High‐Energy Sodium Ion Batteries Enabled by Switching Sodiophobic Graphite into Sodiophilic and High‐Capacity Anodes
Linlong Lyu, Yichun Zheng, Yingkai Hua, Jien Li, Yuyang Yi, Yang Sun, Zheng‐Long Xu
Abstract
Abstract Owing to the crustal abundance of sodium element, sodium ion batteries (SIBs) are considered a promising complementary to lithium‐ion battery for stationary energy storage applications. The cointercalation chemistry enables the use of cost‐effective graphite as anodes, whereas the low capacity (<130 mAh g −1 ) and high redox potential (>0.6 V vs. Na/Na + ) of graphite significantly limit the energy density of SIBs. Herein, we induce the high‐capacity Na metal into sodiophilic ternary graphite intercalation compounds ( t ‐GICs) via co‐intercalation and deposition reactions, thereby achieving Na/ t ‐GIC anodes with high capacities and low working voltage (0.18 V). The new anodes exhibit high coulombic efficiencies of above 99.7 % over 550 cycles and a high‐rate capacity of 588.4 mAh g −1 at 6 C (10 min per charge). When it is paired with Na 3 V 2 (PO 4 ) 2 F 3 (NVPF) cathodes, the SIBs demonstrate a high energy density of 259 Wh kg −1 both electrodes surpassing that of commercial LiFePO 4 //graphite batteries. The outstanding anode performance is attributed to the tailored sodiophilicity of graphite through manipulating the ether solvents and the in situ generated space among t ‐GIC flakes to stably accommodate Na metal. Our findings for stable Na plating/striping on sodiophilic graphite materials provide an effective approach for developing advanced SIBs.