In a series of articles, I am going to share my research on second life batteries. This is the first article.
What are second life batteries?
To reply to this question, I must start from the beginning. Obviously.
Lithium batteries are being widely used for two main applications:
- as stationary energy systems, to support the penetration of the renewable energies in the grid,
- and to electrify transportation, specially passenger vehicles.
Both markets are growing and competing for the resources. Prices, that we always expected to fall, are increasing. BloombergNEF data for this year shows that lithium-ion battery pack prices have gone up 7% in 2022 [1].
That is why we need to use these resources in the most efficient manner.
Now that we understand the need, let’s connect the dots. Electrical vehicles use battery packs that ranges from 10 kWh (a Mitsubishi Minicab MiEV) to 120 kWh (a Mercedes-Benz EQS).
All these batteries will be used until they reach 80% of their State of Health.
Let’s take a break here and learn some technical words.
State of Health refers to the available capacity of the battery in a certain moment. Let’s say you buy a new battery with 100 kWh capacity. The State of Health (SoH) in that moment is 100%. With time, the battery will lose capacity due to wearing and some chemical degradation. After a year and a daily use, let’s assume that the battery will be able to provide you 90 kWh. The SoH of that battery is 90%.
You will probably be asking yourself, why are we changing the batteries of the cars if their SoH is still at 80%? Why don’t we wait until it is 10% or 0%?
There are multiple reasons, one of them is related to your amygdala. Let me list them here:
- EV motors require a lot of power from the batteries (traction service). That is why the battery must be ready to supply the needed instantaneous power. When the SoH is low, the power capacity of the battery is lower than in the beginning, and the OEM cannot ensure the quality of driving.
- The reason related to your amygdala is the range anxiety. It’s the driver’s fear that the vehicle has insufficient energy storage to cover the road distance that they believe that they need.
That is why, the US Advanced Battery Consortium decided that 70 to 80% is reasonable target for a battery to reach it’s end of life [2]. Some researchers [3] have shown that the driving needs of American drivers could be met with battery capacity as low as 30%. We still need more time and real tests to decide what is the appropriate threshold.
Now that we have the battery of a car, with still 80% SoH, can’t we use it for another application, like stationary storage systems? Et voila, you managed by yourself to understand what second life batteries are.
The use of batteries after they have reached the end of their useful life is termed as ‘second-life’. To summarize, let me share what is the challenge and what is the opportunity:
The challenge
Towards 2030, the yearly volumes of discarded EV batteries are estimated to be between 112 and 227 GWh [4]. At least one third of these are expected to be fully functional with more than 80% remaining capacity and that can live for up to 20 years in a second-life application. It will be the less sustainable act to throw, or even recycle these batteries without giving them a second opportunity: a second life application.
The opportunity
In order to build renewable grid and transportation we are seeking, energy storage is a necessity, not an alternative. That is why we need the most cost efficient and resource efficient solutions, like second life batteries.
In the next article, I will focus on the possible limits for this business opportunity.
— — — — — —
Notes
[1] https://www.energy-storage.news/lithium-battery-pack-prices-go-up-for-first-time-since-bloombergnef-began-annual-survey/
[2] U. ABC, ‘US ABC Electric Vehicle Battery Test Procedures Manual, Revision 2,’ principal author: Gary Hunt, Idaho National Engineering Laboratory, US Dept of Energy Idaho Field Office.
[3] https://doi.org/10.1016/j.jpowsour.2015.01.072
[4] https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/second-life-ev-batteries-the-newest-value-pool-in-energy-storage