How Aurelius cuts batteries' carbon footprint and eliminates noxious gases

Dr Athan Fox outlines new car battery production process

Some claim that the end of the Oil Age is within sight.

Governments around the world are setting ambitious targets for electric vehicles (EVs) – in the UK, plans have been announced to phase out sales of new petrol and diesel vehicles by 2040. JP Morgan estimates that electric cars would take 35 per cent of the global market by 2025.

Despite these developments, the global lead-acid battery market is forecast to reach $84billion by 2025 – driven by expansion of the automotive industry in developing countries, including Brazil. Lead batteries are used in automobiles for starting, lighting, and ignition – but you’d be excused for not knowing that lead has one of the highest recycling rates in the world. According to EUROBAT, the lead-acid battery is the world’s most recycled consumer product.

Lithium-ion batteries, used in EVs, have a long way to go in terms of a circular economy. And yet if as few as 10 per cent of our vehicles switch from petrol/diesel to electricity we will have more lithium-ion battery than lead-acid battery on our roads.

This is because your average lead battery weighs 14 to 22kg, while a Nissan Leaf battery pack is around 294kg – and a Tesla Model S 85 kWh battery pack weighs a whopping 540kg. Although the electric vehicle market is moving fast, lead-acid batteries will be around for a while – thanks to their low cost, safety and recyclability.

At Aurelius, we are piloting a process for the hydrometallurgical recovery of waste lead-acid battery paste. Basically, we recover lead from spent battery paste via an aqueous (in water) process, rather than by burning (fire).

If the battery paste is burnt, lead is recovered as an ingot. The ingots are handed over to a battery manufacturer to produce lead oxide – the active ingredient for new batteries. What we do differently is that we cut the middle step – we convert spent paste to battery-ready lead oxide without making or handling an intermediate ingot. In doing so, we:

n Reduce the carbon footprint by more than 80 per cent

n Eliminate noxious gases (such as sulphur dioxide) without running a parallel desulphurisation process

n Reduce the energy cost of the recycling process

The energy reduction is important.

First, by treating the paste through our process, we eliminate having to burn the lead sulphate (the main ingredient in waste paste). Lead sulphate requires processing temperatures of over 1,000 degrees C.

And second, one of the stages of our process is releasing, as opposed to consuming, energy. For the techies that’s around 400mWh per 1,000 tonnes of battery scrap throughput – 25 per cent of this can be converted to electricity and potentially re-used.

But the pot of gold at the end of the rainbow is the recycled lead oxide. Laboratory tests carried out by Dr Vasant Kumar at the University of Cambridge indicate this oxide can increase battery energy density by around 30 per cent. And now, thanks to Innovate UK, we are working in Brazil to translate these positive laboratory tests to real commercial outcomes.

So, to summarise, we recycle battery paste through an environmentally friendly process, which is potentially cheaper than smelting (actual cost depending on reagents); and the recycled paste, obtained through this “green” process, can produce batteries that outperform those produced from virgin lead ore. Sounds wonderful – so why isn’t everyone using it already?

We believe that one day, most lead recycling facilities will benefit from some sort of hydrometallurgical process embedded within their systems. But it will take a paradigm shift to get this new oxide into commercial lead-acid batteries – for the simple reason that battery manufacturers today are using lead ingot, not a battery-ready powder, as their starting material.

The uplift in energy density could help us bring about this change – especially if it means lower lead content for greater energy output. After all, lithium-ion batteries are continuously improving while lead-acid batteries have been (relatively) stagnant.

Our ongoing work with Tudor Baterias and Antares in Brazil could bring about this change sooner.