Ternary synergistic transition metal oxalate 2D porous thin sheets assembled by 3D nanoflake array with high performance for supercapattery

[Display omitted] •2D porous trimetal oxalate thin sheets were prepared by a facile hydrothermal method.•The Mn0.4Ni0.1Co-OA thin sheets displayed BET specific surface area of 135.42 m2·g−1.•The optimized electrode showed a high specific capacity of 1141.55C g−1 at 1 A g−1.•The assembled supercapattery delivered a maximum energy density of 32.2 Wh·kg−1.•The device exhibited remarkable cyclic stability (88.13% over 15,000 cycles). Tailoring the composition and nanostructure of transition metal compounds is critical for electrochemical energy storage materials. Transition metal oxalates, which are formed by oxalic acid (OA) with transition metals, have been regarded as potential battery-type electrode material for high-performance supercapatteries due to their excellent electrochemical stability, low cost, and adjustable pore sizes, yet still limited by their low conductivity. Herein, we report a facile way for fabricating trimetal oxalates with three-dimensional (3D) architecture assembled by interwoven nanosheets by a succinct-operated hydrothermal method. Benefiting from both unique 3D porous structures and the synergistic interactions of trimetal oxalates, the developed Mn0.4Ni0.1Co-OA shows a considerably high specific capacity (1141.6 C g−1) and ultralong cyclic life (85% capacity retention over 10,000 cycles). Additionally, the supercapattery assembled with the Mn0.4Ni0.1Co-OA electrode and the activated carbon (AC) electrode displays a maximum energy density of 32.2 Wh kg−1 at the power density of 770.2 W kg−1 and outstanding cycle life (retention rate of 88.1% after 15,000 cycles). The results presented in this work that the rational design of the composition and structure of oxalates can provide a new idea for the preparation of high-performance energy storage materials.