Australian Li-S batteries pass rigorous penetration tests

Australian battery research company Li-S Energy has announced its GEN3 semi-solid-state lithium-sulfur (Li-S) battery cells have successfully passed a rigorous series of nail penetration tests with the results exceeding both the civilian and US military performance standards.

The company said that over recent months it has completed a comprehensive series of nail penetration tests using multi-layer 2.5 Ah lithium-sulfur cells built on its Phase 2 micro-production line at Geelong in Victoria.

A total of 28 cells were tested, with the cells exceeding the nail penetration test requirements of the civilian UL2271 and UL2580 standards and the United States Military Performance Specifications MIL-PRF-32383/4X requested by the company’s aerospace partners.

Nail penetration tests involve penetrating the battery cell with a steel nail under precise conditions in a blast proof test chamber. Identical nail penetration tests on a fully charged 2.5 Ah Li-S Energy cell and a comparable lithium-ion cell from an internationally recognised manufacturer (2.5 Ah 21700 25R cylindrical LCO cell).

“Amid growing public concern about the safety of lithium-ion batteries and battery fires, delivering a safe battery is vitally important,” said CEO Dr Lee Finniear. “In our target markets of drones, electric aircraft and defence, a battery fire could be catastrophic, and these results show our partners that Li-S Energy battery cells are safe when penetrated and continue to work even after being damaged.”

Mark Xavier, CEO of V-TOL Aerospace, an Li-S Energy technology partner, said that these results will have a major impact on the civilian and military drone industry.

“The ability to safely and reliably operate and transport drone technology is heavily reliant on battery stability,” he said. “The Li-S Energy GEN3 cell nail penetration test results indicate a far better risk profile than current battery technology, which I believe will save lives and improve operational performance. We are looking forward to trialling the GEN3 cells in the coming months as part of our collaboration program with Li-S Energy.”

The testing was carried out on 28 2.5 Ah cells using state-of-the-art test equipment at the company’s new battery testing centre in Geelong, Victoria.

An extensive range of test conditions was applied with cells at 0%, 20%, 40%, 60%, 80% and 100% state of charge and at beginning of life, middle of life and end of life cell age.

This wide range of tests is important to show the cells remain safe irrespective of how much charge they hold or how old they are, compared with Li-ion cells, which tend to catch fire under such tests.

Li-S Energy CTO Dr Steve Rowlands explained that the test regime was carried out in accordance with accepted international industry standards and had also been extended to cover the even more rigorous US military performance test specifications.

“Our test results significantly exceeded UL2271, UL2580 and the United States Military Performance Specifications MIL-PRF32383/4X with the cells showing no leakage; no venting, fire or flame; no rupture; no explosion; no exothermic reaction or thermal runaway,” he said. “Importantly for our target markets, the GEN3 semi-solid-state Li-S cells continued to function, delivering power even after the nail was removed. This adds significant additional safety when operating a drone, electric aircraft or in military scenarios where continued power delivery is essential to avoid a catastrophic outcome.”

In the coming months the company intends to conduct a suite of safety tests including crush, external short circuit, drop, vibration, high altitude, thermal (hot/cold range), plus extensive cycle testing to meet specific partner requirements and to finalise cell performance data sheets.

Image credit: iStock.com/John D