Breakthrough for thermal batteries

  China introduces new era for high performance cathodes for thermal batteries          

Scientists in China have just made a breakthrough in thermal battery technology by developing high-performance cathodes! These innovative thermal batteries are paving the way for more efficient energy storage, proving that sometimes, the best solutions come from where you don't expect. The findings provide a mechanistical foundation for designing next-generation high-energy-density thermal batteries. Scientists have turned their attention to an unconventional yet promising technology: thermal batteries. These specialized devices excel in environments where extreme temperatures render traditional batteries ineffective. Recently, researchers have made a major leap forward by engineering a novel cathode material which dramatically elevates performance, bringing us closer to practical, high-efficiency thermal energy systems. Transition metal fluorides are widely regarded as promising cathode materials because of their high theoretical voltages and excellent thermal stability. However, in real batteries these materials tend to dissolve and migrate within the electrolyte during operation, a phenomenon often called the “shuttle effect”, causing active material loss, declining capacity and long-term structural damage.

Imagine your phone charging faster than you can say, “Where's my charger?” It’s exciting to think about how these advancements could revolutionize our everyday gadgets and renewable energy sources. Thermal batteries are a unique class of electrochemical cells designed to operate at very high temperatures, often above 300 °C. Unlike conventional lithium-ion batteries which falter under heat, thermal batteries use molten salts as electrolytes, which become ionically conductive only when heated. This allows them to deliver instantaneous energy and withstand environments which would destroy typical storage systems. These characteristics make thermal batteries indispensable in certain industries. They are used in military applications, aerospace systems, emergency power supplies and deep-well drilling equipment, settings where reliability and performance cannot be compromised. In high-temperature molten environments, active cathode particles can dissolve into the electrolyte and migrate away from their intended sites. This degradation not only reduces the usable active material but also creates side reactions which drain performance and shorten battery lifespan. Imagine trying to build a sturdy wall with bricks which keep floating away into thin air, that’s essentially what happens when cathode material dissolves in a thermal battery. Controlling this behavior has been one of the foremost obstacles to realizing high-performance thermal cells. But despite their robustness, thermal batteries have historically suffered from a central limitation: cathode performance. The new research aims to tackle this problem.

A research team led by Prof. Wang Song and Zhu Yongping from the Institute of Process Engineering of the Chinese Academy of Sciences has developed a new approach to suppressing the shuttle effect in transition metal fluoride cathodes. The team’s study focused on thermal batteries, a type of battery which operates at 350–550 °C. “Our findings provide a mechanistical foundation for designing next-generation high-energy-density thermal batteries through precise interfacial engineering,” said Prof. Wang Song, corresponding author of the study. This work not only advances the theoretical understanding of how the shuttle effect can be suppressed in molten salt systems; it also opens up new possibilities for the application of metal fluorides in other high-energy storage devices.

The new research have tackled this problem with an innovative materials design strategy. Their breakthrough centers on engineering a specialized shell around CoF₂ particles which can selectively allow beneficial ion transport while blocking harmful dissolution paths. At the core of this approach is a carbon shell derived from covalent organic frameworks (COFs). COFs are crystalline, porous materials with well-defined structures. By converting a COF precursor into a carbonaceous coating, the team harnessed its uniform sub-nanometer channels, tiny passageways about 0.54 nanometers across. So, let's keep our fingers crossed and our batteries charged, because the future is looking bright… and warm for everyone around the world.