Potassium-ion-battery (PIB) and sodium-ion-battery (SIB) have been considered as next-generation energy storage devices due to their low-cost and abundant resource. The main challenge lies in the lack of novel electrodes to accommodate the large-size K/Na-ions. Herein, a facile solvothermal method coupled with a polydopamine coating and post-annealing strategy is developed to synthesize unique box-like NiS@C. NiS particles are encapsulated in nitrogen-doped carbon cages via the Ni–N bond, presenting excellent sodium/potassium-ion storage performances. The coexistence of nitrogen doped carbon, as well as the chemical bond between NiS and carbon endows the composite with highly conductive network and fast ionic diffusion channels, exhibiting excellent rate capability. The superior cyclic stability can be attributable to the stronger affinity of N-doped carbon to NiS and discharge products, which has been further demonstrated through first-principles density functional theory (DFT) simulations. NiS@C delivers a high Na-ion-storage capacity of 632 mAh g⁻¹ at 5 A g⁻¹ over 2000 cycles. A stable K-ion storage capacity of 171 mAh g⁻¹ can be retained at 1 A g⁻¹ after 300 cycles. These findings suggest box-like NiS@C is a promising anode candidate for alkali-ion batteries. Present synthetic approach could be extended to other functional electrode materials for energy-storage applications.

钾离子电池（PIB）和钠离子电池（SIB）由于其低成本和丰富的资源而被视为下一代能量存储设备。主要挑战在于缺乏新颖的电极来容纳大尺寸的K / Na离子。在本文中，结合聚多巴胺涂层和后退火策略，开发了一种简便的溶剂热方法，以合成独特的盒状NiS @ C。NiS颗粒通过Ni–N键封装在氮掺杂的碳笼中，具有出色的钠/钾离子存储性能。氮掺杂碳的共存以及NiS和碳之间的化学键使复合材料具有高导电性网络和快速的离子扩散通道，具有出色的速率性能。优异的循环稳定性可归因于氮掺杂碳对NiS和放电产物的较强亲和力，这已通过第一原理密度泛函理论（DFT）模拟得到了进一步证明。NiS @ C可提供632 mAh g的高钠离子存储容量^-1在5 A G ^-1超过2000个循环。300次循环后，可以在1 A g ^-1下保持171 mAh g ^-1的稳定K离子存储容量。这些发现表明，盒状NiS @ C是碱离子电池的有希望的阳极候选材料。当前的合成方法可以扩展到用于能量存储应用的其他功能电极材料。