Effect of Mechanical Pre-Lithiation on Electrochemical Performance of Silicon Negative Electrode for Lithium-Ion Batteries

The effect of pre-lithiation on the electrochemical performance of Si negative electrodes for lithium-ion batteries was studied. A pre-volume-expansion of Si induced by the pre-lithiation is expected to decrease the relative change in volume of Si during charge-discharge reactions. Suppression of change in volume of Si should improve the cycle performance, the Coulombic efficiency, and so on. When the mechanically pre-doped Li was extracted from Li-Si alloy during the first cycle, an alloy electrode exhibited the poor cycle performance just like a Si-alone electrode. On the other hand, the Li 1.00 Si electrode exhibited the improved cycle performance and higher Coulombic efficiency under the discharge cut-off potential of 0.7 and 0.5 V, respectively. The electrode also showed 1.5 times longer cycle life compared to the Si-alone electrode when the charge capacity and the cut-off potential were limited. These results demonstrated that the appropriate mechanical pre-lithiation helps to improve the poor electrochemical performance of the Si negative electrodes.