The use of pseudocapacitive electrode materials can enable devices to store more energy than electrical double-layer capacitors (EDLCs). However, only a few pseudocapacitive materials can maintain excellent performance at low temperatures, which limits their application in harsh climate conditions. Here we demonstrate that a pseudocapacitor with two-dimensional transition metal carbide (MXene) electrode can exhibit excellent low-temperature performance like EDLC. The MXene electrodes contain electrolyte between 2D sheets, and the electrolyte ions can unimpededly reach redox-active sites and interact with surface oxygen groups rapidly, even at low temperatures. With a combination of 40 wt.% sulfuric acid solution as the electrolyte, the working temperature of the MXene electrode extends to -60 °C. The electrode exhibits temperature-insensitive performance at a low scan rate, and the capacity of MXene (88 mAh g⁻¹ at 5 mV s⁻¹) stays almost constant when the temperature decreases from 20 to -50 °C. Moreover, at -50 °C, MXene electrodes show a high capacity retention of > 75% at 100 mV s⁻¹, indicating good low-temperature rate performance. Interestingly, a broad working potential window of 1.5 V is achieved at -60 °C. Such an excellent low-temperature performance demonstrates that MXene is a promising electrode candidate for low-temperature pseudocapacitive energy storage applications.

伪电容电极材料的使用可使设备比双电层电容器（EDLC）存储更多的能量。但是，只有几种假电容材料可以在低温下保持出色的性能，这限制了它们在恶劣气候条件下的应用。在这里，我们证明具有二维过渡金属碳化物（MXene）电极的伪电容器可以表现出出色的低温性能，如EDLC。MXene电极在2D薄片之间包含电解质，即使在低温下，电解质离子也可以无阻地到达氧化还原活性位点并迅速与表面氧基团相互作用。使用40％（重量）的硫酸溶液作为电解质，MXene电极的工作温度可扩展至-60°C。当温度从20降低到-50°C时，^-1在5 mV s ^-1）几乎保持恒定。此外，在-50°C下，MXene电极在100 mV s ^-1下显示出> 75％的高容量保持率，表明良好的低温速率性能。有趣的是，在-60°C时可获得1.5 V的宽工作电势窗口。如此优异的低温性能证明MXene是低温伪电容式储能应用的有希望的电极候选者。