| 초록 |
We reported the Cu2P2O7/carbon-nanotube nano-composite (Nano-C-Cu2P2O7) as a high energy density cathode material for sodium-ion batteries (NIBs). Cu2P2O7 is the material which undergoes the conversion reaction during charge/discharge process, and it showed higher average operation voltage than other conversion-based cathode for NIBs, because it was designed to maximize the inductive effect via poly-anion. In electrochemical properties, Nano-C-Cu2P2O7 showed a capacity of 355 mAh g-1 at C/30, which is consistent with theoretical capacity of Cu2P2O7 and maintained a high capacity of 223 mAh g-1 at 5C. Furthermore, nano-C-Cu2P2O7 exhibited capacity retention of over 75 % for the initial capacity for 300 cycles at 1C. Cu2P2O7 undergoes the conversion reaction mechanism of ＜Cu2P2O7 + 4Na+ + 4e− → 2Cu + Na4P2O7＞ during charge/discharge, and It was identified using operando/ex situ XRD, ToF-SIMS, TEM, XANES and EXAFS analysis. |
