High-Performance Quasi-Solid-State Supercapacitor Based on CuO Nanoparticles with Commercial-Level Mass Loading on Ceramic Material La_{1- x}Sr_xCoO_3- as Cathode

To evaluate the performance of supercapacitor objectively and accurately, it is critical to develop an electrode with a thickness in the hundred-micrometer range and commercial-level mass loading of active material. In this work, for the first time, high mass loading CuO as active material (10 mg cm^-2) is supported on La_1-xSr_xCoO_3- (LSC, 0 ≤ x ≤ 0.8) substrate (thickness: 500 μm) and used as a cathode for asymmetric supercapacitor. The novel and binder-free CuO/LSC73 (i.e., x = 0.3) electrode shows high areal (C_a, 5.45 F cm^-2) and specific (C_s, 545 F g^-1) capacitances. The packaged quasi-solid-state asymmetric supercapacitor with PVA/KOH gel as an electrolyte and carbon cloth as an anode, delivers an ultrahigh volumetric energy density of 4.92 mWh cm^-3 at 10 mA cm^-2 in a wide potential window of 1.4 V, which is comparable to those of lithium batteries (0.3-10 mWh cm^-3). In addition, power density of the assembled device can reach 727 mW cm^-3 at 80 mA cm^-2 with a high energy density of 3.03 mWh cm^-3. The remarkable electrochemical performance is attributed to high conductivity of the porous LSC73 substrate and uniform distributions of CuO nanoparticles, which are favorable for the rapid electron transport and effective ions diffusion.