Ni_xS_y in various crystal phases (NiS, NiS₂, and Ni₃S₄) was synthesized on thermally reduced graphene oxide (TRGO) by a one-step hydrothermal process. Microstructures and morphologies of as-prepared Ni_xS_y–TRGO composites were characterized. Ni_xS_y was formed as microflowers with average size of 1.1–2.3 µm, which grew homogeneously on the curved TRGO nanosheets. Electrochemical performance of Ni_xS_y–TRGO was revealed with high specific capacitance of 1602.2 F g⁻¹ at 1 A g⁻¹ and favorable cycling retention of 90.81% after 3000 cycles at 5 A g⁻¹. An asymmetric supercapacitor device based on Ni_xS_y–TRGO||TRGO exhibited a superior energy density of 39.78 Wh kg⁻¹ at the power density of 0.75 kW kg⁻¹ with an cycling stability of 91.2% capacitance retention after 3000 cycles. Thus, the as-prepared Ni_xS_y–TRGO could be an advanced supercapacitor electrode material.

通过一步还原水热法在热还原氧化石墨烯（TRGO）上合成了各种晶相（NiS，NiS ₂和Ni ₃ S ₄）的Ni _x S _y。表征了制备的Ni _x S _y -TRGO复合材料的微观结构和形貌。Ni _x S _y形成为微花，平均大小为1.1–2.3 µm，在弯曲的TRGO纳米片上均匀生长。Ni _x S _y –TRGO的电化学性能显示出在1 A g ^-1下具有1602.2 F g ^-1的高比电容在5 A g ^-1下经过3000次循环后，循环保留率达到90.81％。基于Ni _x S _y -TRGO || TRGO的非对称超级电容器器件在0.75 kW kg ^-1的功率密度下表现出39.78 Wh kg ^-1的优异能量密度，在3000次循环后的循环稳定性为91.2％的电容保持率。因此，所制备的Ni _x S _y -TRGO可能是一种先进的超级电容器电极材料。