10 years of torment with sulfur - and a breakthrough.
Drones have long been stalled not in the engines and not in electronics, but in batteries. The larger the battery, the longer the flight, but the less the payload can be lifted. Chinese researchers have proposed a new version of the lithium-sulfur battery, which should solve one of the main problems of this chemistry and significantly increase the operating time of drones.
The development was presented by the team under the leadership of the Tsinghua International Higher School in Shenzhen. The researchers changed the work of the lithium-sulfur battery at the molecular level: they added a special substance that is turned on only during a sulfur reaction, holds unwanted intermediate connections, and helps the charge pass through the battery with less losses.
Lithium-sulfur batteries have long been considered a possible replacement for lithium-ion cells, especially where every gram is important. The sulfur is cheap, common and theoretically allows you to store much more energy than the current batteries for commercial drones. Conventional lithium-ion batteries most often give less than 300 watt-hours by 2.2 pounds, that is, about a kilogram. For a drone, such a limit quickly turns into a choice between range, time in the air and the cargo.
The main problem of lithium-sulfur chemistry arises during charging and discharge. Inside the battery, soluble intermediate sulfur compounds are formed. They begin to move around the battery, slow down the reactions, carry the active material from the desired area and gradually reduce efficiency. Because of this, lithium-sulfur batteries for years remained promising, but capricious technology: there is a lot of energy on paper, in real operation stability is not enough.
The Chinese team decided to intervene in this process. The researchers injected an additive called a premediator for sulfur electrochemistry. In a calm state, the molecule is almost not involved in the work of the battery. When the sulfur reaction begins, the supplement is activated directly in the reaction zone, binds wandering intermediates and improves the transfer of charge.
To explain it is easier, a chemical assistant appears inside the battery, which does not interfere with the system until the right moment, and then quickly collects connections that usually cause losses. Thanks to this, the reactions go along a shorter and more effective pathway, and the electrochemical process becomes more stable with repeated charging and discharge.
The researchers also rebuilt the internal response network at the molecular level. According to them, the new scheme reduced the internal resistance of the battery by 75% compared to conventional lithium-sulfur structures. For the battery, this is an important indicator: less resistance means less energy loss, less than excess heating and more efficient power output.
In laboratory tests, the battery withstood 800 cycles of charging and dispensing, retaining almost 82% of the initial capacity. For lithium-sulfur technology, this result is especially important, because durability has always remained a weak point in this direction.
The team also assembled a prototype of a packet battery cell. It showed an energy density of 549 watt-hours by 2.2 pounds, almost twice as high as many batteries that are put on drones today. In terms of the usual units, we are talking about about 549 watt-hours per kilogram.
For drones, such an increase can immediately give a practical effect. With the same weight of the battery, the drone will be able to stay longer in the air, fly further or take more cargo. In delivery, this means longer routes without intermediate charging. When inspecting power lines, one device will be able to check more support per departure. In search and rescue operations, additional minutes in the air can become especially valuable, because the drone has to examine large areas and transmit the image to rescuers.
While the development remains laboratory, and to the mass use of the drones, the battery still needs to be brought through testing, scaling production and safety check. But the strategy itself can be more than one type of battery. The researchers believe that the molecular approach will be useful for flow batteries, lithium-metallic accumulators and battery recycling technologies.
Drones have long been stalled not in the engines and not in electronics, but in batteries. The larger the battery, the longer the flight, but the less the payload can be lifted. Chinese researchers have proposed a new version of the lithium-sulfur battery, which should solve one of the main problems of this chemistry and significantly increase the operating time of drones.
The development was presented by the team under the leadership of the Tsinghua International Higher School in Shenzhen. The researchers changed the work of the lithium-sulfur battery at the molecular level: they added a special substance that is turned on only during a sulfur reaction, holds unwanted intermediate connections, and helps the charge pass through the battery with less losses.
Lithium-sulfur batteries have long been considered a possible replacement for lithium-ion cells, especially where every gram is important. The sulfur is cheap, common and theoretically allows you to store much more energy than the current batteries for commercial drones. Conventional lithium-ion batteries most often give less than 300 watt-hours by 2.2 pounds, that is, about a kilogram. For a drone, such a limit quickly turns into a choice between range, time in the air and the cargo.
The main problem of lithium-sulfur chemistry arises during charging and discharge. Inside the battery, soluble intermediate sulfur compounds are formed. They begin to move around the battery, slow down the reactions, carry the active material from the desired area and gradually reduce efficiency. Because of this, lithium-sulfur batteries for years remained promising, but capricious technology: there is a lot of energy on paper, in real operation stability is not enough.
The Chinese team decided to intervene in this process. The researchers injected an additive called a premediator for sulfur electrochemistry. In a calm state, the molecule is almost not involved in the work of the battery. When the sulfur reaction begins, the supplement is activated directly in the reaction zone, binds wandering intermediates and improves the transfer of charge.
To explain it is easier, a chemical assistant appears inside the battery, which does not interfere with the system until the right moment, and then quickly collects connections that usually cause losses. Thanks to this, the reactions go along a shorter and more effective pathway, and the electrochemical process becomes more stable with repeated charging and discharge.
The researchers also rebuilt the internal response network at the molecular level. According to them, the new scheme reduced the internal resistance of the battery by 75% compared to conventional lithium-sulfur structures. For the battery, this is an important indicator: less resistance means less energy loss, less than excess heating and more efficient power output.
In laboratory tests, the battery withstood 800 cycles of charging and dispensing, retaining almost 82% of the initial capacity. For lithium-sulfur technology, this result is especially important, because durability has always remained a weak point in this direction.
The team also assembled a prototype of a packet battery cell. It showed an energy density of 549 watt-hours by 2.2 pounds, almost twice as high as many batteries that are put on drones today. In terms of the usual units, we are talking about about 549 watt-hours per kilogram.
For drones, such an increase can immediately give a practical effect. With the same weight of the battery, the drone will be able to stay longer in the air, fly further or take more cargo. In delivery, this means longer routes without intermediate charging. When inspecting power lines, one device will be able to check more support per departure. In search and rescue operations, additional minutes in the air can become especially valuable, because the drone has to examine large areas and transmit the image to rescuers.
While the development remains laboratory, and to the mass use of the drones, the battery still needs to be brought through testing, scaling production and safety check. But the strategy itself can be more than one type of battery. The researchers believe that the molecular approach will be useful for flow batteries, lithium-metallic accumulators and battery recycling technologies.
