Compared with nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lead-acid, or other secondary batteries, Lithium Ion Batteries (LIBs) have found wide application as electrochemical power sources in mobile communications and portable electronic devices due to their high power and energy density, long storage life, low self-discharge rate, high cell voltage, and wide operating temperature range. However, less than 5% of spent lithium-ion batteries are recycled today. The currently best available technology cannot recover critical components like lithium. As Lithium-ion batteries continue to electrify our world, over 11 million tons of spent Lithium-ion batteries will be discarded through to 2030. Only 5% of spent Lithium-ion batteries reach recycling facilities globally. The remaining 95% often reach landfills or are dangerously stockpiled in many cases. Smelting followed by refining is the currently best available technology for recycling Lithium-ion batteries. These processes, however, often have unprofitable unit economics, cannot recover lithium economically, and are limited by maximum recycling efficiencies of 30-40%.

As an important cathode active material, layered LiCoO2 is usually employed in commercial LIBs. As a result, the consumption of lithium and cobalt has increased dramatically in parallel with the growth in demand for electronic equipment. Both lithium and cobalt are regarded as significant strategic metals that are expensive. Cobalt, in particular, is of relatively low abundance and costly. In addition, the tremendous expansion of the LIB market has resulted in a great deal of battery waste. In this paper, a green chemistry process will be presented that can be used to recover and recycle lithium and other electrode metals from spent lithium batteries.

A few years after the development of lithium-ion technologies, Contestabile et al. [1] published one of the early papers devoted to the description of a multi-step process for the treatment and recovery of spent lithium primary batteries [2]. Since then, many researchers have applied various methods to the development of recovery processes for spent LIBs batteries [3]. Iizuka et al. [4] separated lithium and cobalt from spent LIBs by bipolar membrane electrodialysis coupled with chelation. Li et al. [5] recycled lithium and cobalt from used LIBs with natural organic acids as leaching reagents. Zhu et al. [6] used sodium citrate and acetic acid to leach the paste components of spent LIBs. It is important to note that, because LiCoO₂ has become the leading and typical cathode active material of LIBs, most of the established recovery technologies have concentrated on the treatment of LiCoO₂.

The process uses an organic solvent to achieve high extraction efficiencies of lithium and metals and allows the organic solvent to be effectively recycled back, instead of being wasted. We have developed a hydrometallurgical method involving natural succinic acid leaching for recovery of lithium and cobalt from the cathode active materials of spent LIBs. This method has three main steps: dismantling of the battery, anode/cathode separation, and metals leaching. Our experimental data clearly show that the amount of ozone, the initial acid concentration, the S/L ratio, the temperature, and the leaching time have marked influence on the leaching efficiency of the metals. We determined that nearly 100% of cobalt and more than 96% of lithium are leached under optimized conditions: succinic acid concentration of 1.5 mol/L, ozone content of 4 vol.%, S/L ratio of 15 g /L, temperature of 70^oC, and reaction time of 40 min. These conditions result in low energy consumption, low chemical consumption, and better percentage leaching. In particular, the leaching efficiency of cobalt, which is an extremely expensive chemical, in succinic acid aqueous solution was higher than reported in earlier studies.

References

[1] M. Contestabile, S. Panero, B. Scrosati, J. Power Sources 83 (1999) 75-78.

[2] A. Chagnes, B. Pospiech, J. Chem. Technol. Biotechnol. 88 (2013) 1191-1199.

[3] J. Xu, H.R. Thomas, R.W. Francis, K.R. Lum, J. Wang, B. Liang, J. Power Sources

177 (2008) 512-527.

[4] A. Iizuka, Y. Yamashita, H. Nagasawa, A. Yamasaki, Y. Yanagisawa, Sep. Purif.

Technol. 113 (2013) 33-41.

[5] L. Li, J.B. Dunn, X.X. Zhang, L. Gaines, R.J. Chen, F. Wu, K. Amine, J. Power

Sources 233 (2013) 180-189.

[6] X. Zhu, X. He, J. Yang, L. Gao, J. Liu, D. Yang, X. Sun, W. Zhang, Q. Wang,

R.V. Kumar, J. Hazard. Mater. 250e251 (2013) 387-396.