Enhancing the electrochemical properties of TiNb2O7 anodes with SP-CNT binary conductive agents for both liquid and solid state lithium ion batteries

Abstract

A high performance oxide composite electrode is obtained with a two-step solid state calcined titanium niobium oxide TiNb₂O₇ (TNO) anode and super P-carbon nanotube (SP-CNT) binary conductive agents. The solid state synthesized TNO-0.2C (the proportion of CNTs in the binary conductive agent is 20% wt) anode exhibits a high reversible discharge capacity of 278.6 mA h g⁻¹ at 0.5C, a competitive rate capability with reported works that employed wet chemical methods at moderate rates (178.1 mA h g⁻¹ at 10C), and an excellent capacity retention of 92.2% after 200 cycles at 1.5C/1.5C. The enhancement in electrochemical properties of the TNO-0.2C anode is mainly attributed to the combination of the short range and long range conductive agents in the SP-CNT binary conductive system, which guarantees an efficient electronic conductive network. The Li|Li_1.3Al_0.3Ti_1.7(PO₄)₃ composite polymer electrolyte (LATP_CPEs)|TNO-0.2C solid state batteries are also assembled, which deliver a high initial reversible discharge capacity of 241.3 mA h g⁻¹ at 1C and a good capacity retention rate of 93% after 50 cycles. This work provides an efficient way to improve the electrochemical properties of TNO anodes in lithium ion batteries, especially for solid state batteries.