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Activated Carbon by One-Step Calcination of Deoxygenated Agar for High Voltage Lithium Ion Supercapacitor
journal contribution
posted on 2020-02-25, 22:03 authored by Ming Zhang, Junfang Cheng, Lixing Zhang, Yaoting Li, MaoSung Chen, Yao Chen, Zhongrong ShenHybrid lithium-ion
supercapacitors combine the advantages of both
the high power density of capacitors and the high energy density of
lithium batteries, where activated carbon serves as a critical cathode
material with an electric double-layer capacitance charge storage
mechanism. Here, we have demonstrated that a new activated carbon,
which was prepared by the calcination of deoxygenated agar, can greatly
enhance the specific energy of the hybrid lithium-ion supercapacitor,
assembling with a multilayer “protected-lithium anode”
and 21 m LITFSI “water-in-salt” electrolyte. The obtained
carbon material has a suitable pore volume and narrow pore-size distribution
and shows a high specific surface area up to 1672 m2 g–1 and a high specific capacitance of 210.4 F gAC–1 in “water-in-salt” electrolyte.
The assembled hybrid lithium-ion supercapacitor shows a high specific
energy of 308.3 W h kgAC–1 at a specific
power of 0.7 kW kgAC–1. In addition,
it presents an encouraging 89% retention of the initial specific energy
after 8000 charge/discharge cycles. The improvement can be attributed
to the high surface area of the carbon material and its narrow pore-size
distribution, the wide operation potential window of “water-in-salt”
electrolyte, and the high cell working voltage by using protected-lithium
anode.