Ultrafast presodiation of graphene anodes for high-efficiency and high-rate sodium-ion storage

The low initial Coulombic efficiency(ICE)is a significant problem hindering the practical uses of carbon anodes in sodium-ion batteries(SIBs),especially for the carbons with large surface area.Presodiation is an effective way to solve the above problem,but it always needs complicated operations and cannot suppress the unavoidable electrolyte decomposition in the assembled battery.Herein,we develop an ultrafast chemical presodiation method for reduced graphene oxide(rGO)using sodium naphthalene(Na-Nt)dissolved in dimethoxyethane(DME)solvent as a presodiation reagent.The presodiation effectively improves the ICE of rGO to 96.8%and forms an artificial solid electrolyte interphase(SEI)on its surface due to the decomposition of the formed complex between Na+and DME.The formed artificial SEI suppresses the excessive decomposition of electrolytes in the assembled battery,leading to a formation of uniform and inorganic component–rich SEI on rGO surface,which enables a rapid interfacial ion transfer.Therefore,the presodiated rGO showed excellent rate performance with a high capacity of 198.5 mAh g^(-1) at 5 A g^(-1).Moreover,excellent cycle stability indicated by the high capacity retention of 68.4%over 1000 cycles was also achieved,showing the poten-tial to promote the practical uses of high-rate rGO anode in SIBs.