Technology could increase renewable energy storage

Renewable energy sources like wind and solar are essential to sustaining our planet, but they come with a big challenge: they don’t always generate energy when we need it. To fully harness 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.

Researchers at Columbia Engineering have focused on developing new types of batteries to change the way we store renewable energy. In a new study published September 5 by Nature communication, The team used K-Na/S batteries, which combine inexpensive, abundant elements – potassium (K) and sodium (Na) – along with sulfur (S) – to create a cheap and efficient solution for long-term energy storage.

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

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

There are two major challenges with K-Na/S batteries: they have low capacity because the formation of inactive K2S2 and K2S solids blocks the diffusion process, and their operation requires very high temperatures (>250 oC), which require complex thermal management, which increases the process cost. Previous studies have struggled with solid deposits and low capacity, and a new technique has been sought to improve these types of batteries.

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, increasing the energy density and power density of medium-temperature K/S batteries. It also allows the battery to operate at a much lower temperature (around 75°C) than previous designs while achieving near maximum possible energy storage capacity.

“Our approach achieves near-theoretical discharge capacities and extended cycle life. This is very exciting for the field of mid-temperature K/S batteries,” said first-study co-author Zhenghao Yang, a graduate student at Yang’s.

The Path to a Sustainable Energy Future

Yang’s group is affiliated with the Columbia Electrochemical Energy Center (CEEC), which uses a multiscale approach to discover breakthrough technologies and accelerate commercialization. CEEC brings together faculty and researchers from across the School of Engineering and Applied Science who study electrochemical energy, with interests spanning electrons, devices, and systems. Its industrial partnerships enable breakthroughs in electrochemical energy storage and conversion.

Planning for scaling

While the team is currently focused on small, coin-sized batteries, their goal is to eventually scale up the technology to store large amounts of energy. If successful, these new batteries could provide stable, reliable power from renewable sources, even during periods of low sun or wind. The team is currently working on optimizing the electrolyte composition.