Researchers at Monash University in Melbourne, Australia, say they have developed lithium sulfur (Li-S) batteries that have twice the energy density of traditional lithium-ion batteries, but that is only half of the story. The other news is that those lithium sulfur batteries can charge and discharge faster than conventional batteries and are also lighter and less costly to produce. The benefits — assuming the new technology can move out of the lab and into commercial production — are longer range, faster charging electric cars and battery-powered aircraft. The breakthrough that makes all this possible it a catalyst closely related to betadine, a common household antiseptic.
Until now, lithium sulfur batteries have held promise for high density energy storage, but suffered from slow charging and discharging. The Monash researchers figured out that using a polyvinylpyrrolidone complex — a unified chemical compound with different properties than each of its three individual components — as a facilitator accelerates chemical reactions within the battery. The research was published November 15, 2024 in the journal Advanced Energy Materials.
“With discoveries centered on readily available materials, we have the opportunity to transition to manufacturing,” said Professor Mainak Majumder. PhD candidate Maleesha Nishshanke, first author of the study, said, “Inspired by the chemistry of betadine, we found a way to accelerate the charge and discharge rates.” In its announcement of the new technology, Monash University noted that lithium sulfur batteries were first invented about 20 years before then first lithium-ion batteries, which first came on the scene in the 1980s. However, early lithium sulfur batteries suffered from several drawbacks involving their internal chemistry that kept them from being widely adopted
Solving Lithium Sulfur Battery Issues
Because they use sulfur as a cathode and lithium or lithium-ion as an anode, Li-S batteries do not evenly re-deposit lithium on the anode during recharging. Chemical deposits that spread from the lithium anode degrade both the anode and electrolyte, leading to fewer charge cycles — less than half of a Li-ion battery — reduced power delivery, and the chance of short circuits or even fires. But with constant research over many years, many of those drawbacks have been overcome. The researchers are confident their lightweight tech would make a great fit in drones. They plan to demonstrate the capability of their Li-S batteries in commercial drones and eVTOL aircraft within a year.
Co-lead author of the paper Dr. Petar Jovanović believes the Li-S batteries could power commercial drones while bringing the vision of high performance, sustainable electric aviation closer to reality. “This represents a major breakthrough toward making Li-S a feasible option not just for long-haul EVs but particularly in industries like aviation and maritime that require rapid, reliable power that is crucially light-weighted,” he said. In an electric car, the Li-S batteries could power an extra 1000 kilometers on a single charge while cutting recharge time to a few hours. “Imagine an electric vehicle that can travel from Melbourne to Sydney on a single charge or a smartphone that charges in minutes. We’re on the cusp of making this a reality.”
Professor Majumder added that lithium sulfur technology typically struggles to maintain high performance without degrading quickly, but this new battery technology can handle a lot of power being taken out at once without breaking down. “We have leveraged sulfur’s unique chemistry to make a battery that is both safer and more efficient. With our new catalyst, we’ve overcome one of the last remaining barriers to commercialization — charging speed. Our catalyst has significantly enhanced the C-rate performance of Li-S batteries, demonstrated in early proof-of-concept prototype cells. With commercial scaling and larger cell production, this technology could deliver energy densities up to 400 Wh/kg. This makes it well suited for applications requiring dynamic performance such as aviation, where batteries must handle high C-rates during take-off and efficiently switch to low C-rates during cruising. Li-S batteries are also a greener alternative to the materials used in traditional Li-ion batteries, which rely on limited and often environmentally harmful resources like cobalt.”
Monash University has launched a startup called Ghove Energy to attract investment and bring this tech to market. The research team is still working on speeding up both charging and discharging times further, and reducing the amount of lithium needed per cell. With the global lithium sulfur battery market expected to be worth $209 million by 2028, Professor Majumder said Monash’s pioneering work could place Australia at the forefront of a rapidly expanding industry. “This emerging industry has the potential to create jobs, drive economic growth and establish Australia as a key player in the market. As demands for high performance batteries soars, investment in cutting edge technology will have long term benefits for job creation and economic growth.”
CATL May Be Leading The Electric Aircraft Quest
400 Wh/kg is impressive, but it is not the highest power density available. That honor may belong to CATL, which announced two years ago it expected to begin production of “condensed matter” semi-solid batteries soon. The company said the new batteries will have an energy density of 500 Wh/kg, which is significantly greater than the 300 Wh/kg that is common for the best lithium-ion batteries in use today. Wu Kai, chief scientist for CATL, said the new battery is a type of semi-solid state product with condensed electrolyte and new anode and separator materials. CnEVPost reports that CATL has built a micron-scale adaptive mesh structure that regulates inter-chain interaction forces for changes in the electro-chemical reactions of ultra-high energy density chemistries. The battery also introduces a series of innovations in isolation films as well as innovative processes, including a high energy cathode and a new type of anode, he said.
In July, CATL said its batteries “are currently being tested in planes, allowing 4 ton aircraft to take off.” It expects its batteries to be capable of powering four-passenger private aircraft on flights of up to 1,865 miles (3,000 km) over the next couple of years. That will set a high bar for lithium sulfur batteries to clear in the near future, New Atlas says.
Also two years ago, researchers in China claimed to have invented a battery with an energy density of 711 Wh/kg, although no updates on that announcement have occurred since then to our knowledge. A recent silicon composite anode battery alternative from ProLogium for EVs displayed an impressive 321 Wh/kg density, but it hasn’t yet gone into production. Wright Electric is targeting a battery with an energy density of 1000 Wh/kg.
But here’s the thing. Most of those advanced batteries are expensive. In 2023, Nio says it had a new 150 kWh semi-solid state battery with an energy density of 360 Wh/kg. Qin Lihong, co-founder and president of Nio, told the press the new battery pack, which will power its soon to be introduced ET7 model, costs as much as its ET5 sedan. High performance is a wonderful thing and aircraft manufacturers may not be as cost sensitive as automakers are, but if the lithium sulfur technology from Monash University is commercially viable, its appeal to aircraft companies may be its relatively light weight as well as low cost. Interesting times ahead for battery-powered vehicles of all types, regardless of how some countries attempt to build tariff walls to keep new technologies out.
