A cation-anion synergetic additive achieving long-term stability of lithium metal anode

Lithium metal anode (LMA) has been regarded as the “Holy grail” among next-generation anode materials, which are severely enslaved to its poor cycling stability. Many problems such as Li dendrites and dead Li are involved in the cycling process, thus a protection strategy with a single function is difficult to achieve long-term stability of LMA. Herein, we developed a cation-anion synergetic additive, cesium triiodide (CsI3), to inhibit Li dendrite growth and eliminate dead Li. The addition of Cs+ could play a role in electrostatic shielding to homogenize the deposition progress of Li+, and the further introduction of I3− could react with the inactive Li2O on the surface of the Li to revitalize dead Li. The CsI3-added carbonate or ether electrolyte exhibited excellent cycling stability in a series of electrochemical performance tests, such as the Li-Cu half cell (over 600 cycles), Li-LiFePO4 (LFP, 11.5 mg cm−2, 50 μm Li, 1 μL mg−1 electrolyte) full cells (82% retention over 450 cycles), and Cu-LFP anode-free cells (80% retention over 110 cycles).