Electric power on board is becoming an ever-more popular option, but what will we do with old batteries? The auto industry may have a solution

Rushing to wean ourselves off fossil fuels it seems we’re building another problem for the future. What do we do with the new batteries we’re now installing once they’ve reached the end of their life?

The growth in popularity of electric cars is evident on our roads – but how many old ones do you see? Sure, there are those that have been around for a while and may have had their battery replaced, but old electric cars are still in the minority, suggesting that we haven’t yet got to the point of mass battery replacements.

The RAC Foundation reckons there’ll eventually be around 33 million electric vehicles on UK roads. At present there are around 1.6 million plug-in electric cars in the UK, so there’s a long way to go and ultimately a lot of batteries to be replaced at some point. As well as being an environmental headache it’s set to be an expensive one too. Although Tesla batteries are believed to last 10-20 years, the cost of replacement is said to be $5,000-$20,000 per car.

So while emissions are coming down, it does look like we’re pushing a ruck in the carpet in the hope that new technology will come along to help solve the problem.

I use cars as an example as it’s much harder to establish figures for the marine world, but if we continue to progress towards electric power then clearly we’ll end up with a similar issue when it comes to battery replacement.

However, recently there have been some interesting technology stories that could provide solutions. Toyota believes it may have found a way of extending the life of a lithium-ion battery with a simple injection, while it is in situ.

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Batteries become less efficient with age as they lose some of the charged particles that store the energy. Toyota’s proposed solution is to stimulate the production of new lithium ions and electrons as a result of the injection. During tests the research team claimed they were able to restore batteries to around 80% of their original capacity, a performance they could maintain for more than 100 charging cycles.

The ability to perform this restorative process in situ is also significant in helping to keep costs down, something that could be particularly important aboard boats.

There’s more testing to be done but the news has attracted a great deal of interest in the EV world.

Meanwhile, another exciting development is that of solid state batteries. Broadly speaking, existing lithium batteries consist of three key parts: an anode (negative) and cathode (positive) physically separated by a polymer layer, and these are immersed in a liquid electrolyte that allows the ions to transfer.

Photo: Andreas Lindlahr/EYOTY

In a solid state battery the separating material is a solid layer that is also the electrolyte allowing the transfer of ions between the anode and cathode. The benefits of this are said to be greater energy density (more than double that of lithium-ion batteries), and much faster charge times (by around six times).

As a result of their increased capacity solid state batteries can be smaller and lighter and are considered to be safer too.

Aside from the advantages of a more efficient cell, the issue of safety is an important one given the number of serious fires on board boats that have been attributed to battery problems. The liquid electrolyte is volatile and flammable.

A solid state battery has a thicker separating layer that is more resistant to high temperatures which helps to prevent short circuits within the battery. The thicker separator also helps to protect against the growth of spike shaped lithium formations on the anode, dendrites that can pierce the separator in a Li-ion battery and cause a short circuit. And perhaps most important of all, a solid state battery won’t catch fire even when punctured or damaged in impact.

It’s early days for the technology, though. Dealing with how the materials expand and contract when they are charged and discharged is one key issue. Another is that the separator only works at high temperatures, plus life cycles are short by comparison.

Still, the future for electric power – be it ashore or afloat – looks very encouraging.

And while ultimately the solutions are still pushing the problem further down the line, solid state batteries could provide one of the biggest steps forward to more sustainable green power.

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