A 29.3 Wh kg-1 and 6 kW kg-1 pouch-type lithium-ion capacitor based on SiOx/graphite composite anode

Lithium-ion capacitors are considered as a promising energy storage device to combine the high energy of lithium-ion batteries and high power of supercapacitors, and it is urgently required to evaluate the energy storage capability of lithium-ion capacitors from practical perspectives. In this work, a pouch-type lithium-ion capacitor is constructed using commercial SiOx/graphite as anode and activated carbon as cathode. Due to the outstanding tap density and electrical conductivity of SiOx/graphite anode, the reversibility and charge storage of lithium-ion capacitor pouch is greatly improved, which can function stably within a wide voltage window of 1-4 V to achieve a maximum gravimetric energy and power density of 29.3 Wh kg(-1) and 6 kW kg(-1), respectively (based on the total weight of pouch). Moreover, the volumetric energy and power density of this pouch also reach 50 Wh L-1 and 10 kW L-1 (based on the total volume of pouch), respectively. The achievement of both gravimetric and volumetric energy performances promises a bright future for of lithium-ion capacitors toward electrical applications where large energy-storage in limited space is demanded.