Lithium-ion (Li-ion) batteries have been highly touted for their long lifespan, high discharge rate, and ability to perform effectively in a number of different energy storage applications, which has led to their widespread adoption across the consumer electronics, automotive electrification, and utility grid energy storage sectors. The key factors driving the design and application of Li-ion battery technologies include power capacity, energy capacity, cost, lifespan and safety. On the cost side, Navigant Research sees the maturation of the automotive and energy storage manufacturing and supply chains creating market forces that are expected to drive costs to new lows. However, the safe transport and use of Li-ion batteries is paramount and must be factored into each step of the manufacture, sale, transport, and use phase of the battery.
Since Li-ion cells are shipped partially charged to maximize their lifespan and reduce the chance of oxidation over time, they are classified as dangerous goods for transport, according to the United Nations (UN) Model Regulation for the Transport of Dangerous Goods. Further, it has been well-documented that heat generation coupled with metal contamination and poor battery management systems can increase the risk of thermal runaway and fires during the use phase of a Li-ion battery. Whereas design, manufacturing, and quality control improvement have been implemented to reduce these risks during battery use, new scrutiny is being placed on the air transport of partially charged Li-ion cells and battery packs due to combustion risk from extreme temperatures. These developments are creating a challenge for Li-ion battery manufacturers that are considering export strategies due to the increasingly complex set of regulatory challenges facing airline carriers.
- In 2014, the U.S. Department of Transportation aligned domestic regulations with the more stringent international dangerous good standards.
- The International Civil Aviation Organization (ICAO) and the International Air Transport Association (IATA) has established specific standards for testing Li-ion batteries that are shipped on their own or contained in equipment.
- In the United States, the Transportation Security Administration now states that while there is no explosion hazard associated with these batteries, the Federal Aviation Administration has studied fire hazards and no longer allows large, palletized shipments of these batteries to be transported as cargo on passenger aircraft.
Assessing and Addressing the Risks
To address safety risks during transport and use, scientists at NTT Facilities, Inc. have tested adding a chemical flame retardant called phosphazene to lithium batteries to increase their safety in different applications. Their study has shown that fully charged 200 Ah packs, like those commonly used in portable electronics, did not explode, ignite, or undergo thermal runaway when undergoing significant laboratory testing protocols. Further, larger battery packs were also tested and operated for 400 days in a state of floating charge with positive results and minimal impact to battery capacity.
Though this advancement is still in the early stage of development, the prospect of integrating a material that is commercially available with a high voltage resistance and low cost to further improve safety while balancing costs merits a watchful eye. Whereas battery manufacturers are loath to add materials, those battery manufacturers and energy storage system integrators looking to ship (or procure) Li-ion batteries from long-distance manufacturing sites will want to track these developments.