The low energy density of asymmetric supercapacitors (ASCs) is mainly attributable to the low capacitance of the negative electrode; consequently, developing negative electrodes with high capacitance is crucial to boosting the energy density of ASCs. Vanadium nitride (VN), with excellent theoretical capacitance, is an ideal negative electrode material, but its low conductivity and poor electrochemical stability limit its application in energy storage. Herein, we design a high-performance monolithic negative electrode of ASCs that consists of well-defined porous VN nanosheets stacked with small nanoparticles decorated on a conductive substrate of ultrafine cobalt-encapsulated nitrogen-doped carbon nanotubes on carbon cloth (VN NS/Co@NCNTs/CC). Because the Co@NCNTs/CC substrate can enhance conductivity and facilitate the dispersion of active species and the exposure of more reaction sites, the newly developed porous VN NS/Co@NCNTs/CC negative electrode exhibits a high capacitance of 1016 mF cm⁻² (782.3 F g⁻¹) at 2 mA cm⁻² and a superior cycle stability (110% capacitance retention after 11,000 cycles). To construct the ASC, a positive electrode of manganese dioxide (MnO₂) nanoneedles grown on Co@NCNTs/CC (MnO₂ NN/Co@NCNTs/CC) was also built using a similar preparation method. Benefiting from the wide operating voltage and high capacitance of the negative and positive electrodes, the assembled ASC can operate stably at a high voltage of 2 V. More importantly, the ASC can reach an energy density of 29.9 μWh cm⁻² (23.9 Wh kg⁻¹) and a capacitance retention of 94.3 % after 20,000 cycles, outperforming most of the reported aqueous ASC devices. This study provides a feasible way to reasonably design ASC electrodes with superior electrochemical performance.

非对称超级电容器（ASCs）的低能量密度主要归因于负极的低电容；因此，开发具有高电容的负电极对于提高 ASC 的能量密度至关重要。氮化钒（VN）具有优异的理论电容，是一种理想的负极材料，但其低电导率和较差的电化学稳定性限制了其在储能领域的应用。在此，我们设计了一种高性能的 ASC 单片负电极，它由定义明确的多孔 VN 纳米片组成，这些纳米片堆叠有小纳米粒子，装饰在碳布上的超细钴包封氮掺杂碳纳米管导电基板上 (VN NS/Co@ NCNT/CC)。⁻² (782.3 F g ⁻¹ ) 在 2 mA cm ⁻²和优异的循环稳定性（11,000 次循环后 110% 的电容保持率）。为了构建 ASC，还使用类似的制备方法构建了生长在 Co@NCNTs/CC (MnO ₂ NN/Co@NCNTs/CC) 上的二氧化锰 (MnO _{2 ) 纳米针正极。}得益于正负电极的宽工作电压和高电容，组装的ASC可以在2 V的高电压下稳定工作。更重要的是，ASC可以达到29.9 μWh cm ^-2 (23.9 Wh kg ⁻¹) 和 20,000 次循环后的电容保持率为 94.3%，优于大多数报道的水性 ASC 器件。该研究为合理设计具有优异电化学性能的ASC电极提供了一种可行的方法。