Pseudocapacitance Induced Uniform Plating/Stripping of Li Metal Anode in Vertical Graphene Nanowalls

Unevenly distributed dendrite growth is usually viewed as a consequence to the diffusion-limited interface instability during electrodeposition, leading to one of the most serious obstacles hindering the application of high-capacity lithium (Li) metal anodes. Herein, a fundamental issue of modifying Li plating behavior using a structure of 3D vertical graphene nanowalls on nickel (Ni) foam (VGN/Ni) is investigated. Such a structure exhibits a significant pseudocapacitive interfacial feature, greatly improving the Li+ ion transfer kinetic through the structure, and exhibiting uniform Li plating/stripping for stable Li metal cycling even at a high depth of discharge of 50%. Based on such a structure, high Coulombic efficiencies approximate to 97% and 99% can be obtained in carbonate and ether electrolyte over long-term cycling. The symmetrical cell based on the VGN/Ni@Li composite anodes can afford a stable cycling of 2000 h with low voltage hysteresis of 30 mV. Full cell system using VGN/Ni@Li composite anode and LiFePO4 cathode is also proved, with high capacity retention of 89.4% at the 1000th cycle. The pseudocapacitance induced benefits, which have not yet been elucidated for Li metal anodes, can conduct to underlying strategy in designing stable Li metal host for high-energy. density batteries.