Self-sacrificing lithium source with high electrochemical activity and water oxygen stability and its application in Si-C//S battery

Abstract

Most lithium compensation materials are sensitive to water and oxygen and their electrochemical activity is low. In this study, a high electrochemical activity and water oxygen-stable di-lithium squamate (Li2C4O4) were developed as lithium compensation agent and lithium source . The catalytic effect of carbon defects on Li2C4O4 decomposition was found through ex situ measurement and density functional theory calculation (DFT). Based on this result, the decomposition efficiency of this agent was increased to 2.5 times through the selection of the conductor. Because of the nearly 100% decomposition efficiency, this lithium compensation agent can be also used as a lithium source for the lithium-free battery system. In this study, this agent was used in a lithium-metal-free Si–C//S/pPAN battery system, without the constraints of the lithium-metal anode, the assembly environmental demand for this battery can be significantly reduced. Furthermore, we found that the CO2 produced in the decomposition process can modify the solid electrolyte interphase (SEI) membrane, which can significantly improve the cycle performance. We obtained a long cycle metal-free Si–C//S/pPAN battery with a specific capacity of 1200 mAh g−1 at a 1C current density. We also assembled the soft-pack battery, and obtained a Si–C//S/pPAN soft-pack battery with an energy density of 340.3 Wh kg−1, and more than 96.9% of the capacity remained after 300 cycles.