Mixed-valence is an effective way to achieve high electrochemical performance of anodes for supercapacitor. However, inordinate mixed valence with more structural defects leads to structural instability. The development of mixed valence electrodes that can maintain a stable structure during the defect formation process is the key to resolving this problem. Cu_2-xSe with mixed-valence is a potential candidate, the stable monoclinic structure of Cu₂Se can be transformed into another stable cubic structure (x > 0.15). Herein, Cu_1.85Se anode with mixed valence reveals the ultrahigh specific capacity of 247.8 mA·h/g at 2 A/g. Furthermore, the introduction of multi-walled carbon nanotubes (MWCNTs) into Cu_1.85Se further improves the specific capacity (435 mA·h/g at 2 A/g). XRD shows that the introduction of MWCNTs can improve the reversibility via chemical interactions and accelerate the electron transfer in the Cu_1.85Se/MWCNTs. Notably, the assembled symmetric supercapacitor (SC) device expresses a high energy density of 41.4 W·h/kg, and the capacity remains 83% even after 8000 charge/discharge cycles. This research demonstrates the great potential of developing high specific capacity anode materials for superior performance supercapacitor.

混合价是实现超级电容器阳极高电化学性能的有效途径。然而，过多的混合价和更多的结构缺陷会导致结构不稳定。开发能够在缺陷形成过程中保持稳定结构的混合价电极是解决这一问题的关键。具有混合价的Cu _{2- x Se是一个潜在的候选者，Cu 2} Se稳定的单斜结构可以转化为另一种稳定的立方结构（x  > 0.15）。在此，具有混合价态的 Cu _1.85 Se 负极在 2 A/g 时显示出 247.8 mA·h/g 的超高比容量。此外，将多壁碳纳米管 (MWCNT) 引入 Cu _1.85Se 进一步提高了比容量（在 2 A/g 时为 435 mA·h/g）。XRD 表明，MWCNT 的引入可以通过化学相互作用提高可逆性，并加速 Cu _1.85 Se/MWCNT中的电子转移。值得注意的是，组装的对称超级电容器（SC）装置表现出41.4 W·h/kg的高能量密度，即使在8000次充放电循环后容量仍保持83%。这项研究证明了开发用于高性能超级电容器的高比容量阳极材料的巨大潜力。