Two-dimensional perovskite LaNiO3 nanosheets with hierarchical porous structure for high-rate capacitive energy storage

Two-dimensional (2D) perovskite-type metal oxides with ultrathin feature of nanosheets are highly promising for electrochemical energy storage applications. Here, 2D perovskite LaNiO3 nanosheet assemblies with rich pores are prepared by facile sol-gel method and subsequent heating treatment. The crystal structure, morphology and electrochemical performance of LaNiO3can be simply tuned by adjusting the heating temperature and time. The optimized sample exhibited uniform sheet-like morphology with a thickness of ∼50 nm and a large surface area and pore volume, which achieves a high specific capacitance of 139.2 mAh g−1 at a current density of 1.0 A g−1, a good rate capability and an excellent cycle stability. What's more, the LaNiO3//graphene asymmetric supercapacitor device demonstrates a high energy density of 65.8 Wh kg−1 at a power density of 1.8 kW kg−1 and an outstanding cycling stability performance with 92.4% specific capacitance retention after 10000 cycles, which represents a critical step forward toward practical applications.