Newly developed electrolyte could improve renewable energy storage

Renewable energy sources like wind and solar are essential to preserving our planet, but they present a major challenge: they don’t always produce the electricity we need. To make the most of them, we need efficient and affordable ways to store the energy they produce, so we have power even when the wind isn’t blowing or the sun isn’t shining.

Materials scientists at Columbia Engineering have focused on developing new types of batteries to transform the way we store renewable energy. In a new study published in Communication on nature, The team used K-Na/S batteries that combine inexpensive and readily available elements (potassium (K) and sodium (Na), as well as sulfur (S)) to create a low-cost, high-energy solution for long-duration energy storage.

“It’s important that we can extend the operating life of these batteries and that we can manufacture them easily and cheaply,” said Yuan Yang, the team’s leader and an associate professor of materials science and engineering in Columbia Engineering’s Department of Applied Physics and Mathematics. “Making renewable energy more reliable will help stabilize our power grids, reduce our reliance on fossil fuels, and foster a more sustainable energy future for all of us.”

New electrolyte enables K-Na/S batteries to store and release energy more efficiently

K-Na/S batteries have two major challenges: they have low capacity due to the formation of inactive solid K₂S₂ and K₂S batteries block the diffusion process and their operation requires very high temperatures (>250 °C) which require complex thermal management, thus increasing the cost of the process. Previous studies have been confronted with solid precipitates and low capacity and the search for a new technique to improve these types of batteries has been launched.

Yang’s group developed a new electrolyte, a solvent of acetamide and ε-caprolactam, to help the battery store and release energy. This electrolyte can dissolve K₂S₂ and K₂S, improving the energy density and power density of intermediate temperature K/S batteries. In addition, this allows the battery to operate at a much lower temperature (around 75°C) than previous designs, while still achieving almost the maximum possible energy storage capacity.

“Our approach achieves discharge capacities close to theory and extended cycle life. This is very exciting in the field of intermediate-temperature K/S batteries,” said study co-first author Zhenghao Yang, a doctoral student under Yang.

While the team is currently focusing on small, coin-sized batteries, their goal is to develop this technology to store large amounts of energy. If successful, these new batteries could provide stable and reliable power from renewable sources, even in low sunlight or windy conditions. The team is currently working on optimizing the composition of the electrolyte.