A facile recycling and regeneration process for spent LiFePO4 batteries

Jian Li,Bin Liu,Lihua Wang,Ya Wang,Hongming Zhou

doi:10.1007/s10854-019-01830-y

Abstract

In response to the potential environment pollution and energy waste caused by the increasing spent lithium iron phosphate batteries (LFPs), many recycling methods have been developed. Among previous studies, the physical recycling method has attracted numerous attention due to its uncomplicated process and high efficiency. This work provides a regeneration mechanism of that the organic carbon layer is in situ coated on the surface of LiFePO4 particles by the decomposition of binder so that improves the conductivity and rate capability. When serving as cathode material for lithium ion battery, the 3 h-regenerated lithium iron phosphate battery delivers an excellent electrochemical performance which shows a discharge specific capacity of 151.55 mAh g−1 at 0.2C and delivers a discharge capacity of 120.44 mAh g−1 even at 10C compared with pristine spent LFPs. It delivers a discharge capacity of 124.35 mAh g−1 in first cycle and maintains 103.12 mAh g−1 with a high capacity retention rate of 82.93% after 2000 cycles at 0.5C through 18,650 battery testing. Meaningfully, a facile and sustainable regeneration process has been demonstrated to re-synthesize LiFePO4 from spent LFPs by our study which can be reused as cathode materials for lithium-ion batteries, indicating an economical and facile method to recycle spent LiFePO4 materials in large scale.

Highlights

Lithium iron phosphate (LiFePO4, LFP) batteries are widely used in electric vehicles (EVs) and hybrid electric vehicles (HEVs) due to its long term cycle performance and high security in recent years [1–3]
The electrolyte was 1 M LiPF6 dissolved in a mixture of dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC) (1:1:1 by weight)
Cyclic voltammetry (CV) at a scan rate of 0.2 mV s−1 and electrochemical impedance spectroscopy (EIS) in the frequency range of 10 mHz to 1000 kHz were tested on the CH instrument 660D electrochemical workstation

Summary

Introduction

Lithium iron phosphate (LiFePO4, LFP) batteries are widely used in electric vehicles (EVs) and hybrid electric vehicles (HEVs) due to its long term cycle performance and high security in recent years [1–3]. Li et al [23] investigated direct regeneration procedure of recycled cathode material mixture from 600 to 800 °C with Li2CO3 and at 650 °C displayed excellent electrochemical performances. Song et al [25] investigated mechanochemical activation mechanisms and about 93.05% Fe and 82.55% Li could be recovered as F ePO4·2H2O and L i3PO4 in the mechanochemical activation process They all have detailed research on how calcination temperature repairs spent cathode material mixture, but the role played by calcination time is not discussed in detail. A facile and sustainable physical direct regeneration method was studied to repair spent LiFePO4/C without using acid, alkali solution or precipitant, alleviating the high cost of recycling It could be an ideal of calcination process for spent L iFePO4/C materials due to facile device, less process and higher economic value. Recycled cathode material mixtures were further directly regenerated at 700 °C for 2 h, 3 h, 4 h, 5 h labeled as 2h-RLFP, 3h-RLFP, 4h-RLFP and 5h-RLFP respectively in high purity N2 atmosphere

Batteries assembly

Compositional and structural characterization

Cathode material regeneration

Results and discussion

Conclusion