Developing supercapacitors with simultaneous superior power and energy density for energy-storage devices remains a challenge. In this work, single-phase NiS₂ microflowers were synthesized through a hydrothermal process coupled with subsequent sulfidation. The obtained NiS₂ microflowers perfectly inherited the flowerlike structure of the precursor, which was composed of nanosheets with firmly integrated nanoparticles. With the benefit of the single-phase crystal structure, suppressed surface oxidation, relatively high apparent conductivity, and unique nano/microstructure, the NiS₂ microflowers presented outstanding electrochemical performance in the LiOH electrolyte. Specifically, the NiS₂ microflowers exhibited high specific capacities of 813 C g^–1 at 1 A g^–1 and 580 C g^–1 at 20 A g^–1 and retained 93% of its initial capacity after 10,000-time cycling test. Moreover, an optimized NiS₂//activated carbon (AC) hybrid supercapacitor fabricated with NiS₂ microflowers as the positive electrode and AC as the negative electrode operated stably at a large voltage window of 1.8 V. It further delivered a considerable energy density of 39.8 W h kg^–1 at 900 W kg^–1. Impressively, the intriguing nano/microstructure further endowed the almost unabated capacitance after continuous cycling of 10,000 times. This study will definitely promote the design and preparation of high-performance nickel-based sulfides for hybrid supercapacitors.

中文翻译：

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单相二硫化镍微花作为混合超级电容器高性能电极的构建

为储能设备开发同时具有优异功率和能量密度的超级电容器仍然是一个挑战。在这项工作中，通过水热过程与随后的硫化反应合成了单相NiS ₂微型花。所获得的NiS ₂微花完美地继承了前体的花状结构，该前体由具有牢固整合的纳米粒子的纳米片组成。受益于单相晶体结构，抑制的表面氧化，相对较高的表观电导率以及独特的纳米/微观结构，NiS ₂微型花在LiOH电解质中表现出出色的电化学性能。具体来说，NiS ₂微型花在1 A g ^–1时表现出813 C g ^–1的高比容，在20 A g ^–1时表现出580 C g ^–1的高比容，经过10,000次循环测试后保留了其初始容量的93％。此外，以NiS ₂微小花为正极，AC为负极制成的优化的NiS ₂活性炭（AC）混合超级电容器可在1.8 V的大电压窗口下稳定运行。它还提供了39.8的可观能量密度W h kg ^–1在900 W kg ^–1时。令人印象深刻的是，经过10,000次连续循环后，迷人的纳米/微结构进一步赋予了几乎未减弱的电容。这项研究肯定会促进混合超级电容器的高性能镍基硫化物的设计和制备。