Exceeding 6500 cycles for LiFePO4/Li metal batteries through understanding pulsed charging protocols

Improving the performance of Li metal anodes is of key importance for the next generation high energy-density batteries. Here, we study an easily implementable strategy for prolonging the cycle stability of Li metal anodes that is based on the application of pulsed charging protocols. Introducing short periods of relaxation without current flow allows the concentration of Li+ ions to be replenished in front of the electrode surface promoting a uniform and efficient plating of Li metal. We demonstrate that the cycle life of LiFePO4/Li metal batteries is prolonged from 700 to more than 6500 cycles at high charge-rates. In contrast to the assumed failure due to Li dendrite formation, we show that the proposed potential pulse protocols mitigate the growth of a porous film within the Li metal electrode which appears to be responsible for the battery failure.