Low-cost and environmentally friendly synthesis of an Al3+ and Mn4+ co-doped Li4Ti5O12 composite with carbon quantum dots as an anode for lithium-ion batteries

Abstract

To increase the specific capacity and conductivity of lithium titanate (LTO), low-cost and environmentally friendly carbon quantum dots (CQDs) were used to composite with Al³⁺ and Mn⁴⁺ co-doped Li₄Ti₅O₁₂ (LTO-Al/Mn) to improve its electrical properties. The Al³⁺ and Mn⁴⁺ were successfully substituted for Ti located at (16d) sites in the LTO and the CQDs formed a composite with LTO-Al/Mn. The specific capacity of the first cycle at 0.1C increased to 296.5 mA h g⁻¹, and the impedance decreased to 16.8 Ω. The specific capacity maintained 236.0 mA h g⁻¹ after 100 cycles.