Achieving of Flexible, Free‐Standing, Ultracompact Delaminated Titanium Carbide Films for High Volumetric Performance and Heat‐Resistant Symmetric Supercapacitors

Abstract The volumetric performance of supercapacitors (SCs), besides the gravimetric performance, is attracting an increasing attention due to the fast development of electric vehicles and smart devices. Here, a unique design of symmetric supercapacitor material is reported with a tight face‐to‐face architecture by applying a high pressure to the delaminated Ti 3 C 2 (d‐Ti 3 C 2 ) films. The high pressure makes the d‐Ti 3 C 2 films achieve an increased density, high electron conductivity, good wettability, and abundant interconnected mesopore channels to promote ion transport efficiently, that is, more cations can intercalate/deintercalate in the charging–discharging process. As a result, with the increase of the applying pressure, the d‐Ti 3 C 2 film pressured at 40 MPa in 1 m Li 2 SO 4 exhibits an ultrahigh capacitance of over 633 F cm −3 , outstanding energy density, and cyclic stability. Especially, the corresponding SC in 1 m 1‐ethyl‐3‐methylimidazolium tetrafluoroborate/acetonitrile organic electrolyte shows a high volumetric energy density of 41 Wh L −1 , which is the highest value reported for the SCs based on MXene materials in organic electrolytes. The outstanding volumetric electrochemical performance and thermal stability of the SCs based on the ultracompact d‐Ti 3 C 2 film demonstrate their promising potential as forceful power sources for small electronic devices.