Abstract
Lithium-ion capacitors (LICs) have been widely explored for energy storage. Nevertheless, achieving good energy density, satisfactory power density, and stable cycle life is still challenging. For this study, we fabricated a novel LIC with a NiO-rGO composite as a negative material and commercial activated carbon (AC) as a positive material for energy storage. The NiO-rGO//AC system utilizes NiO nanoparticles uniformly distributed in rGO to achieve a high specific capacity (with a current density of 0.5 A g−1 and a charge capacity of 945.8 mA h g−1) and uses AC to provide a large specific surface area and adjustable pore structure, thereby achieving excellent electrochemical performance. In detail, the NiO-rGO//AC system (with a mass ratio of 1:3) can achieve a high energy density (98.15 W h kg−1), a high power density (10.94 kW kg−1), and a long cycle life (with 72.1% capacity retention after 10,000 cycles). This study outlines a new option for the manufacture of LIC devices that feature both high energy and high power densities.
Highlights
With the ongoing energy crisis and international impetus to mitigate environmental pollution and climate change, energy storage devices that serve as intermediaries of clean and efficient energy are attracting ever more attention among researchers [1,2,3,4,5,6,7]
Regarding the electrochemical properties of NiO-rGO composite, this study found that after 200 cycles at a current density of 0.5 A g−1, the capacity retention rate was 95.6% and the coulomb efficiency was ~100%, indicating good cycle stability
In the X-ray diffraction (XRD) pattern (Figure 1), the diffraction peak at 24.5◦ was the characteristic peak of rGO
Summary
With the ongoing energy crisis and international impetus to mitigate environmental pollution and climate change, energy storage devices that serve as intermediaries of clean and efficient energy are attracting ever more attention among researchers [1,2,3,4,5,6,7]. SCs can offer high power density (10 kW kg−1 ) and excellent cycle stability, but feature low energy density (5–10 W h kg kg−1 ), impeding their utility as singular energy storage devices [10,11,12]. These differences derive from the different energy storage mechanisms of these systems; LIBs store energy by inserting lithium ions into, or extracting them from, most electrodes, whereas SCs store energy through the adsorption/desorption of ions on the electrode surface [13]. LICs with a mass ratio of 1:3 achieved a 122 W h kg−1 energy density, a 32.3 kW kg−1 power density, and a capacity retention of 72.1% after 10,000 cycles
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