Phosphorus-based anode is a promising anode for sodium-ion batteries(SIBs)due to its high specific capacity,however,suffers from poor electronic conductivity and unfavorable electrochemical reversibility.Incorporating...Phosphorus-based anode is a promising anode for sodium-ion batteries(SIBs)due to its high specific capacity,however,suffers from poor electronic conductivity and unfavorable electrochemical reversibility.Incorporating metals such as copper(Cu)into phosphorus has been demonstrated to not only improve the electronic conductivity but also accommodate the volume change during cycling,yet the underline sodiation mechanism is not clear.Herein,take a copper phosphide and reduced graphene oxide(CuP_(2)/C)composite as an example,which delivers a high reversible capacity of>900 mAh/g.Interestingly,it is revealed that the native oxidation PO_(x)components of the CuP_(2)/C composite show higher electrochemical reversibility than the bulk Cu P_(2),based on a quantitative analysis of high-resolution solid-state^(31)P NMR,ex-situ XPS and synchrotron X-ray diffraction characterization techniques.The sodiation products Na_(3)PO_(4) and Na_(4)P_(2)O_(7) derived from PO_(x) could react with Na-P alloys and regenerate to PO_(x) during charge process,which probably accounts for the high reversible capacity of the Cu P_(2)/C anode.The findings also illustrate that the phosphorus transforms into nanocrystalline Na_(3)P and Na_(x)P alloys,which laterally shows crystallization-amorphization evolution process during cycling.展开更多
基金financially supported by National Nature Science Foundation of China(Nos.21805278,22272175 and 22209075)the Fujian Science and Technology Planning Projects of China(Nos.2022T3067 and 2023H0045)+1 种基金the Self-deployment Project Research Programs of Haixi Institutes,Chinese Academy of Sciences(No.CXZX-2022-JQ12)the Self-deployment project of XIREM(No.2023GG02)。
文摘Phosphorus-based anode is a promising anode for sodium-ion batteries(SIBs)due to its high specific capacity,however,suffers from poor electronic conductivity and unfavorable electrochemical reversibility.Incorporating metals such as copper(Cu)into phosphorus has been demonstrated to not only improve the electronic conductivity but also accommodate the volume change during cycling,yet the underline sodiation mechanism is not clear.Herein,take a copper phosphide and reduced graphene oxide(CuP_(2)/C)composite as an example,which delivers a high reversible capacity of>900 mAh/g.Interestingly,it is revealed that the native oxidation PO_(x)components of the CuP_(2)/C composite show higher electrochemical reversibility than the bulk Cu P_(2),based on a quantitative analysis of high-resolution solid-state^(31)P NMR,ex-situ XPS and synchrotron X-ray diffraction characterization techniques.The sodiation products Na_(3)PO_(4) and Na_(4)P_(2)O_(7) derived from PO_(x) could react with Na-P alloys and regenerate to PO_(x) during charge process,which probably accounts for the high reversible capacity of the Cu P_(2)/C anode.The findings also illustrate that the phosphorus transforms into nanocrystalline Na_(3)P and Na_(x)P alloys,which laterally shows crystallization-amorphization evolution process during cycling.
