Lithium dextran sulfate as dynamic and sustainable coating to stabilize lithium deposition

Lithium metal batteries (LMBs) are attractive because of ultra-high energy density, but the critical problem of lithium dendrites hinders their commercialization. Intensive researches have been devoted to homogenizing the electron distribution of the current collectors to prevent the lithium dendrite. In this work, a renewable lithium dextran sulfate (LDS) binder that can reversibly, dynamically, and strongly bind to the Cu current collectors as well as metallic Li through the -O-SO3– functional group, and has the special characteristic of single-ion-conducting is proposed to regulate homogeneous Li-ion diffusion, stabilize the electrode interface, and considerably decrease the surface stress, thus guide uniform lithium deposition and propagation, endowing the lithium-free LMBs with outstanding areal capacity and cycling stability. The full cells employing the LDS coated Cu foil as Li-free anode and 4.6 V LiCoO2 (LCO) as cathode exhibit an initial capacity of 189 mAh/g with a Coulombic efficiency (CE) of 97%. And the CE increases to more than 99.7% after 20 cycles. The reversible capacity retention rate was more than 72.1% after 100 cycles. This simple strategy of ion distribution homogenization by dynamic binder coating is inspiring to tackle the long-standing problem of metal dendrites for commercial feasibility of anode-free batteries.