Pseudocapacitors with nickel/cobalt hydroxide-based electrodes show promises energy storage devices, because they are economical and safe, but cycle stability and high current rate capability have not been achieved. We shed light on how magnesium in double-layered hydroxides serves as a supercapacitor electrode in optimal environments. Here we show the high rate capability and long-term stability of layered magnesium–cobalt double hydroxide (L-MCH) electrodes, which is superior to existing electrodes. The pseudocapacitor made with Mg²⁺ and Co²⁺ double hydroxide as active materials, does not have an intricate fabrication process. The L-MCH pseudocapacitor has a specific capacitance comparable to most double hydroxide-based materials and capacity retention greater than 107% over 10,000 cycles, which is in line with commercial devices. Our proposed method also offers a much faster and reliable route for electrode fabrication, which could result in the development of a new generation of supercapacitors, batteries and hybrid devices.

具有基于镍/氢氧化钴的电极的伪电容器显示出前景光明的能量存储设备，因为它们既经济又安全，但尚未实现循环稳定性和高电流速率能力。我们阐明了双层氢氧化物中的镁如何在最佳环境中充当超级电容器电极。在这里，我们展示了层状镁钴双氢氧化物（L-MCH）电极的高倍率性能和长期稳定性，它优于现有电极。由Mg ²⁺和Co ²⁺制成的伪电容器双氢氧化物作为活性材料，没有复杂的制造过程。L-MCH伪电容器的比电容可与大多数双氢氧化物基材料相比，并且在10,000次循环中的容量保持率大于107％，这与商用设备一致。我们提出的方法还为电极制造提供了一条更快，更可靠的途径，这可能会导致新一代超级电容器，电池和混合设备的开发。