What does Tesla’s new honeycomb design mean for battery circularity?
A look at second life and recycling
Dr. Kai-Philipp Kairies
In these times of unprecedented demand for batteries and their raw materials, lifecycle optimization and circularity are among the hottest topics in the battery world, particularly for electric vehicles (EV).
And as usual, the dialogue often begins and ends with Tesla.
Today, there are three main approaches to make the best use of resources in the lithium-ion battery supply chain:
Extend battery lifetime
The longer a battery lives, the fewer resource-heavy replacements it needs – simple math! Extending battery lifetime can be done on the cell level, with thoughtful system design, or through advanced battery insights. The data-driven, battery insights approach is the only option fully available to end-users. Using intelligence gleaned from advanced analytic software platforms, users can slightly adjust charging and discharging behavior resulting in 20-30% increase in asset lifespan. Not only does this save precious natural resources, but it is a massive ROI improvement over a 12 – 15-year battery lifecycle.
Give batteries a second life
After their first life in a mobile application, battery packs can be used in stationary cases with lower energy and power density requirements. In these situations, the batteries can be operated less strenuously. For example, keeping batteries between 10% and 70% state of charge in a climate-controlled environment can significantly extend their life compared to a vehicle with regular fast charging. Today, second-life projects are realized from kWh to MWh sizes, mainly driven by startups and innovation departments of OEMs.
Recycling
Raw materials such as lithium, cobalt and nickel are vital battery components. Unfortunately, nearly all the precious metals found in batteries today are sourced directly through mining operations. We are still in the early scaling stages of recycling, but there is reason for hope. The prevailing thought is that battery recycling will supplant, or at least supplement, traditional mining operations as the primary source for precious metals. This would reduce the strain placed on our limited natural resources and create a closed loop recycling journey. There is considerable investment happening in the space and the results are promising.
The work is cut out for second life solutions and it’s about to get harder
The idea of giving batteries a second live has prompted some forward-thinking companies to develop ingenious solutions tackling the challenges of deploying used batteries, including:
- Evaluating the electric properties and monetary value of the modules through testing procedures or automated data analysis of the first life,
- Using specialized power electronics that individually control modules instead of an “all in series” concept where the weakest module defines the capabilities of the entire unit,
- Creating flexible rack systems that can connect and control battery modules with different form factors, cell chemistries, and voltage levels, and
- Building operational strategies tailored explicitly to used batteries.
But a new challenge is looming and perhaps the largest one to date. Tesla and others are shifting towards cell-to-pack integration and structural battery pack designs. Instead of building a self-carrying car chassis and adding a battery, the new method uses the battery pack as a structural element of the car. This design substantially reduces material, saving weight and cost. Conversely, it also makes the battery difficult to replace.
What implications does this design shift have on the circular economy?
Looking at the Tesla Model Y, this battery consists of four identical segments of cells. The segments are separated from each other by ledges of fiber-reinforced plastic. The segments cannot be separated easily. The batteries are glued to the base and top plate, and there is an unbelievable amount of foam that seals the batteries shut—adding stiffness, reducing vibration, and keeping out moisture.
Separating the modules or even the cells of this battery pack will not be possible without an unreasonable amount of work. Even if you could get the unit out of the car and into another application, the (increasing) risk of a single-cell failure comes at the high cost of replacing an entire pack. For many second-life use cases, this cost-to-risk assessment will not make business sense.
I’d argue, given Tesla’s own statement that they “design sustainable systems that are massively scalable – resulting in the greatest environmental benefit possible,” that circularity should be top-of-mind. Not just for economic reasons but also to optimize their own supply chains. And given Tesla’s new battery pack design, their plan for circularity seems crystal clear: bypass second-life and fast-forward directly to recycling.
Instead of manually disassembling batteries and risking abuse by third parties, the direct-to-recycling solution is compelling from an OEM perspective. Shredding everything into tiny pieces and refining the metals from the slurry seems easier. This is similar to how metal is extracted from raw ore.
What led to Tesla’s recycling strategy?
For Tesla, there are many benefits to this scenario:
- By making their battery unusable for anyone else, they avoid problems of third-party companies re-using (and potentially blowing up) their batteries,
- Their intimate knowledge of the contents of the pack allows them to set up the most efficient recycling process, basically putting them in the mining business,
- As a vertically integrated company, Tesla will oversee every step of the battery lifecycle and be able to cut out third parties that want to participate in the battery’s second life.
With this being said, it’s not surprising that former Tesla CTO JB Straubel founded a battery recycling company that has successfully raised $792 million to date.
So, what’s the bottom line?
Battery circularity is already a megatrend, but not because of green ambitions. The driving force behind the trend is economics. Both second life and recycling will play a role in the future of battery storage, but continuing technology changes lead to a high degree of uncertainty in the market. The key is to find a path forward that is environmentally sustainable and economically viable.
Dr. Kai-Philipp Kairies is a scientist and entrepreneur focusing on innovative storage solutions. He worked as a battery researcher and consultant in Germany, Singapore, and California. Since 2020, he is CEO of ACCURE Battery Intelligence, an AI-driven and machine learning software company that supports electric vehicle manufacturers, electrification project managers, and fleet managers in understanding and improving their batteries’ safety, longevity, and profitability using advanced, cloud-based data analytics.
