Rapid Construction of LTO/CuO Heterojunctions by Active Screen Plasma for Excellent Lithium-Ion Storage

Abstract

The lower intrinsic capacity and electron/ion transfer rate of Li4Ti5O12 limit its application and commercialization in high-specific-energy batteries. In this work, Li4Ti5O12/CuO heterojunctions are constructed by depositing CuO ultrafine nanoparticles on Li4Ti5O12 nanosheets using a controllable and high-efficiency active screen plasma (ASP) technique. It is found that the rich interface and built-in electric field provided by the heterojunction enhance the electron conductivity and ionic conductivity, and density functional theory calculations confirm that the heterojunction reduces the band gap and enhances the adsorption energy for lithium ions; in the lithium storage process, the conversion reaction between CuO and lithium ions not only provides additional capacity but also the product Cu facilitates electron transport and accelerates the electrochemical process. In addition, the increase in vacancies and specific surface area due to high-energy particle bombardment contributes to the increase in conductivity and the number of active sites, and the treated sample exhibits excellent reversible capacity (182.6 mAh·g–1 at 1C), high rate performance (170.6 mAh·g–1 at 30C), and long cycle stability (136.7 mAh·g–1 after 4500 cycles at 20C) in the half-cell, and the full cell assembled with NMC811 maintained 227.4 mAh·g–1 after 700 cycles at 1C.