Abstract: The active carbon/LiNi_0.5Co_0.2Mn_0.3O₂ (AC/NCM) composite cathode slices are successfully prepared via physical blending using (NMP+PVDF) organic system and subsequent ethanol extraction method, and the energy-power characteristics can be regulated by tuning the AC/NCM ratio. Here in this paper, the AC/NCM 1/3 weight ratio is emphatically employed as cathode and hard carbon (HC) as anode to fabricate the soft-package supercapacitor-type battery. Subsequent electrochemical tests demonstrate that the as-prepared devices perform nearly rectangular shape for CV curves and good linear correlation between voltage and time (V-t curves) in constant current charging-discharging processes. Moreover, the construction strategy of Three-dimensional Conductive Network (the weight ratio of SP/CNT/Graphene is 3/1/1) is introduced to effectively reduce the internal resistance of device. According to IEC 62660-1 standard, the highest measured energy density under 2.5~4.2 V window reaches 66.6 W·h/kg with 83.4 W·kg of power density, and the maximum power density is up to 6.5 kW·kg^-1 with 21.5 W·h·kg^-1 of energy density. The fully charged devices exhibit excellent high-temperature storage performance with 97.4% of energy retention in the case of no flatulence, and 27.5 mV·day^-1 of low average self-discharge rate after storing for 168 h at 65℃. The endurance evaluating at 14 C and 50 C show that the energy retention is up to 99.06% and 96.45%, respectively after 1000 cycles, revealing the long-life advantage of this kind of device. Furthermore, the pulse test even under the average discharge power density of 12 kW·kg^-1 indicates that the device displays excellent stability after undergoing 100 times of pulse discharge, which demonstrates potential applications in vehicle start-up, pulse devices and other fields.

Key words: supercapacitor-type battery, Li-ion, active carbon, LiNi_0.5Co_0.2Mn_0.3O₂, composite cathode