Surface-dominant pseudocapacitive supercapacitors with high specific energy and power for energy storage

Abstract

The synergistic combination of electric double-layer capacitance (EDLC) and pseudocapacitance is one of the most effective approaches to realize high-performance supercapacitor energy storage. Herein high specific energy and power supercapacitor is realized through the surface-dominant pseudocapacitive charge storage. To demonstrate that, a hybrid 1T-MoS2/Ti3C2Tx porous aerogel is rationally fabricated via bidirectional freeze-casting. The conductive Ti3C2Tx electrically connects the 1T-MoS2 nanosheets, which significantly improves the electron transfer and ion transport, leading to the surface-dominant (up to 86.9%) pseudocapacitive energy storage. As a result, the hybrid aerogel exhibits an outstanding capacitance of 392 F g−1 at 5 mV s−1, greatly higher than the conventional 1T-MoS2/Ti3C2Tx film and 1T-MoS2 film. Meanwhile, the Ti3C2Tx-connected 1T-MoS2 architecture achieves high capacitance retention (∼ 38%) at 1000 mV s−1, which is about 2.9 and 4.7 times higher than that of conventional 1T-MoS2/Ti3C2Tx film and 1T-MoS2 film, respectively. Moreover, the asymmetric supercapacitor delivers both high specific energy (45.3 Wh kg–1 at 924 W kg–1) and specific power (76.4 kW kg–1 at 18.9 Wh kg–1), among the best records of supercapacitors. This work opens new opportunities to develop next-generation high specific energy and power supercapacitors via synergistic effects of EDLC and pseudocapacitance.