Mining Contract: Internal Short Circuit Detection for Improved Safety of Lithium-Ion Batteries for Mining Applications

Contract #	200-2014-58751
Start Date	9/1/2014
Research Concept	Lithium-ion batteries pose inherent safety risks in mining environments. Existing battery management systems do not directly monitor for the presence of internal shorts, nor do they possess the sensitivity needed to infer the existence of such shorts indirectly from monitored parameters until the short poses an imminent risk of triggering a thermal runaway.
Topic Area	Electrical Safety

Contract Status & Impact

This contract is ongoing. For more information on this contract, send a request to mining@cdc.gov.

A need exists to improve the safety of lithium-ion battery systems in order to reduce the risk posed by these batteries to mine workers. The Office of Mine Safety and Health Research has recognized that lithium-ion batteries, increasingly used in mining systems, pose special risks. Because of their high energy content, lithium-ion cells can be driven into thermal runaway triggered by internal short circuits, which can be caused by manufacturing defects or metallic contaminants and remain dormant for months or even years. Thermal runaway is a process where chemical decomposition reactions inside the cell proceed in a self-accelerating manner, culminating in violent failure with cell rupture and fire and/or explosion. Lithium-ion batteries pose special safety concerns because these catastrophic failures can occur under otherwise “normal” operating conditions. Further, thermal runaway of a single cell can cause cascading failure of additional cells, worsening the overall severity of the problem and increasing the safety risk.

The company TIAX has completed extensive research into the nature and mechanism of internal short circuits, developing enabling technology in the form of a sensitive, accurate, battery-monitoring system that provides early warning of the development of internal shorts in batteries. This non-invasive, cell chemistry-agnostic technology is based on high-reliability electrical markers identified during extensive research into the nature and mechanism of internal short circuits, and is informed by a number of investigations performed by TIAX into failures of lithium-ion cells in the field. The technology consists of a monitoring architecture, sensor network, and algorithms, and detects internal shorts before they pose a risk of heat build-up and thermal runaway. Detection of internal shorts allows for appropriate intervention—e.g., removal of suspect or faulty batteries from service, or immediate de-energizing to render them safe.

The functionality and effectiveness of the enabling technology have been demonstrated in TIAX laboratories over a range of use scenarios and operational environments within the last year. Prototypes have been built and tested for certain small (e.g., portable electronics) and large (e.g., vehicle) battery systems. However, to meet the specialized needs of mining applications, the short circuit detection technology must be adapted and implemented specifically for a mining-relevant battery system. Response characteristics, signal processing, and hardware parameters must be tuned under mining-relevant use scenarios (e.g., appropriate charge/discharge cycling). Finally, because battery systems for mining applications will not have the production volume of, for example, notebook computer or automotive battery systems, it will be important to provide a path to implementation that delivers the customization of the enabling technology needed for mining applications but also at acceptable unit costs.

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