Seed-free selective deposition of lithium into fluorine/oxygen co-doped interconnected stacked hollow carbon spheres for stable lithium metal anode

Abstract Porous carbon derived from biomass is a potential host for practical lithium (Li) metal anode. However, natural lithiophobicity and heterogeneity of these materials cause uncontrollable Li dendrites and unsatisfied electrochemical performance, frustrating commercialization process of Li metal anode. Herein, we designed a scalable lithiophilic interconnected stacked hollow carbon spheres (ISHCP) derived from starch through one-step fluorine/oxygen co-doping (FO-ISHCP). Interestingly, not only is SiO2 template removed from ISHCP@SiO2 during the hydrofluoric acid (HF) etching process, but also the ISHCP achieves one-step fluorine/oxygen functionalization simultaneously. Impressively, density functional theory (DFT) calculations demonstrate that FO-ISHCP enriched with –F and –O groups exhibits stronger binding energy with Li atom in relation to ISHCP, facilitating uniform Li nucleation and in situ constructing a LiF-rich solid electrolyte interface (SEI) layer. Consequently, rapid transfer of Li+ and selective deposition of Li metal into FO-ISHCP can be very easy to obtain. Benefiting from these ingenious designs, the cycling reversibility of FO-ISHCP-based Li metal anode is improved remarkably. An average Coulombic efficiency (CE) of 98.5% with about 400 cycles at 1 mA/cm2 and over 1400 h of stable Li plating-stripping with a low overpotential of 12.1 mV were successfully operated. Moreover, full cells coupled with a LiFePO4 cathode and FO-ISHCP-Li anode deliver a reversible discharge capacity of 113 mAh/g for more than 200 cycles at 2 C and a dramatical rate capability, indicating its potential for actual applications in future.