Cotton pad derived 3D lithiophilic carbon host for robust Li metal anode: In-situ generated ionic conductive Li3N protective decoration

Abstract Lithium metal anode is considered as one of the most promising candidates for the next-generation batteries with high specific energy density. However, several thorny problems encompassing uncontrollable Li dendritic growth and wild volume variation during cycling, accompanied by the short lifespan and alarming safety concerns, have hindered the commercial viability of Li metal-based batteries. In this contribution, we designed a Li composite anode fabricated via Li infusion into N, O co-doped and Ag coated 3D carbon host from simple treatments of commercial cotton pads, referred as Ag-NOCP@Li. The incorporation of multi lithiophilic atoms can significantly improve the affinity of 3D carbon host towards Li. More importantly, during molten Li infiltration, the composite anode can in-situ generate Li3N decoration, an excellent Li+ conductor and electron insulator. The first-principles calculations further revealed that the active sites for the Li3N generation most likely are pyrrolic nitrogen sites. The Li3N with favorable mechanical strength and ultra-fast Li+ diffusion rate can effectively boost the kinetics of Li transport and redox, as well as inhibit the dendritic generation. Besides, the Ag-NOCP with hierarchical pores and multi-microchannel within the nanofibers, allows the rapid Li+ diffusion and buffers the volume change over long cycling. Therefore, such Ag-NOCP@Li electrode could maintain a stable cycling for 1400 h at 1.0 mA cm−2/1.0 mAh cm−2. The full cells using Ag-NOCP@Li anode paired with LiFePO4 and LiNi0.5Co0.2Mn0.3O2 cathodes, displayed impressive long-term cyclic stability up to 400 cycles at 0.5 and 1.0 C, respectively. This work paves new way for rational design of 3D lithiophilic host towards durable Li anode.