Synergistic and capacitance effects in nanocarbon based capacitor batteries designed for superior rate capability and...

Existing lithium-ion batteries struggle to achieve high-rate discharge stability. To address this problem, this study combines resin-based carbon nanospheres with a double electric layer effect and cathode materials with lithium-ion intercalation/delithiation behavior to form a LiNi_0.6Co_0.2Mn_0.2O₂/resin-based carbon-sphere hybrid electrode. For further improvement in electron contact and tap density, the size of the carbon nanospheres was controlled by changing the synthetic parameters, and a size-matched spatial structure model of each component within the hybrid electrode was constructed. Considering the excellent rate capability of small-sized hard carbon, hard-carbon nanospheres derived from glucose were employed as the anode active material to assemble a capacitor battery. With the integration of characteristics of both lithium-ion batteries and supercapacitors, the as-prepared new capacitor battery exhibited a specific capacity of 146.1 mAh/g at 0.1C and an energy density of 474.5 Wh/kg on the cathode active material mass, a reversible capacity of 113.2 mAh/g at 1C after 200 cycles with retention of 85.3%, and the capacity remained at 82 mAh/g even at a high current rate of 10C. These results offer insights into the design of energy storage devices with excellent cycling stability and rate capability.