Chinese researchers have developed a new approach to significantly improve the performance of lithium-sulfur batteries, a breakthrough that could one day allow drones to fly much farther on a single charge.
The research, recently published in the journal Nature, paves the way for longer-lasting and more powerful batteries for low-altitude aviation and other fields.
Most conventional drones currently rely on lithium-ion batteries, which are approaching the limits of their energy density capacity. This energy density, the amount of energy stored per unit weight, is typically below 300 watt-hours per kilogram, creating "range anxiety" that limits flight duration.
Lithium-sulfur batteries are considered a promising alternative due to their high theoretical energy density and the abundance and low cost of sulfur.
However, in practice, these batteries face a major challenge. This is because, during charging and discharging, sulfur undergoes complex chemical processes that produce many soluble intermediates. These intermediates tend to dissolve, slowing down the reaction and wasting energy.
A team led by Tsinghua Shenzhen International Graduate School (Tsinghua SIGS) has proposed a new solution by introducing the concept of a "premediator" for sulfur electrochemistry.
"Think of it as a special additive that lies dormant inside the battery until it's needed. When the sulfur reaction begins, the additive wakes up right at the site and goes to work," explains Zhou Guangmin, a researcher at Tsinghua SIGS.
Once activated, this molecule binds to the soluble intermediates and prevents them from dissolving. The molecule also helps create a fast pathway for electrical reactions, making the entire process much smoother and more efficient, Zhou says.
The team also redesigned the reaction network at the molecular level. The newly developed molecule is capable of reducing the battery's internal resistance by 75 percent compared to conventional designs. In tests, the new battery operated stably over 800 charge and discharge cycles, retaining nearly 82 percent of its capacity.
Even more impressively, the team successfully prototyped a practical pouch cell with an energy density of 549 watt-hours per kilogram, nearly double that of most standard drone batteries currently in use.
"For drones, this is crucial. Higher energy density means longer flight times, greater payload capacity, and a wider operational range. Delivery drones can fly farther to deliver packages. Power grid inspection drones can cover more towers in a single trip. Search and rescue drones can stay in the air longer when every minute counts," Zhou explained.
The team believes their molecular design strategy can also be applied to other fields, including flow batteries, lithium-metal batteries, and even direct battery recycling,
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