Low-cost energy storage solutions have the promise to make carbon-free renewable solar- and wind-generated energy readily available on the electric grid and to put more electric vehicles (EVs) on the road. However, today’s 10-year lifespan of batteries for these applications cannot compete with the 20- to 30-year lifetime of fossil-fueled power-peaking plants or the 15- to 20-year lifetime of conventional petroleum-powered vehicles. Additionally, the problem of Lithium (Li) loss capacity fade plagues today’s Li-ion battery technologies, shortening their lifespan and restricting their performance.
The cost of Li-ion energy storage systems continually falls, outpacing most competing storage technologies presently under development. But even if costs are brought below $200/kWh, the limited lifetime of Li-ion battery devices will still impede widespread market acceptance.
However, with the implementation of grid-based energy storage demonstration projects and numerous EVs on the road, hope for low-cost energy storage solutions has been renewed and technical and economic analyses are increasingly looking beyond upfront expenses in order to optimize energy storage total life-cycle costs.
Engineers at the National Renewable Energy Laboratory (NREL) have invented a passively triggered excess Li reservoir for energy storage cells to overcome the Li-loss capacity fade. This technology may greatly improve the life cycle and utility of Li-based energy storage systems for both utility and vehicle applications, extending lifetime by more than 50% while adding less than 2% to today’s cell cost.
The excess Li is uniquely released from the reservoir to maintain the cell’s capacity with no need for external circuitry or sensors to control the release. Additionally, both the volume and the mass of the internal Li reservoir are minimized within this novel invention in order to keep costs low. This invention specifies multiple locations for the Li reservoir within commercial Li-ion cells depending on the cell’s packaging and methods to engineer a controlled release rate. In addition to improving capacity retention over lifetime, the invention can also be used to greatly improve the beginning of life capacity of cells employing electrodes such as silicon that suffer from large irreversible capacity loss during their first several cycles.
For more information, please contact Erin Beaumont at:
Applications and Industries
- Energy storage
- Electric vehicles
- Extended battery lifetime by more than 50% in calendar and cycle life
- Adds less than 2% to cell cost
- Substantially increases useable energy and operating temperature range
- Multiple options for excess Li storage and release mechanism
- Improve capacity retention for electrodes (e.g. silicon) that suffer large irreversible capacity loss during formation cycles