Facile synthesis of Tremelliform Co0.85Se nanosheets for supercapacitor

Two-dimensional tremelliform Co0.85Se nanosheets were synthesized by a simple solvothermal method using ethylenediamine (EN) to control the morphology. EN acts as a strong alkalinity supplier, facilitating the formation of Co0.85Se nanosheets or nanospheres in the final product. To further explore the electrochemical application of tremelliform Co0.85Se nanosheets, an asymmetric supercapacitor (ASC) was fabricated in which tremelliform Co0.85Se nanosheets were used as the positive electrode and commercial activated carbon (AC) was used as the negative electrode. Co0.85Se//AC ASC demonstrated impressive electrochemical performances, providing an energy density of 17.8 W h kg−1 at a high power density of 3.57 kW kg−1 and a capacitance retention of 93% after 2000 charge-discharge cycles.