What is a second-life battery?
In this case, the name “second-life battery” is self-explanatory. These are batteries, and/or their parts that are re-used for different applications once their first lifecycle comes to an end. Battery recycling is not only more cost effective than solely relying on first-life batteries, but it also reduces waste and avoids further depletion of naturally occurring minerals, making the transition to renewable energy more sustainable.
Most second-life batteries come from electric vehicle (EV)applications. Once the battery reaches the end of its first-life, it could be repurposed, refurbished, or recycled. Each option involves a different process outlined below:
- Repurposing:
Multiple suitable battery packs are selected and combined based on their state of health, capacity, state of charge, etc., and repurposed for different applications. - Refurbishing:
Battery packs are taken apart so that individual cells can be reconditioned and added into new modules. - Recycling:
The battery’s valuable metals (lithium,cobalt, nickel, and manganese) are extracted and recycled.
While the process of recycling batteries seems to be straightforward, the implementation of these second-life batteries is not without challenges.
Challenges in Second-Life Battery Implementation
The concept of second-life batteries holds immense promise, but it’s not without unique challenges for system manufacturers and integrators in planning. Unlike first-life batteries, the actual state of second-life batteries cannot be understood from a simple datasheet. Instead, the lasting impacts of the conditions in their first life must be taken into account.
Planning and Dimensioning
- Determining Module Requirements:
One of the primary challenges in second-life battery implementation is understanding how many modules are needed to meet Load Serving System (LSS) requirements. Unlike first-life batteries, where specifications are readily available, second-life batteries come with variables regarding their capacity and State of Health (SOH). Also, the data from the Battery Management System (BMS) such as SOH are mostly unreliable and always incorporate the highest system level, while in fact single pack/module information is required.
- Replacement Pipeline:
Planning for replacements is the key to maintaining the operational life of a battery storage facility. Having enough modules in the pipeline ensures that downtime is minimized when modules degrade or fail.
- Lifecycle Estimation:
Estimating the lifespan of a second-life battery system can be tricky. The age of the modules and their historical usage data must be carefully considered to make accurate predictions and maintain reliability of the BESS.
Safety Concerns
- Cell Condition:
As batteries age, the risk of safety-related incidents increases. Ensuring that all cells are in a safety-approved condition is vital to second-life battery integration. Aged batteries may have hidden issues that can pose risks to both personnel and the environment.
- Electrical Component Inspection:
Beyond the batteries themselves, it's important to verify the condition of all other electrical components in the system to prevent unexpected failures.
Maintenance Challenges
Operating a grid-scale BESS with a mix of second-life battery modules can be demanding. Each module's quality and performance can vary significantly, making commissioning and ongoing maintenance more complex. Stable operation must be maintained to ensure the battery facility functions efficiently.
Risk of Penalties
Inhomogeneities between modules can lead to performance discrepancies and imbalances in terms of extractable power and energy. If these imbalances lead to unplanned interruptions in the grid supply, it can result in penalties and financial losses.
Risk of claims for OEMs
Selling used batteries can be profitable for OEMs but comes with a growing risk of quality claims as sales volume rises, leading to operational challenges. Being able to perform a health and safety check on batteries intend to be used in a second life helps to manage these risks for both the OEMs and the second-life provider.
