A Low‐Cost and Recyclable Mg/SOCl2 Primary Battery Via Synergistic Solvation and Kinetics Regulation

Abstract Lithium/thionyl chloride (Li/SOCl 2 ) primary batteries are appealing power solutions because of their remarkable electrochemical performances. However, their mass applications are hindered by the challenges in sustainability, cost and safety concerns owing to the employed Li chemistry. Here, magnesium (Mg) chemistry is shown as a promising alternative through synergistic optimization of electrolyte solvation and electrode reaction kinetics. The first Mg/SOCl 2 primary battery yields surprisingly high specific capacities up to ≈14 000 mAh g −1 at a decent discharge voltage of ≈1.67 V, which outperforms the state‐of‐the‐art Mg‐based primary batteries. In addition, it retains almost 100% of the original capacity after 20‐day reservation. The impressive battery performances are originated from the stabilized MgCl 2 formation on high‐surface‐area carbon cathode and suppressed Mg anode corrosion via the Mg‐induced solvation effect. Mg/SOCl 2 primary batteries are promising candidates for low‐cost and recyclable power supplies, and they thus open new avenues for the development of sustainable battery chemistries.