A new type of battery made from electrically conductive polymers—basically plastic—could help make energy storage on the grid cheaper and more durable, enabling a greater use of renewable power. The batteries, made by Boston-based startup PolyJoule, could offer a less expensive and longer-lasting alternative to lithium-ion batteries for storing electricity from intermittent sources like wind and solar.
The company is now revealing its first products. PolyJoule has built over 18,000 cells and installed a small pilot project using inexpensive, widely available materials. The conductive polymers that PolyJoule uses in its battery electrodes replace the lithium and lead typically found in batteries. By using materials that can be easily created with widely available industrial chemicals, PolyJoule avoids the supply squeeze facing materials like lithium.
PolyJoule was started by MIT professors Tim Swager and Ian Hunter, who found that conductive polymers ticked some key boxes for energy storage. They can hold charge for a long time and charge up quickly. They are also efficient, meaning they store a large fraction of the electricity that flows into them. Being plastic, the materials are also relatively cheap to produce and sturdy, holding up to the swelling and contracting that happens in a battery as it charges and discharges.
One major drawback is energy density. The battery packs are two to five times larger than a lithium-ion system of similar capacity, so the company decided that its technology would be better suited for stationary applications like grid storage than in electronics or cars, says PolyJoule CEO Eli Paster.