TiO2 quantum dots confined in 3D carbon framework for outstanding surface lithium storage with improved kinetics

Pseudocapacitive lithium storage is an effective way to promote the improvement of electrochemical performance for lithium ion batteries. However, the intrinsically sluggish lithium ionic diffusion and the low electronic conductivity of TiO2 limit its capability of pseudocapacitive behavior with fast surface redox reaction. In this work, TiO2 quantum dots confined in 3-dimensional carbon framework have been synthesized by a facile process of reverse microemulsion method combined with heat treatment. The obtained composites effectively combine electrochemical redox with surface pseudocapacitive, showing excellent electrochemical properties. An ultra-high discharge capacity of 370.5 mAh/g can be retained after 200 cycles at a current density of 0.1 A/g. Ultra-long life extends to 10,000 cycles with an average capacity loss of as low as 0.00314% per cycle can be obtained at a high current density of 5.0 A/g, due to the high pesudocapacitance contribution of fast surface redox reaction. Furthermore, the practice application of the obtained electrode is also investigated in a full cell with LiCoO2 as the cathode and a high capacity retention of 93.5% is maintained after 100 cycles at the current density of 0.1 A/g. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

Pseudocapacitive lithium storage using TiO2 quantum dots confined in a 3-dimensional carbon framework shows excellent electrochemical properties with high pseudocapacitance contribution and long cycling life. The obtained composites exhibit an ultra-high discharge capacity and ultra-long life, with a high capacity retention in a full cell with LiCoO2 as the cathode.