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Safety of Lithium Ion Batteries: Can there Be Zero Risk?

Marc Fontecave et Jean-Marie Tarascon
p. 44

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Source: La lettre, no. 33, May 2012

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1The electrochemical storage of energy is one of the great challenges of the twenty-first century, both for the exploitation of renewable energies and for the development of electric vehicles.

2While batteries, especially ones based on lithium (Li) ions, are highly sought after for applications requiring large quantities of energy, their cost still needs to be reduced and their user-safety improved. The Electrochemical Energy Storage Network (RS2E) organized a day of debates on these themes, entitled “Safety of Ion Lithium Batteries: Can there Be Zero Risk?”, chaired by Prof. Marc Fontecave.

3This symposium, which included presentations by international scientific experts, addressed numerous topics: materials, systems and integration into electric vehicles, potential risks, and the national federating strategy implemented under the aegis of the Ministry of the Interior.

4After a review of the different types of batteries and the safety issues surrounding this mode of storage, through a comparison of the quantity of energy stored by a battery as opposed to hydraulic or kinetic storage, the components of the battery were presented. This is a complex system where the beha­viours of the cathode, the electrolyte and the anode are never completely separate due to coupled reactions. However, all the speakers recognized the major importance of the electrolyte and its interfaces with the anode and cathode in these safety issues. Hence, while the intrinsic differences between the behaviour of lithium manganese oxide cathodes (LiMn2O4) or lithium iron phosphate cathodes (LiFePO4) are significant, they are not dominant in terms of battery safety. To further reduce risks, speakers made various suggestions to improve each component of the accumulator: adding additives and designing new salts for the electrolyte, developing new ­methods for coating active materials, leading for instance to concentration-gradient cathode materials, etc.

5The presentation of the many tests to control batteries’ safety level led the speakers to emphasize the fact that the result of some of these tests could be biased by cells designed to take the test pro­tocol into account. Therefore, even if they were all successful, they would not guarantee total safety. We must think in terms of systems rather than materials to address the safety aspect as a whole. This is why tests specifically dedicated to electric vehicles were developed, particularly fire tests in widely diverse conditions.

6The contributions of speakers from around the world showed that safety is a concern shared by all the countries involved in the transformation of transport and the development of electric vehicles. They highlighted the initiatives of the public autho­rities of the countries in question, with federating approaches similar to those that are being implemented in France. Guillaume Dederen, the Civil Security representative, reported a first interesting outcome of these actions: fires in electric vehicles with Li ion batteries can be controlled and treated in the same way as those in internal combustion vehicles.

7Manufacturers expressed their insistent wish to see efforts to standardize battery behaviour controls at national, European and even global level, so that all actors would be bound by the same requirements, regardless of the battery technology, and systems that were not properly controlled would be banned from the market.

8To conclude, by emphasizing the safety aspects surrounding batteries, this conference-debate showed that the actors concerned were fully aware of the risks involved and determined to take joint action to secure a level of safety for electric vehicles that can at least match that of internal combustion vehicles. Three such actions were envisaged: holding this conference annually, creating a communication team on safety to avoid unfounded controversies, and implementing concerted action at national level, to harmonize initiatives more effectively. Researchers are enabling the chemistry of batteries to evolve, and manufacturers are mobilized: everything calls for optimism. The main pitfall, in a highly competitive market, would be for cost considerations to prevail over safety: to prevent this from happening, strict regulation is needed.

• Programme and videos available online at

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Marc Fontecave et Jean-Marie Tarascon, « Safety of Lithium Ion Batteries: Can there Be Zero Risk? », La lettre du Collège de France [En ligne], 7 | 2015, mis en ligne le 02 novembre 2015, consulté le 21 février 2017. URL :

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