Balancing the anions adsorption and intercalation in carbon cathode enables high energy density dual-carbon lithium-ion capacitors

Abstract

The mismatch in kinetics and capacity of electrodes restricts the further improvement of lithium-ion capacitors (LICs). In specific, carbon cathode with a high specific capacity plays a crucial role in achieving the high energy density of LICs devices. Herein, the ordered-disordered hybrid carbon structure was designed and different anions storage behaviors were revealed. Benefiting from this novel method, the specific capacity of carbon cathode reached 130.1 mAh g−1 at 0.1 A g−1 in the range of 2–4.6 V with anions adsorption and intercalation mechanism. Moreover, the specific capacity still stabilized at 62.3 mAh g−1 even after 500 cycles at 5.0 A g−1 (vs. 17.6 mAh g−1 of commercial activated carbon). When assembled into dual-carbon LICs with the modified anode, the energy density was as high as 231.5 Wh kg−1 at a power density of 40.6 W kg−1, which was much superior to the present LICs devices. The energy density was still maintained at 86.2 Wh kg−1 at 5.0 A g−1 after 1000 cycles. The improved carbon cathode tactic by regulating the anions storage behavior provides a new approach for high-performance LICs.