Langmuir–Blodgett Assembly of Ti3C2Tx Nanosheets for Planar Microsupercapacitors

The rapid development of miniaturized electronic devices has stimulated strong interest in planar microsupercapacitors. Titanium carbide nanosheets (Ti3C2Tx) have long been considered as an attractive electrode material for such capacitors, given their high pseudocapacitance along with large surface area. State-of-the-art studies with thin films of the nanosheets prepared by methods such as spray-coating have shown specific areal capacitances of a few tens of mF cm–2 and volumetric capacitances of up to 357 F cm–3. However, most of these results have been obtained from films with thickness over the micrometer range; with the strong interest in portable and transparent devices, it would be favorable to develop ultrathin films with comparable or even improved performance. Herein, the Langmuir–Blodgett (LB) technique is used to produce films of Ti3C2Tx nanosheets with a controllable number of layers, from a single monolayer up to 20 layers. Specific areal capacitances of 1.21 and 5.89 mF cm–2 were obtained from 10 and 20 layer films, respectively, with a retention of ∼90% after 500 cycles. In particular, the thickness of the 20 layer film is ∼140 nm, which gives a volumetric capacitance of nearly 421 F cm–3. This remarkable performance is attributed to the flat and uniform deposition of the nanosheets in high density for each layer, enabled by the LB technique. This work demonstrates how the LB technique could be utilized for creating high-performance electrodes for planar microsupercapacitors, in particular with film thickness significantly smaller than what can be typically achieved by other methods.