Diffusion coefficient analysis of aluminum electrolysis spent cathode as anode material for lithium-ion battery

Abstract

The aluminum electrolysis spent cathode (SC) was treated by hydrothermal method and used as anode material for lithium-ion battery. The purified SC material shows excellent electrochemical performance. In order to understand the diffusion behavior of Li⁺ in the SC electrode, the diffusion coefficient of Li⁺ in the SC electrode was systematically analyzed by galvanostatic intermittent titration technique (GITT), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that the diffusion coefficient (${D}_{{\text{Li}}^{+}}$) of Li⁺ in SC electrode is calculated by CV is 2.2292 × 10⁻¹¹ cm² s⁻¹, and the ranges calculated by GITT and EIS are 4.2286 × 10⁻¹³ − 2.9667 × 10⁻¹⁰ cm² s⁻¹, 4.05 × 10⁻¹³ − 3.87 × 10⁻¹² cm² s⁻¹, respectively. SC electrode exhibits better Li⁺ diffusion kinetics compared to commercial graphite (CG). In addition, the full cell of LiNi_0.5Co_0.2Mn_0.3O₂/SC also shows excellent cycle performance. After 80 cycles at 1 °C (1 °C = 172 mA g⁻¹), the specific discharge capacity of LiNi_0.5Co_0.2Mn_0.3O₂/SC full-cell can reach 94.7 mAh g⁻¹, and the capacity retention can reach 98.13%. The fast lithium-ion diffusion rate and high discharge capacity provide a feasible direction for the high value utilization of aluminum electrolysis spent cathode.