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Page 10 of 13 Luo et al. Microstructures 2023;3:2023011 https://dx.doi.org/10.20517/microstructures.2022.41

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Figure 5. (A) Scheme of Ni N-Co N /NC//AC asymmetric supercapacitor. (B) CV curves of Ni N-Co N /NC and AC at 20 mV s .
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(C) CV curves of Ni N-Co N 0.67 /NC//AC ASC at different voltage ranges at 20 mV s . (D) GCD profiles of Ni N-Co N 0.67 /NC//AC
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ASC at different voltage ranges at 1 A g . (E) CV curves of Ni N-Co N 0.67 /NC//AC ASC at different scan rates. (F) GCD profiles of
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Ni N-Co N 0.67 /NC//AC ASC at different current densities. (G) Specific capacitance of Ni N-Co N 0.67 /NC//AC ACS calculated from
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GCD test. (H) Ragone plots comparing the Ni N-Co N 0.67 /NC//AC with other similar electrode materials. (I) Cycle performance of
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Ni N-Co N 0.67 /NC//AC ASC at 10 A g (Inset: the photo of two ASC devices connected in series to light a LED bulb and to rotate a
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fan).
operating voltage increased from 1.7 V to 1.8 V and the GCD profile could only reach 1.7 V, so 1.7 V was
finally selected as the practical working potential window. CV curves of the ACS at different sweep rates
display a pair of redox peaks and remain stable, suggesting Faraday redox characteristics and superior rate
capability [Figure 5E]. Calculated from GCD profiles in Figure 5F, the device demonstrates specific
capacitance of 80.6, 75.3, 72.4, 65.8 and 64.7 F g at 1, 2, 3, 4 and 5 A g [Figure 5G]. The capacitance
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remains 80.3% of its initial value when the current density reaches 5 A g , indicating excellent capacitive
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performance. The ASC device delivers a maximum energy density of 32.4 W h Kg at a power density of
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851.3 W Kg . Even at the maximum power density of 4254.5 W Kg , the energy density is still 26 W h Kg ,
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surpassing other similar devices reported before such as Ni N//PRPC-1k , Co N//AC ,
[53]
[52]
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[57]
[55]
B-Co N-20/NF//AC/CF , NiCo S //AC , NiCo O @Bi O //AC and Ni SeǀP//AC [Figure 5H]. After
[54]
[56]
0.85
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5000 cycles at 10 A g , the ASC device exhibited ultrahigh capacitance retention of 95.8% [Figure 5I]. The
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enhanced cycle performance of the device over a single electrode in the three electrodes system arises from
the stable structure and long cycle life of AC electrode . In addition, a LED bulb can be lighted for about
[58]
2 min and a small fan can be rotated for around 1 min with two ASC devices in series, showing its
potentially broad applications (Insets of Figure 5I).