Could second-life EV batteries provide low-cost energy storage?
01 November 2021
Mouser_Could second-life EV batteries provide low-cost energy storage?
Large quantities of used batteries removed from scrapped electric vehicles (EVs) could become a growing problem in coming years, as the market takes off. But a combination of recycling & second-life deployment in smart energy storage systems could provide the answer, says Mark Patrick, Technical Marketing Manager at component distributor, Mouser Electronics, offering both business & environmental opportunities – especially if dismantling & testing processes can be improved…
This article was originally featured in the November 2021 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.
Fears about range anxiety are becoming less of a barrier to consumer adoption of battery-powered electric vehicles (EVs). A combination of improvements in vehicle powertrain design, expansion of charging infrastructure, more fast-charging opportunities and greater understanding (on the part of owner/drivers) is putting minds at ease. Buyers are ready to accept that today’s EVs can safely handle typical routine daily mileage, and that only a small number of exceptional trips will require a break for recharging.
On the other hand, experience with mobile phones has shown the extent to which Li-ion batteries deteriorate due to ageing and the effects of repeated charging and discharging; by the end of their phone contract, users can do less between charges and must recharge more often. In EVs, Li-ion battery degradation affects both range and performance. When battery capacity has diminished to about 80%, it is deemed no longer suitable for powering the vehicle. Reaching that point could take 8-10 years, depending on usage – but it’s worth noting that fast charging, which has been put forward as part of the solution to EVs’ range and journey-time issues, is known to reduce battery life.
Tackling the challenges of EV waste
The world is having to work out what to do with these batteries – and the challenge could be sizeable. Predictions suggest as much as 11 million tons of used batteries will need attention by 2030, according to Canadian battery recycling start-up, Li-Cycle. Market demand for EVs is set to continue growing, with some European governments already planning to ban sales of new combustion engine vehicles within the next 20 years. This could result in half a billion plug-in hybrid and electric vehicles on the world’s roads by 2040, each containing a Li-ion battery, destined soon to add to the pile.
An obvious course of action is to reclaim the materials to make new batteries. Alternatively, it could be economically and environmentally wise to utilise as much of their remaining capacity as possible before inevitably recycling. Although not good enough for use in EVs, these so-called second-life batteries can be put to work in applications where their diminishing capacity is less apparent to end-users, and hence less likely to cause anxiety. Proposed applications encompass energy storage for a variety of uses, including solar or wind-powered microgenerators, back-up power supplies, smart grid management and (poetically) powering EV charging stations.
Opportunities for the environment & business
A viable market for second-life batteries could create opportunities to generate revenue and employment, in addition to helping to solve the environmental challenges presented by large numbers of used EV batteries. Emerging technology research & advisory firm, Lux Research suggested in 2017 that the second-life battery supply could reach 65GWh by 2035. Used batteries need to be collected and dismantled, and the recovered cells need testing to identify those that are suitable for reuse and those that are not. The good cells must then be grouped with others of similar health to create a satisfactory second-life battery.
Technology companies can then build these batteries into marketable products. Some have already taken the plunge, such as UK-based Powervault, which produces smart energy-storage systems that help residential customers make use of home-generated solar or wind energy, as well as cheap off-peak energy from the grid. Home storage also helps utilities manage consumer demand and avoid excessive peaks, by offering smart tariffs based on time of use. Swedish company, Box of Energy, based in Gothenburg, has a similar approach to that of Powervault. Both companies offer products that employ second-life EV batteries, integrated with associated systems such as battery-management electronics, charging-control circuitry to handle the interface with the grid or solar/wind generator, and safety and protection systems.
The technologies and know-how to implement essential functions such as battery management and power protection are available from established suppliers such as Analog Devices, Maxim Integrated, Microchip Technology and Texas Instruments. Texas Instruments has published a reference design for a scalable battery-management system that is suited to automotive or energy-storage applications containing Li-ion batteries. Analog Devices has various reference designs covering battery management and protection, as well as a battery testing system for Li-ion batteries.
EU regulation on EV batteries is in the making and is expected to place responsibility on carmakers to keep the batteries from their vehicles out of landfill sites. The carmakers themselves are addressing the issue in several ways. Nissan Europe has joined with a group of specialist organisations examining the issue from a second-life perspective. The project has built a 1MWh prototype energy-storage system and developed a fast way to grade batteries for second-life applications that claims to reduce the grading time from over 3 hours to as little as 3 minutes.
Mouser_Could second-life EV batteries provide low-cost energy storage?...
Tesla, in its 2019 Impact Report, states that batteries are designed to outlast the vehicle, and indicates that 100% of units are recycled when the car is scrapped (typically after 130,000-200,000 miles). Based on its fleet data, Tesla claims that the scrap batteries generally retain more than 90% of their original capacity.
Volkswagen has shared its intentions to make use of second-life opportunities, as well as recycling. Research published by the company suggests it plans to use second-life batteries – as enough used batteries become available – to provide energy storage for its plants, and other projects in conjunction with suppliers and cities. The research also says that some batteries can be refurbished for reuse in EVs by replacing specific components. Those that cannot be reused or remanufactured will be dismantled and crushed to recover raw materials.
Reuse or recycle?
As market demand for EV batteries increases, the value of raw materials such as cobalt, manganese, nickel, copper and carbon, as well as lithium, is expected to increase. Market prices of some of these materials are already rising quickly and may influence battery handlers’ decisions whether to direct batteries towards second-life applications or to recycling, where the increasingly valuable materials can be reclaimed and then resold.
Improvements in the processes involved in preparing batteries for reuse and those involved in recycling could also play a part. Today, the dismantling of batteries, testing and grading cells according to capacity is predominantly a manual process.
Automation, together with faster grading (as suggested by the Nissan consortium), could help second-life batteries compete favourably with new batteries for energy storage. On the other hand, recycling can also be improved, such as through new chemical processes to produce high-grade materials for use in new batteries.
Carmakers and their OEM battery suppliers could make life easier for everyone by optimising the battery design to simplify removal from the vehicle and subsequent dismantling and separation into constituent parts. From the EV buyer’s point of view, a healthy second-life market, or profitable recycling, or both, could translate into lower overall cost of ownership.
While engineering and market forces will play a key role in working out the economic and technical issues, other questions such as the legal liability for second-life batteries, must also be considered. More regulation can be expected around second-life batteries, as applications evolve and markets grow, with new players entering the scene and a growing supply of batteries. And, as products containing second-life batteries are relatively new, more performance and reliability data needs to be collected.
Thankfully, the question of what to do with expired EV batteries is being addressed. Second-life applications and recycling both offer scope to reduce the environmental impact of EV batteries and create new employment opportunities. Each approach comes with challenges, and old batteries must make their case in competition with new batteries, as well as recycling, if they are to enjoy a second life in energy storage. Whether after the first life, or the second, recycling remains their ultimate destination.
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