Supercapacitors charge very quickly, but their energy storage density is lower than those of Li-ion batteries. New technology may revolutionize the state of things.
Electric vehicles are becoming more and more popular: sales of EVs are going very well, drones displace delivery guys, Hyperloop is being developed in metropolitan areas. EVs maintenance and servicing infrastructure is not yet well-developed, which is one of the key problems of EVs sales around the globe. In particular, it takes quite long to charge them, especially if compared to time needed to fill up vehicles with the internal combustion engines. For this very reason charging points for EVs are constantly occupied and owners of EVs are forced to create charging points by themselves. Battery capacity also leaves much to be desired. The most popular currently available technology for the production of Li-ion batteries for compact urban vehicles implies that several hours of battery charging ensure power to operate EV for one and half or two hours. To make the use of EVs more convenient, new batteries shall be developed. They will significantly reduce the charging time or will significantly increase the energy intensity.
According to The Engineer, the British researchers have developed polymer materials that have better energy storage properties than those of Li-ion batteries as to their energy storage properties. Moreover, they may be used in supercapacitors.
As a reminder, here are key differences between supercapacitor and Li-ion battery: supercapacitor is charged in a matter of seconds, can withstand a huge number of charge cycles (nearly one million), it works efficiently at low and high temperatures, but has low power-to-weight ratio (several times lower) and energy storage capacity (lower by a factor of several dozen) than that of Li-ion, and relatively high cost of kilowatt hour.
Li-ion batteries manufacturing technology, in turn, allows for the manufacture of devices having high power-to-weight ratio and energy storage capacity. Being available at a relatively low price, they cannot boast of charging speed (hours). They have small number of charge cycles (hundreds), their lifetime is shorter if compared to supercapacitors. Furthermore, operating-temperature range of Li-ion batteries is almost limited to room indoor temperature of ±20°C.
As is often the case, breakthrough solution combining advantages of both supercapacitor and Li-ion battery was developed in a related field. By conducting experiments with the matter that was once developed for the manufacturing of contact lenses, Dr Donald Highgate, Director of Research for Superdielectrics company, jumped to the conclusion that this material was outperforming energy storage materials. Aqueous hydrocarbon polymer may be coated onto metal foil electrodes to achieve practical capacitance values of up to 4F/cm², while existing supercapacitors typically have 0.3F/cm². Researchers say, using a specially treated stainless steel electrode (the details of which are classified pending a patent application) the material achieves results of 11 to 20F/cm². If these capacitance values can be achieved in high-volume manufacturing, the resulting supercapacitors could achieve any densities up to 180Whr/kg. This indicator is comparable to capabilities of world’s best of Li-ion batteries.
As soon as EVs are equipped with final product, time to charge vehicle will take as little as several seconds. Supercapacitor may work efficiency within a large temperature range, paving the way for e-transport use in any regions of our planet. But, for the time being, this issue is subject of future work.