Defect Engineering Boosting High-Performance Graphite Anode for Sodium-Ion Batteries in Ether-Based Electrolytes

Sodium-ion batteries (NIBs) as one of the next-generation energy storage devices are gradually used in energy field and entering lithium-ion batteries (LIBs) market. Graphite with low price exhibits excellent Li+ reversible intercalation properties, which has been widely applied in anodes of LIBs. But it has low capacity for sodium because of its weak chemical bonding with sodium. Here, a defect engineered graphite with low graphitization structure is reported. This graphite demonstrates a defect adsorption and solvated ion intercalation of sodium ions by introducing more active sites and ether electrolytes, effectively improving the storage capacity of sodium. Further experiments and characterization show defects increased after ball milling with surface area increased, and the favorable defects on the interface of graphite are significantly increased. The defect engineered graphite absorbs more sodium-ions and exhibits capacitive characteristics with fast sodiation/desodiation process, leading to an improved capacity storage than the defect-free graphite. Meanwhile, the defect engineered graphite can deliver a capacity of 175 mAh g(-1), and maintain a good capacity retention of 84% at 5 A g(-1) after 6000 cycles. This work discovers a general methodology to obtain defect engineered graphite, which will provide an experimental strategy to achieve large-scale industrialization for low-cost NIBs.