Enhanced Capacity of Lithium Secondary Batteries Using a Li-Powder Anode

초록

Li-graphite and Li-O-2 cells were investigated to increase their capacity, similar to that reported for other Li-powder anode-based cells such as Li-V2O5, Li-LiV3O8, and Li-sulfur batteries. When a Li-powder anode was used instead of a Li-foil anode in a Li-graphite cell, there was an increase of approximately 8% in the discharge capacity at a 0.1C rate. In a Li-O-2 cell, the Li-powder anode showed an enhancement capacity of approximately 20%, as well as improved cycle performance and lower discharge/charge overpotential compared to the Li-foil anode. To explain the enhanced capacity obtained using the Li-powder anode, the exchange current density and Li+ concentration gradient at the cathode surface were calculated using electrochemical methods such as linear sweep voltammetry and cyclic voltammetry. The Li powder caused an increase in the exchange current density, which enhanced the Li-ion concentration gradient at the surface of the cathode. Therefore, the increase in cell capacity can be attributed to an enhanced Li+ flux due to the higher Li+ concentration gradient at the surface of the cathode. X-ray photoelectron spectroscopy and scanning electron microscopy results indicate that the Li-powder anode not only suppressed side reactions in the electrolyte but also promoted uniform lithium peroxide deposition on the cathode of the Li-O-2 cell.

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