Australia-based biotechnology company Circa Group, which produces its bio-based solvent Cyrene from waste cellulose, is participating in a project to develop the first UK industrial scale capability to reclaim and reuse the most valuable components of end-of-life electrical vehicle (EV) batteries.

The R2LIB (Reclamation, Remanufacture of Lithium Ion Batteries) project is funded by UK Research and Innovation through the Faraday Battery Challenge—an initiative aimed at developing cost-effective, high-performance and recyclable automotive batteries.

According to the IEA, the global electric car fleet exceeded 5.1 million in 2018 and is estimated to reach at least 130 million by 2030. This exponential growth is expected to lead to several millions of tonnes of spent batteries in need of recycling over the next 10 years or so. R2LIB looks to tackle this challenge by establishing a new, UK supply chain for extracting and reprocessing high-value components from end of life EV batteries.

Circa’s solvent Cyrene—dihydrolevoglucosenone—is specifically being used to recover polyvinylidene fluoride (PVDF)—a high performance polymer widely used as a binder in Li-ion battery cathodes.

Dihydrolevoglucosenone (Cyrene) is a new and very promising bio-based solvent substitute for widely used dipolar aprotic solvents (e.g. NMP) that are increasingly under threat from chemical legislation such as REACh. Dihydrolevoglucosenone can be made in two simple steps from biomass ensuring a low environmental footprint as well as economic viability. Currently, work is in progress to make the hydrogenation process more sustainable by replacing precious palladium by other non-critical transition metals. The solvent properties of dihydrolevoglucosenone are very similar to NMP, but in the absence of nitrogen or sulphur heteroatoms which lead to NO_x and SO_x emissions upon incineration, end-of-life environmental concerns are reduced.

—Sherwood et al.

PVDF processing currently relies on the use of NMP— a reprotoxic solvent, which is under intense regulatory pressure. By using Cyrene, R2LIB is helping recover a valuable polymer in a sustainable way.

As part of R2LIB, Circa is working with the University of York (which helped develop Cyrene) and a number of other partners including M-Solv (laser & robot modules for automatic handling and dismantling of batteries), ICoNiChem (recovery of cobalt, nickel and manganese), PV3 Technologies (recycled cathode production) and WMG (national facility for battery R&D).

A wide range of solvents have been investigated for the dissolution of battery grade PVDF. Very few have proved able to dissolve this high molecular weight polymer, with Cyrene being one. Early results looking at recovery from spent electrodes have indicated Cyrene’s unique properties are proving useful in separating PVDF from other black mass materials.

—Dr Rob McElroy of the University of York, who is a researcher on the R2LIB project

Established in 2006, Circa Group converts waste biomass into bio-based chemicals with its proprietary Furacell process at its prototype plant in Tasmania—a joint venture with Norske Skog. Circa’s developing product portfolio includes biosolvents, flavors and biopolymers, including Cyrene, an alternative to traditional polar aprotic solvents.

Circa’s proprietary Furacell technology enables the manufacture of levoglucosenone (LGE), a potential platform chemical having a highly functional C₆ structure, from a range of renewable waste and non-food source cellulosic feedstocks (e.g. straw, bagasse, sawdust). One use of LGE is conversion into the alternative bio-solvent dihydrolevoglucosenone (Cyrene).

Furacell is currently the only technology that allows production of LGE and Cyrene on a scalable basis. The Furacell process takes lignocellulosic material and uses a combination of catalysts and heat to form LGE, biochar and water. The vapors formed during the process are separated from the biochar, distilled and purified before subsequent catalytic hydrogenation to form (Cyrene).

Resources

• Sherwood, J., De bruyn Mario, Constantinou, A., Moity, L., McElroy, C. R., Farmer, T. J., … Clark, J. H. (2014) “Dihydrolevoglucosenone (Cyrene) as a bio-based alternative for dipolar aprotic solvents.” Chem. Commun., 50(68), 9650–9652. doi: 10.1039/c4cc04133j 

• Richardson, D.E. & Raverty, Warwick. (2016) “Predicted environmental effects from liquid emissions in the manufacture of levoglucosenone and Cyrene.” Appita Journal. 69. 344-351