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Nitrogen and oxygen co-doped porous carbon nanosheets as high-rate and long-lifetime anode materials for high-performance Li-ion capacitors

Liu, Mengyue, Zhang, Zhengping, Dou, Meiling, Li, Zhilin, Wang, Feng
Carbon 2019 v.151 pp. 28-35
anodes, aqueous solutions, carbon, carbonization, electrical conductivity, electrical equipment, energy, energy density, freeze drying, gelatin, ice, lithium, nanosheets, nitrogen, oxygen, potassium chloride, scales (integument), washing
The rational design and sustainable synthesis of high-performance electrode materials are crucial for the practical applications of Li-ion capacitors. Herein, we demonstrate a sustainable strategy for the synthesis of N and O co-doped porous carbon nanosheets via the extraction of gelatin from the fish scales by KCl aqueous solution, lyophilization, and carbonization followed by water washing. With the help of ice/KCl double templates, the resulting sample possesses porous nanosheet structure with the thickness of ca. 4 nm, numerous N and O heteroatoms (8.2 at.% for N, 8.4 at.% for O) derived from gelatin and good electric conductivity (111 S m−1). When used as the anode material for Li-ion storage, it shows surprising rate capability (249 mAh g−1 at 50 A g−1) and cycling performance (without decay in 10,000 cycles) in half cells. Consequently, a hybrid Li-ion capacitor based on the carbon nanosheet anode delivers a high energy density (184 Wh kg−1), an ultrahigh power density (78.1 kW kg−1), and an ultralong lifetime (with energy retention of 70% after 10 000 cycles).