BEIJING -- Chinese researchers have developed a new approach to significantly enhance the performance of lithium-sulfur batteries, a breakthrough that could one day enable drones to fly much farther on a single charge.

The study, recently published in the journal Nature, opens a new path toward longer-lasting, more powerful batteries for low-altitude aviation and beyond.

Most conventional drones currently rely on lithium-ion batteries, which are approaching their energy density limits. Their energy density -- the amount of power stored per unit of weight -- typically falls below 300 watt-hours per kilogram, leading to the "range anxiety" that restricts flight duration.

Lithium-sulfur batteries are considered a promising alternative due to their high theoretical energy density, as well as the abundance and low cost of sulfur. However, in practice, these batteries have faced a major hurdle, as during charging and discharging, sulfur undergoes a complex chemical process that generates lots of soluble intermediates. These intermediates tend to drift away, slow down the reactions, and waste energy.

A team led by Tsinghua Shenzhen International Graduate School (Tsinghua SIGS) has proposed a new solution by introducing a "premediator" for sulfur electrochemistry.

"Think of it as a special additive that sleeps inside the battery until it is needed. When the sulfur reaction starts, the additive wakes up right where the action is and begins to work," explained Zhou Guangmin, a researcher at Tsinghua SIGS.

Once active, this molecule grabs onto the soluble intermediates and keeps them from drifting away. It also helps build fast lanes for the electrical reactions, making the whole process much smoother and more efficient, Zhou said.

The team also redesigned the reaction network at the molecular level. The newly developed molecule reduces the battery's internal resistance by 75 percent compared to conventional designs. In tests, the new battery ran stably for 800 charge-discharge cycles, retaining nearly 82 percent of its capacity. More impressively, the team constructed a practical prototype pouch cell with an energy density of 549 watt-hours per kilogram, nearly double that of many standard drone batteries currently in use.

"For drones, this matters a lot. Higher energy density means longer flight times, bigger payloads, and more working range. A delivery drone could fly farther to drop off packages. A power line inspection drone could cover more towers in one go. A search-and-rescue drone could stay in the air longer when every minute counts," Zhou said.

The team believes their molecular design strategy can also be extended to other fields, including flow batteries, lithium-metal batteries, and even direct battery recycling processes.