A laboratory cell beat the target the field set for itself
Lithium sulphur is a battery chemistry built from sulphur, the cheapest element used in any battery, in place of the nickel and cobalt inside a typical electric car battery today. Its appeal is weight. A battery pack that stores more energy for every kilogram it weighs lets an aircraft, a drone or a car carry less battery to go the same distance. Kenji Kakiage and 3 colleagues at ADEKA Corporation and Gunma University in Japan built a pouch cell, a flat, foil wrapped battery cell, that reached 713 watt hours per kilogram when discharged at a moderate rate and 761 watt hours per kilogram at a slower rate. Both figures were measured after only 10 formation cycles, the initial handful of charge and discharge cycles a new cell goes through before its capacity is considered stable. The result, published in the Nature portfolio journal Communications Engineering in November 2024, is nearly 3 and a half times the 220 watt hours per kilogram Battery University lists as the top of the range for nickel manganese cobalt, a lithium ion chemistry used in many electric cars today. A separate 2025 survey of 866 published test results across 184 papers states the whole lithium sulphur field has set itself a practical target of 500 watt hours per kilogram, and that the theoretical ceiling for the chemistry is 2,600 watt hours per kilogram. The Kakiage cell already clears the practical target, in a laboratory, once.
The 761 figure was measured after only 10 formation cycles at a slow discharge rate. The 498 figure comes from a production cell built by Li S Energy, source 1. The 220 and 120 figures are the top of the ranges Battery University gives for lithium ion cells sold today, source 3.
Show the numbers
| Lab record 10 cycles | 761 |
| Production cell | 498 |
| Nickel manganese cobalt | 220 |
| Lithium iron phosphate | 120 |
All 3 figures come from the same 2025 survey of 866 published lithium sulphur test results across 184 papers. The highest achieved figure in that survey is a different cell than the 761 figure earlier in this article, from a single, separately documented paper.
Show the numbers
| Theoretical ceiling | 2,600 |
| Practical target | 500 |
| Highest in the survey | 441 |
A company selling cells today came close
Li S Energy, an Australian company that builds lithium sulphur cells for drones, defence customers and electric aircraft, announced on October 29, 2024 that a full size, 10 amp hour production pouch cell from its GEN3 chemistry reached 498 watt hours per kilogram on first discharge, falling to 456 watt hours per kilogram after formation cycling. The announcement named V TOL Aerospace, developer of the Pegasus uncrewed air system, as a partner testing the cells. Unlike the Japanese laboratory cell, this is a cell already built on a production line, though it still falls a fraction short of the 500 watt hour target.
Reaching 456Wh/kg from 10Ah cells post formation places LIS at the global forefront of lithium sulfur performance.
Dr Steve Rowlands, chief technology officer of Li S Energy. Source 1.
V-TOL would like to congratulate LIS on this significant milestone achievement that has exceeded our expectations and initial requirements for our joint development of the Pegasus uncrewed air system.
Mark Xavier, chief executive of V TOL Aerospace. Source 1.
Nothing yet says how long either cell can last
Neither record cell has proven it can survive repeated charging. Kakiage and colleagues state in their own paper that longer cycle testing was still underway when it was published, and give no figure for how many cycles their 761 watt hour cell can hold its capacity beyond the first 10. The 2025 survey states that the thick, sparingly wet cell designs that reach the highest energy densities are prone to early catastrophic failure, potentially happening after just a few tens of charge cycles. Battery University states that nickel manganese cobalt lithium ion cells sold today typically last 1,000 to 2,000 cycles, and lithium iron phosphate cells 2,000 cycles or more. A car battery has to survive years of daily charging. Whether a lithium sulphur cell built for maximum weight savings can do the same is a question none of the 5 sources here answers yet.