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 LiNi0.5Co0.2Mn0.3O2/SC also shows excellent cycle performance. After 80 cycles at 1 °C (1 °C = 172 mA g−1), the specific discharge capacity of LiNi0.5Co0.2Mn0.3O2/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.

Highlights

  • In aluminum electrolysis industry of China, the main components of cathode are carbon materials

  • Yuan w et al analyzed the composition of aluminum electrolysis spent cathode in detail and found that the ratio of graphite to amorphous carbon was about 1.5:1, which indicated that it still had a high degree of graphitization[4]

  • The results show that the diffusion coefficient ranges of spent cathode (SC) electrode and commercial graphite (CG) electrode are 4.2286×10-13-2.9667×10-10 cm2·s-1, 1.6346×10-14-2.8138×10-10 cm2·s-1, respectively

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Summary

Introduction

In aluminum electrolysis industry of China, the main components of cathode are carbon materials. The methods commonly used to calculate the diffusion coefficient of Li+ are galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV)[913] These methods have been widely used in the kinetics of electrode materials during charging and discharging of the battery. The aluminum electrolysis spent cathode carbon block was treated by hydrothermal method, and it was used as electrode material to assemble the battery, and its cycle performance and rate performance were studied. This may be due to the intercalation of Al3+ and Na+ during the aluminum electrolysis process, which expands the graphite layer spacing, provides a wider diffusion path for the diffusion of Li+, and provides more sites for the intercalation of Li+ All these results confirm the feasibility of aluminum electrolysis spent cathodes as anode materials for Li-ion batteries

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