How we design our lifecycle models

Circular Energy Storage’s core data is built on our forecasts of how many batteries will be in use, available for reuse, and ready for recycling.

To make these forecasts as accurate as possible, we devote significant effort to understanding how batteries perform across different applications—and, importantly, how those applications themselves are used.

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Most lithium-ion batteries share a common lifecycle, but how it unfolds depends on the requirements of the application—and how those requirements change over time. Some batteries are replaced during the lifetime of the application, while others outlast it.

This makes lithium-ion batteries difficult to track and to fully understand in terms of when—and even where—they will reach end of life, especially since many applications retain value and are traded across markets. The fact that lithium-ion batteries can be reused within their original application or repurposed for entirely new ones adds further complexity to understanding their true lifecycle and final destination.

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We study why and when batteries and their host applications cease to be used or reach end of life. Based on this research, we develop a series of dynamic models:

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• The End-of-life Ratio or Battery Lifecycle

The battery lifecycle is essentially the inverse of its end-of-life ratio—answering the question: how long will the battery remain in use?

We define “end of life” as the point at which a battery is removed from its original application. This means that even if a battery is in poor condition or technically “dead,” it is not considered to have reached end of life until it is actually removed. Conversely, if a battery is still functional but is removed for other reasons, we classify it as a used battery—available either for reuse or recycling.​​

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• The Application Export Ratio

The application export ratio measures how many batteries are expected to leave their original market, where they were first placed, for export to another market, while still within their original applications.This is particularly important for portable electronics and electric vehicles, both of which are frequently traded across regions. In our forecasts, exported volumes are reallocated and accounted for within the importing markets to maintain accuracy in regional data.

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• The Battery Reuse Ratio

The battery reuse ratio measures the share of used batteries that will be reused, stored for future reuse, or sent directly for recycling.

This applies to batteries that have reached the end of their first life and are typically handled by professional organizations that assess their condition and determine their next use.

The inverse of this metric is the recycling ratio—the proportion of used batteries that will go directly to recycling rather than reuse.

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Update Cycle and Methodological Notes

CES began developing its lifecycle models in 2017 and has updated them at least annually since then. The research supporting these updates is published in our annual report, The Battery Lifecycle Report, which was first released in 2021 and again in 2025. Going forward, it will be issued as an annual publication, with the possibility of interim updates when significant changes occur that directly affect any of the major battery segments and materially influence the underlying datasets.