Chemically Presodiated Hard Carbon Anodes with Enhanced Initial Coulombic Efficiencies for High-Energy Sodium Ion Batteries
Mengchuang Liu, Junyao Zhang, Shuhan Guo, Bo Wang, Yifei Shen, Xinping Ai, Hanxi Yang, Jiangfeng Qian
Abstract
Hard carbon (HC) is an attractive anode material for low-cost and high-energy density sodium-ion batteries (SIBs); however, its low initial Coulombic efficiency (ICE) limits its practical battery application. To overcome this problem, we reported a facile strategy to compensate the irreversible capacity loss of HC anodes simply by a chemical presodiation reaction of the HC electrode with a sodiation reagent (sodium biphenyl, Na-Bp). Benefiting from the strong sodiation ability of Na-Bp, HC anodes can be presodiated rapidly in a very short time and the presodiated HC (NaxHC) is found to have a desirable ICE of 100%. When coupled with the Na3V2(PO4)3 cathode to build a SIB full cell, the NaxHC||Na3V2(PO4)3 cell exhibits a high ICE of ∼95.0% and an elevated energy density of 218 W h kg–1, which are far superior to those of the control cell using a pristine HC anode (50% ICE and 120 W h kg–1, respectively), suggesting great advantages brought about by the chemical presodiation process. More importantly, this presodiation reaction is very mild and highly efficient and can be widely extended to a variety of Na-storage materials, offering a new route to develop high-performance Na-storage materials for practical battery applications.