Porous nickel-manganese selenide composite nanosheets as binder-free electrode for ultra-stable hybrid supercapacitors

Abstract

Modernization has led to an exponential increase in the use of fossil fuels, thereby negatively impacting the environment. In this regard, electrochemical energy storage devices, such as supercapacitors (SCs), have been an attractive solution. Herein, we report the synthesis of binder-free multiphase SC electrode material synthesized based on potential transition metals, such as nickel (Ni) and manganese (Mn), coupled with a prominent chalcogen, such as Se (the resulting material being Ni₃Se₄-Mn₃O₄ composite, NMS). The synthesized NMS electrode material exhibited a high surface area owing to its nanoflake structure. The electrode showed high areal capacity and specific capacitance of 407.3 μAh cm⁻² and 40.7 mAh g⁻¹ at 3 mA cm⁻², respectively. For comparison, the optimized NMS electrode showed a higher discharge time than the other synthesized electrodes, exhibiting good cycling stability of 88.14 % and 98.9 % coulombic efficiencies (CEs) over 10,000 cycles. The NMS electrode was then coupled with a negative electrode (activated carbon/Ni foam) to fabricate a hybrid SC (HSC) device. This HSC device delivered a high areal capacitance of 661.2 mF cm⁻². The HSC device exhibited a cycling stability of 113.3 %, with 93.8 % CE over 10,000 cycles. The device exhibited energy and power density values of 206.6 μWh cm⁻² and 19,500 μW cm⁻², respectively. Also, the fabricated HSC device was used to power real-time electronic devices.