degradation will be accelerated as the overpotential of Liplating is decreased after initial Li metal nucleation.This understanding is contradictory to the popular one that the degradation of graphite anode after Li plating is mainly caused by the inferior SEI and dead Li induced hindering of Li-ion intercalation.The isolation of lithiated graphite particles leading to the fast vanishing of Li insertion/deintercalation process in graphite anodes.We further study the insertion/deintercalation vanishing process at low temperature and high rates,respectively.This work provides a insight on graphite anode degradation induced by Li-plating,and the new understanding can be used to guide the design of advanced materials and electrodes to avoid Li-plating and achieve extreme fast while safe charging.展开更多
基金National Natural Science Foundation of China(No.21875284,22075320,and 52073161)the Ministry of Science and Technology of China(No.2019YFE0100200 and 2019YFA0705703)the Tsinghua University Initiative Scientific Research Program(No.2019THFS0104)。
文摘Graphite is the dominant anode material for lithium-ion batteries;however,it still suffers from Li-plating when charging fast or at low temperature,and Liplating is associated with performance fading and safety concerns.Herein,we clarify the mechanism of lithium evolution from graphite particles by overlithiation cycle test,in-situ XRD,and titration gas chromatography.We observe that the graphite intercalation compounds(GICs,LiC_(12) and LiC_(6)e.g.)gradually become inactive and wrapped by dead lithium or side reaction sediments,while the rate of this degradation will be accelerated as the overpotential of Liplating is decreased after initial Li metal nucleation.This understanding is contradictory to the popular one that the degradation of graphite anode after Li plating is mainly caused by the inferior SEI and dead Li induced hindering of Li-ion intercalation.The isolation of lithiated graphite particles leading to the fast vanishing of Li insertion/deintercalation process in graphite anodes.We further study the insertion/deintercalation vanishing process at low temperature and high rates,respectively.This work provides a insight on graphite anode degradation induced by Li-plating,and the new understanding can be used to guide the design of advanced materials and electrodes to avoid Li-plating and achieve extreme fast while safe charging.
