Recycling of Spent Lithium Ion Batteries Using Sulfuric Acid with Detailed Mass Balance
Authors: Anwani Sandip , Methekar Ravi N. , Ramadesigan Venkatasailanathan 
Published: February 2020

Lithium ion batteries (LIBs) are one of the most commonly used batteries in portable electronic devices such as mobile phones, calculators, wrist watches because of advantages like high energy density, low self-discharge, light in weight. Heavy consumptions of Li-ion batteries and its subsequent disposal to landfills or incineration adversely impact the environment. A method needs to device to dispose these huge amounts of e-waste of LIBs economically and effectively. Recycling of the LIBs is studied in literature thoroughly. [Barik et al., Contestabile et al., Dorella., li et al., Zeng et al., Li et al., Meshram et al; Zhang and Cheng., Babjak et al] where the primary objective is to demonstrate the methodology of the battery recycling process.
In this talk, we will present the detailed mass balance of each and every step of the acidic leaching of the LIBs. A holistic approach has been developed towards the recycling of spent LIBs in which Sulfuric acid leaching was applied to recover the lithium carbonate, cobalt oxalate and manganese oxide from the cathodic active materials of spent LIBs using sodium bisulphite as a reducing agent.
The recycling of the spent LIB can be broadly classified into three steps viz. 1) Peeling of the active cathode materials, 2) Dissolution of active cathode materials and 3) extraction of valuable materials. The leaching parameters such as concentration of Sulfuric acid, solid to liquid ratio, leaching time, temperature were optimised for the dissolution of valuable metals.
A single lithium-ion battery of mass 20g has been taken for the analysis. The battery was completely dismantled manually and a mixture of cathode strip (6.4g) with 50ml of N-Methyl-2-Pyrrolidone (NMP) was sent for ultra-sonication cleaning for the removal of Al-foil (3g). After sonication the slurry material has been centrifuged to settle down the active cathodic mass of 3.4g. The wet active cathodic material was calcined at 700°C for 5 h in which around 20% loss in weight was observed due to decomposition of binder and active carbon material. The complete process of peeling of cathode active materials is shown in Figure 1. The calcined material was subsequently ball milled followed by sieving to get the particle size of less than 25 µm. The remaining 2.312 g of active material was leached with 2 M H2SO4 at 95°C for 2 h for extraction of valuable metals in their respective oxalates and carbonated forms with the aid of stoichiometric quantities of oxalic acid and sodium carbonate solution. The schematic of leaching is shown in Figure 2. A dissolution efficiency of about 95% was achieved. It was found that the dissolution efficiency greatly increases by using finer particles in leaching. Using this process, high recovery of lithium carbonate and cobalt oxalate could be achieved from the solution. In future work, lithium cobalt oxide will be formed using lithium carbonate and cobalt oxalate by calcining at appropriate temperature. Once the lithium cobalt oxide is formed, coin cells will be fabricated and tested using battery analyzer for charging and discharging cycles.

Acknowledgement

The authors would like to acknowledge the financial supports from Departmental of Science and Technology, Government of India under the scheme of SERB-ECR (ECR/2016/000422).

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Figure 1