A periodic reactivation strategy with redox mediator towards dead Lithium-free Lithium metal batteries

Dead lithium limits the application of lithium metal batteries, and reactivating it via redox mediators has been proven effective. However, the insufficient reaction time of redox mediators limits their reactivation efficiency. Here, a novel periodic reactivation strategy using 1,4-di-tert-butyl-2,5-dimethoxybenzene is proposed. The reactivation process is controlled by reducing the charging/discharging rate and is initiated periodically during cycling. DDB is then oxidized to DDB + at 3.95 V, shuttles to the anode, and reacts with dead lithium to re-dissolve it as Li + , accomplishing periodical in situ reactivation. This strategy enables an order-of-magnitude reduction in dead lithium, effective cycling capacity recovery, and excellent long-term cycling performance of LiFePO₄-Li cells. • A rate-controlled periodic reactivation strategy usingDDB is proposed to mitigate dead lithium in batteries. • In the low-rate cycling, DDB oxidizes to DDB + and shuttles to anode to react metallic dead lithium into active Li + . • The strategy achieves an order-of-magnitude reduction in dead lithium mass, quantified via titration gas chromatography. • LiFePO₄-Li cells exhibit an average capacity recovery of 14.33 mAh g −1 following periodic reactivation.