Co-authors​ :

 Shirshova NATASHA (UNITED KINGDOM), Thomas ROGAUME (FRANCE), Hussain NAJMI , Sang NGUYEN (UNITED KINGDOM), Marc POISSON  

Recently there has been a significant increase in research interest focusing on multifunctional materials and devices, especially multifunctional energy storage devices such as supercapacitors. This can be attributed to their ability to perform two roles simultaneously: store energy and withstand mechanical load. A conventional supercapacitor consists of an electrolyte, a separator, and two high-surface-area electrodes that are made from the same material. After adding a secondary, structural, function, it is essential that the monofunctional performance of these components is affected as little as possible. Until now the majority of the effort has been directed at the improvement of the performance or development of the individual components of structural supercapacitors especially their mechanical and electrochemical performance. However, as the technology of structural supercapacitors become more mature there are additional questions to be answered, one of these questions is what would happen if structural supercapacitor was subjected to fire. However, high temperature and the amount of heat released are not the only reported danger associated with material under fire conditions; the toxic and flammable gases emitted during the fire is another key factor which cannot be overlooked. The production of flammables gases can lead to increased heat, assisting in the growth and spread of fire, while toxic gases and smoke can result in reduced visibility and pose a serious hazard to both the environment and human health.
Here we are reporting the combustible and thermal behaviour of structural bicontinuous electrolytes and structural supercapacitors based on these electrolytes. Studied system consisted of carbon fibres as structural electrodes and blends of bisphenol A diglycidyl ether (DGEBA) with ionic liquids (ILs) as structural electrolyte. Two ionic liquids (ILs), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-TFSI) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) were used to modify the properties of DGEBA. The effect of the composition on the studied behaviour were studied using a cone calorimeter and thermal gravimetric analyser, and the gases formed during testing were analysed using FTIR. Addition of IL had a positive effect on fire properties and thermal stability of studied samples. The results obtained confirm that time to ignition, heat release rate (HRR), total mass loss as well as the composition of the gases released during tests depends on the composition of the formulations. The effect of composition on properties, such as start of thermal decomposition in air and nitrogen; ignition time, total heat release etc will be discussed.
Acknowledgements
Funding from the EPSRC grants EP/P007465/1 and EP/P007546/1 is gratefully acknowledged.