Material scientists at the Department of Applied Physics and Applied Mathematics, Columbia University, combined potassium (K) and sodium (Na) with Sulfur (S) to create a high-energy, low-cost solution for storing energy for longer durations.

The report, ‘Designing electrolytes with high solubility of sulfides/disulfides for high-energy-density and low-cost K-Na/S batteries,’ was published in Nature Communications.

Storing energy from renewable sources like solar and wind has always been a significant challenge due to production fluctuations based on sunlight and wind conditions.

Columbia University’s research focuses on finding low-cost and high-energy battery storage solutions to address the issue of long-duration energy storage.

The Na/S batteries utilize advanced electrolytes that dissolve polysulfides and sulfides, significantly enhancing reaction kinetics, specific capacity, and energy density.

The report said these batteries operate at nearly the theoretical capacity (1655 mAh g⁻¹ sulfur) at 75 °C with a 1 M sulfur concentration. When the sulfur concentration is increased to 4 M, they provide 830 mAh g⁻¹ at a current density of 2 mA cm⁻², maintaining 71% of their capacity after 1000 charge-discharge cycles.

The K-Na/S battery, with an energy density of 150-250 Wh kg⁻¹, uses only earth-abundant materials, making it a promising solution for long-duration energy storage.

Headed by Yuan Yang, Associate Professor of Materials Science and Engineering in the Department of Applied Physics and Mathematics at Columbia University, the scientists have developed a new acetamide or CPL-based eutectic solvent electrolyte. This electrolyte can dissolve K₂S₂ and K₂S to enhance the energy density and power density of K/S batteries. It also enables the batteries to operate at much lower temperatures of about 75°C.

The report said that experimentally, a nearly theoretical discharge capacity of 1655 mAh g−1 is achieved with 1 M sulfur in the catholyte at 75°C, 2.6 times that with conventional TEGDME electrolytes.

The researchers are now focused on small, coin-sized batteries, but they eventually plan to scale up the technology to store large amounts of energy.

Universities worldwide have been researching potential breakthrough battery solutions and energy storage. Recently, MIT scientists found a potential cathode material that can disrupt the future of battery technology. The study reveals a new class of partially disordered rock salt cathode, integrated with polyanions —disordered rock salt-polyanionic spinel that delivers high energy density at high voltages with significantly improved cycling stability.

Another study by Stanford University claimed that they have made progress on an emerging technology that uses liquid organic hydrogen carriers to essentially create a ‘liquid battery’ for storing renewable energy from wind and solar power.