Project title: Pressure Tolerant Lithium Sulfur Battery for Marine Autonomous Systems
Steatite Ltd, Oxis Energy Ltd, M Subs Ltd and the National Oceanography Centre have formed a collaborative partnership to develop a revolutionary pressure tolerant rechargeable battery solution based upon new, innovative lithium-sulfur (Li-S) chemistry. The growing use of autonomous underwater vehicles (AUVs) by the oil and gas industry, defence sector and scientific research organisations, together with emerging industries like deep sea mining, require new technical developments to drive the industry forward. The need to extend mission times, collecting data for longer and provide greater run time at speed requires more power. This UK consortium made up of market leading companies will use the latest lithium-sulphur chemistry to research and develop a safe rechargeable lithium battery with leading energy density and endurance.
March 2017 - Six months to go
With just six months remaining until completion, the consortium has made significant advances in battery capability through extensive design and testing. The project is now moving rapidly towards full open water trials in two deep-submergence vehicles, including NOC’s Autosub Long Range, optimised for low-power, long endurance missions.
October 2016- Project reaches half-way point
The two-year Steatite led project to develop a pressure tolerant battery pack has accomplished a new milestone. Due for completion in October 2017, the project has reached the half-way point and is now entering a crucial stage of battery development.
The first phase of the project was completed at the National Oceanography Centre (NOC) in Southampton and involved repeatedly testing Li-S cells at pressures and temperatures equivalent to those experienced at depths of 6000m.
Operating at the edge of their required limits, the latest iteration involves 12Ah cells, discharging at low temperature (4oC) and high pressure (45MPa/450atm). The results of the testing have demonstrated that the recently developed Li-S cells now deliver a comparable performance at these conditions as at ambient temperatures and pressures. Using pressure facilities at NOC, several cells have been used to perform life tests, and have now reached over 60 cycles for slow discharge, and 80 cycles of faster discharges.
Furthermore, the effective Neutral Buoyancy Energy Density (NBED) is nearly double that of the Li-ion reference cells. Higher effective NBED and lower payload will mean integrating these Li-S batteries with Marine Autonomous Systems (MAS) technology could significantly improve vehicle endurance.
Following the successful test phase, the consortia are confidently progressing to the battery development phase, driving the team ever closer to the reality of a functional battery pack that can be utilized on deep-sea MAS.
Download the full report here.
April 2016- Phase one complete
The first phase of the project is now complete. This phase involved repeatedly testing lithium-sulfur cells at pressures and temperatures equivalent to undersea depths of 6,000m. The test result have confirmed that the cell performance is unaffected by being exposed to these extreme conditions, with consistent delivery of energy.
The project milestones include
- Repeated cycling of lithium-sulfur cells under conditions replicating a depth of 6000m show consistent energy delivery performance
- No internal damage or adverse effects on the chemistry of the cells is detected
- Production of hardware and software for the associated battery management system is now underway.
The next phase of the project will complete the design work for a trial battery pack including a pressure-tolerant Battery Management System.
Funding for this project was secured through Innovate UK and the UK Ministry of Defence, through The Defence Science and Technology Laboratory (DSTL).