Chestnut shell-like Li4Ti5O12 hollow spheres for high-performance aqueous asymmetric supercapacitors

As promising electrode materials in supercapacitor, metal oxides have attracted significant attention recently. At present, it is highly desirable but remains challenging to prepare three-dimensional (3D) metal oxides hollow materials for further improving the performance of supercapacitors. Herein, 3D chestnut shell-like Li4Ti5O12 hollow sphere is successfully fabricated by using an effective hydrothermal strategy. Owing to the unique structural feature and the desirable chemical composition, Li4Ti5O12 hollow sphere displays a remarkable capacitance of 653.22 F/g at 1 A/g and keeps 88.56% over 4000 cycle. Furthermore, one aqueous asymmetric supercapacitor (ASC) is constructed based on Li4Ti5O12 and N-doped graphene oxide (NGO) which is synthesized by a facile burning method. The Li4Ti5O12//NGO ASC shows an energy density of 26.15 Wh/kg at power density of 799.83 W/kg, and yet keeps 14.45 Wh/kg even at 8.01 kW/kg. This strategy may offer a versatile idea of tailoring new type of 3D metal oxides hollow materials and opens the possibility for using in high energy storage device.