Electron regulation enabled selective lithium deposition for stable anodes of lithium-metal batteries†
Lithium metal has been regarded as a promising anode material for next-generation high energy rechargeable batteries due to its high theoretical specific capacity, low density and lowest electrochemical potential. However, lithium metal anodes undergo Li dendrite formation during the cycling process, which may cause safety hazards. To address this issue, we herein report a novel electron regulation strategy via a solid electrolyte interphase (SEI) wrapped tubular carbon array (TCA) for design of stable lithium metal anodes. The pre-formed SEI layer at the outer surface of the TCA creates higher impedance than the inner surface; this results in selective electron transport along the tubular carbon to/from the current collector, rather than through the SEI layer, so that lithiation occurs inside the ordered tubular carbon, thus minimizing or preventing dendrite growth. With this strategy, a Li metal anode with high coulombic efficiency (98% during 200 cycles) and stable cycling performance (>150 h at 1 mA cm−2 with 2 mA h cm−2) is obtained. With this anode, a lithium–sulfur battery exhibits high coulombic efficiency (∼98%) and good cycling stability (942 mA h g−1 at 0.1C after 100 cycles). Our work provides a simple but effective strategy to design stable Li metal anodes.