Appropriate material is the key to improve the energy and power density of sodium ion batteries. Herein, monoclinic Cu₂Se is acquired by a facile one-pot solid method using Cu foil and Se power as the raw materials without use of expensive reagents and sophisticated instruments. Cu₂Se exhibits preeminent cycling and rate properties. Concretely, Cu₂Se represents reversible capacity of 264 and 241 mAh g⁻¹ at 0.1 and 10 A g⁻¹, as well as high capacity retention of ≈100% over 1000 cycles at 1 A g⁻¹. When Cu₂Se is applied as anode to assemble full battery with Na₃V₂(PO₄)₂F₃@rGO, this battery exhibits a largest energy density of 97 Wh kg⁻¹ (with a power density of 117 W kg⁻¹) and a biggest power density of 1180 W kg⁻¹ (with energy density of 59 Wh kg⁻¹) based on the gross mass of cathode and anode active materials. A combination of ex-situ X-ray diffraction, transition electron microscopy tests and first-principle calculations demonstrate a reversible transformation between Cu₂Se and Cu exists in the discharge-charge process. Stable solid-electrolyte interface film, highly infiltrative electrode and capacitive Na ⁺ storage behaviours are in favor of the excellent property. The preeminent electrochemical performance indicates that Cu₂Se is a highly desirable anode material for high-performance sodium ion batteries.

合适的材料是提高钠离子电池能量和功率密度的关键。在此，单斜晶Cu ₂ Se是通过使用铜箔和Se粉作为原料的简便的一锅法固体法获得的，而无需使用昂贵的试剂和复杂的仪器。Cu ₂ Se表现出卓越的循环和速率特性。具体地，Cu ₂ Se代表在0.1和10 A g ^-1时的264和241 mAh g ^-1的可逆容量，以及在1 A g ^-1的1000次循环中的≈100％的高容量保持率。当将Cu ₂ Se用作阳极以与Na ₃ V ₂（PO ₄）₂组装完整电池时˚F ₃ @rGO，这种电池表现出97瓦时千克的最大能量密度^-1（具有117千克w ^的功率密度^-1）和1180W¯¯kg的最大功率密度^-1（具有59瓦千克的能量密度^{- 1}）基于正极和负极活性物质的总质量。异位X射线衍射，过渡电子显微镜测试和第一性原理计算的结合表明，在放电过程中，Cu ₂ Se和Cu之间存在可逆转变。稳定的固体电解质界面膜，高渗透性电极和电容性Na  ⁺ 存储行为有利于优良的性能。出色的电化学性能表明，Cu ₂ Se是用于高性能钠离子电池的非常理想的负极材料。