A sandwich-like Ti3C2@VO2 composite synthesized by a hydrothermal method for lithium storage

Abstract

In spite of its high theoretical capacity and plentiful sources, the commercial application of vanadium dioxide is still unpractical because of its poor electrical conductivity and drastic volume changes during lithium-ion storage, resulting in poor electrochemical performance and fast capacity decay. To overcome these disadvantages, a newly 2D material, named Ti3C2 MXenes, is introduced to VO2 as a 3D framework via electrostatic attraction, forming Ti3C2@VO2 composite with a sandwich-like architecture. In the Ti3C2@VO2 composite, Ti3C2 play a role of three-dimensional matrix which not only strengthen the electron conductivity but also suppress the drastic volume changes of VO2 within the process of lithiation and de-lithiation. Meanwhile, VO2 nano particles growing between the layers of Ti3C2 act as the pillar to prevent multilayer Ti3C2 nanosheets from stacking and structure collapse. Consequently, the Ti3C2@VO2 composite exhibit better electrochemical performance and tiny volume swelling (a capacity of 365.6 mAh g−1 and a volume expansibility of 18.3% after 100 cycles at a current density of 100 mA g−1) than pure VO2. In addition, the pseudocapacitive contribution ratio is 57.4 at a scan rate of 2 mV s−1, which benefit from the sandwich-like structure with large surface and active sites, leading to better rate performance.