Title : Safety issues of lithium-ion cells
Abstract:
Personal electronic devices, electric cars, computers, and emergency power systems all require energy storage. Modern science offers quite a lot of them (electrochemical cells, hydroelectric power stations or thermal stores, flywheels, etc.), but there is still work to improve them.
Lithium-ion cells (LIBs) are one of the most commonly used in smartphones, laptops and electric cars. The advantages of their use are weight, Autonomy, form, can be charge even if not empty, while the biggest disadvantages are their high flammability and relatively high price. Of course, in terms of kinetic and diffusion conditions, it can be postulated that the very diffusion of ions into the porous electrode, as well as their mobility in the electrolytic medium itself, will play a significant role, but as it turns out - only during the so-called conditioning, i.e. the first charge/discharge cycles. In addition, electrostatic interactions do not cause textural and structural changes of the electrode, and thus the cyclical life of (for a example) electrochemical capacitors.
The aspect of safety in electronic devices turns out to be a huge challenge for the world of science. So far, satisfactory power and energy densities, efficiency and cell capacities have been achieved. Unfortunately, the explosiveness, thermal runaway of the cells prevents them from being used in demanding applications such as electric cars at higher temperatures. In LIBs there are different electrolytes used: flammable liquid inorganic electrolytes, and less flammable composite polymer-ceramic electrolytes, ionic liquids (IL), polymeric ionic liquids, polymer electrolytes: solvent-free polymer electrolytes (SPEs), gel polymer electrolytes (GPEs), and composite polymer electrolytes (CPEs). Also, different flame retardants are used to prevent the thermal runaway and combustion of the lithium-ion battery. Due to the low biodegradability of flame retardants, more and more often work is done on ingredients commonly available in nature, such as starch, cellulose or lignin. The main aim of the work is to present the flame retardant properties of starch in a lithium-ion cell and its influence on the electrochemical performance of the graphite anode. In order to show the flame-retardant properties of starch, the Flash point, Self-extinguishing time is determined, and then, in order to check the efficiency of the cell's operation, an electrochemical test is carried out using electrochemical impedance spectroscopy.
Audience take-away:
- It could be interesting topic for the people, who care about our planet and also about the future which is oriented on electric vehicles and the main disadvantage – flammability aspect.
- The audience could use this topic to learn more about inside processes which occur in lithium-ion cells for optimalization of the safe construction of this cell for EVs.
- This topic could be used in automotive industry, as green chemistry aspect, in electrochemical studies, kinetics and catalysis. This provide a practical solution to a problem that could simplify or make a designer’s job more efficient. It gives the improvement of the accuracy of a design of safe LIB and also information to assist in this problem.
- Combining practical knowledge with theory (learning and working in a laboratory has a very big impact on our lives).
