Storage

Harvard University is developing an innovative grid-scale flow battery to store electricity from renewable sources. Flow batteries store energy in external tanks instead of within the battery container, permitting larger amounts of stored energy at lower cost per kWh. Harvard is designing active material for a flow battery that uses small, inexpensive organic molecules in aqueous electrolyte.

Sharp Laboratories of America and their partners at the University of Texas and Oregon State University are developing a sodium-based battery that could dramatically increase battery cycle life at a low cost while maintaining a high energy capacity. Current storage approaches use either massive pumped reservoirs of water or underground compressed air storage, which carry serious infrastructure requirements and are not feasible beyond specific site limitations. Therefore, there is a critical need for a scalable, adaptable battery technology to enable widespread deployment of renewable power.

The University of California, Los Angeles (UCLA) and NASA's Jet Propulsion Laboratory (JPL) are creating cost-effective storage systems for solar thermal energy using new materials and designs. A major drawback to the widespread use of solar thermal energy is its inability to cost-effectively supply electric power at night. State-of-the-art energy storage for solar thermal power plants uses molten salt to help store thermal energy. Molten salt systems can be expensive and complex, which is not attractive from a long-term investment standpoint.

Led by Massachusetts Institute of Technology (MIT) professor Donald Sadoway, the Electroville project team is creating a community-scale electricity storage device using new materials and a battery design inspired by the aluminum production process known as smelting. A conventional battery includes a liquid electrolyte and a solid separator between its 2 solid electrodes. MIT's battery contains liquid metal electrodes and a molten salt electrolyte.

EaglePicher Technologies is developing a sodium-beta alumina (Na-Beta) battery for grid-scale energy storage. High-temperature Na-Beta batteries are a promising grid-scale energy storage technology, but existing approaches are expensive and unreliable. EaglePicher has modified the shape of the traditional, tubular-shaped Na-Beta battery. It is using an inexpensive stacked design to improve performance at lower temperatures, leading to a less expensive overall storage technology.

PolyPlus Battery Company, in collaboration with SCHOTT Glass, will develop flexible, solid-electrolyte-protected lithium metal electrodes made by the lamination of lithium metal foil to thin solid electrolyte membranes that are highly conductive. Past efforts to improve lithium cycling by moving to solid-state structures based on polycrystalline ceramics have found limited success due to initiation and propagation of dendrites, which are branchlike metal fibers that short-circuit battery cells.

Ionic Materials will develop a lithium metal (not lithium ion) rechargeable battery cell that employs a novel solid polymer electrolyte that enables the world’s first truly safe lithium metal rechargeable battery cell. Scientists at the City University of New York have found that Ionic Material’s proprietary ionic conducting polymer is the most highly lithium conducting solid state polymer material ever measured (at room temperature).

Sila Nanotechnologies will develop solid-state ceramic lithium batteries with high energy density. Traditional methods using ceramic electrolytes significantly reduces a battery’s volumetric energy density because the materials are relatively bulky. Commercially produced separator membranes are also expensive and thick because of challenges in fabrication and handling of thinner, defect-free solid-state electrolyte membranes. In addition, such membranes are often air sensitive, have low ionic conductivity, and are susceptible to the growth of branchlike metal fibers called dendrites.

The Washington University team will develop new membrane separators for redox flow batteries using a styrene-ethylene-butylene block copolymer. The team will investigate three types of membrane construction to achieve the high levels of ion selectivity and mechanical stability necessary for use in flow batteries. If needed, the team will also explore the addition of inorganic silica particles in the polymer membrane to enhance selectivity.

The University of Delaware (UD) with their project partners will develop a new class of hydroxide exchange membranes (HEMs) for use in electrochemical devices such as fuel cells. Hydroxide exchange membrane fuel cells (HEMFC), in contrast to PEM fuel cells, can use catalysts based on low-cost metals as well as inexpensive membranes and bipolar plates. However, a low-cost HEM that simultaneously possesses adequate ion conductivity, chemical stability, and mechanical robustness does not yet exist.