Low-cost, Easy-to-integrate, and Reliable Grid Energy Storage System with 2nd Life Lithium Batteries

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OPEN 2018
La Jolla, California
Project Term:
04/24/2019 - 05/31/2022

Critical Need:

The lack of reliable and low-cost energy storage solutions (ESS) limits increased integration of renewable and distributed energy resources such as wind and solar into the nation’s power grid. Lithium-ion batteries lead other batteries in ESS performance, but they are expensive. Transportation electrification is the biggest driver for lithium-ion battery adoption: approximately 15 gigawatt-hours per year (GWh/year) of batteries will have been removed from electric cars and trucks globally by 2025, and this supply could grow to more than 200 GWh/year by 2030. As these vehicles are retired, these batteries will generate significant amounts of waste unless they are removed and recycled or used in other applications, including in ESS for the electric grid. Although used batteries can be up to 90% less expensive than new ones, the overall cost of second-life battery ESS remains high because of the time and labor required to remove, sort, evaluate, and reinstall them for use in new energy storage systems.

Project Innovation + Advantages:

The University of California, San Diego (UC San Diego) is developing a universal battery integration system that conditions used EV batteries for use in second-life applications while simultaneously providing energy storage services to the electricity grid. In principle, millions of EV batteries can be repurposed in a “second life” to provide inexpensive stationary storage for homes, businesses, and the electricity grid. It is challenging to combine batteries because batteries with different ages and usage histories perform differently and have varying amounts of remaining life. In this project, UC San Diego will develop a modular power converter matrix to control power flow to used battery modules. UC San Diego will also incorporate advanced life cycle control modeling and optimization algorithms to condition batteries for resale and create a scalable, low-cost stationary storage system.

Potential Impact:

The proposed system delivers reliable large-scale energy storage while conditioning used batteries for reuse, which will help lithium-ion technology reach cost-sensitive applications such as residential storage and backup ESS. Second-life systems could also be used to support electric vehicle charging stations, especially in remote locations or in low-income disadvantaged areas where system cost is especially important. The project will:


Provide significant amounts of economically viable and reliable energy storage resources to the grid.


Encourage widespread adoption of swapping, repurposing and reusing EV batteries, which will reduce EV cost, help conserve resources, and improve the carbon footprint of energy production and use.


Change the cost structure of the battery life cycle. Instead of hauling vehicle batteries to a centralized plant for sorting and reintegration, UC San Diego’s solution can deploy systems near locations with abundant EVs to directly recruit batteries, saving significant freight and logistics costs.


ARPA-E Program Director:
Dr. Halle Cheeseman
Project Contact:
Dr. Shijie Antoni Tong
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