Intercalation of Carbon Nanosheet into Layered TiO₂ Grain for Highly Interfacial Lithium Storage

Interfacial energy storage contributes a new mechanism to the emergence of energy storage devices with not only a high-energy density of batteries but also a high-power density of capacitors. In this study, success was achieved in preparing a highly ordered two-dimensional (2D) carbon/TiO₂ (C/TiO₂) nanosheet composite using commercially available organic molecules with multifunctional groups and taking advantage of the wedge effects, oxidative polymerization, and carbonization. An experiment was conducted to validate the excellent performance of this 2D composite with respect to interfacial energy storage. The coin cell with 2D C/TiO₂ nanosheet composite demonstrates a specific capacity of as high as 510 mAh g^-1 and a high specific energy of 390.9 Wh kg^-1 at a specific power of 75.9 W kg^-1 with a current density of 0.1 A g^-1, and it also remains 39.0 Wh kg^-1 at a specific power of 8.2 kW kg^-1 with a high current density of 12.8 A g^-1. The excellent electrochemical performance can be attributed to the superior artificial interface capacitive Li⁺ storage capability, which would bridge the energy and power density gap between batteries and capacitors. Meanwhile, there are two varieties of carbon derivatives, 2D carbon nanosheet stacks and exfoliated carbon nanosheets, which can be obtained by wet-chemical etching and mechanical peeling. The experimental route is simple from commercially available raw materials, and it could be scalable at a low cost and large scale, which makes it suitable for application in various fields such as energy storage, nanocatalysis, sensors, and so on.