What makes hyrbid supercapacitors safer and more reliable than ever?

The safety of a system comes in layers. If a safety issue exists, then it has to be addressed at multiple levels. The first level is prevention, i.e. making sure by design or by technology choice that the safety risk doesn’t exist at all. This is the level where hybrid supercapacitors offer intrinsic safety and reliability. Nevertheless, hybrid supercapacitor battery packs can store and release enormous amounts of electric energy. Just like with any such system, general principles of safety with power electricity still apply. Let’s now focus on the inherent safety of the technology:

• Electrolyte: while the power capacitors contain a small amount of electrolyte, its purpose is mainly to act as a filler and as a pathway for the charges to move. The electrolyte is soaked up by the nano-carbon material, so that even when the cell’s skin is breached, very little or none will leak out.
• Use of Nickel and Cobalt. These metals offer a trade-off between energy and power density. More Nickel means more energy, more cobalt means more stability. The 18650 cells for example contain no Nickel but provide a high power density. The metals are only present on one electrode and bound in specific compounds so that no free metal ions can create dangerous dendrites.
• The hybrid supercapacitors come in different variants that reflect the dominant lithium-ion battery technologies. This provides a trade-off between price, safety, reliability, and performance (energy density vs. power density) but as the cell still functions as a (super) capacitor with the electric energy being stored as electric charges with no active chemical redox reactions between the 2 electrodes.
• The nano-carbon materials increase the surface of the electrodes and hence increase the capacitance, allowing them to store as much energy as traditional lithium battery cells.
• Fault-tolerant, resilient power pack batteries. The powerpack is created by connecting the capacitors in a small grid mesh. If for some reason a cell becomes defective (e.g. because it is damaged), then the electrolyte that doesn’t get soaked up by the carbon material might leak out and will evaporate. As no dendrites can form to create a short circuit between the electrodes, the above failure mode becomes an open circuit and while the power pack will lose some capacitance, it will continue to function as a battery.
• No dramatic warming up as each cell has a low internal resistance and in combination with the meshing connections, a power capacitor pack warms up very little even when high currents are used.
• Destructive tests have demonstrated the safety of the cells: hard short-circuit, overcharging, forced discharging, fire, drop test, nail puncture (internal short circuit), and even shooting on it with a gun showed no fire and no explosion.
• Our stress and abuse tests have demonstrated extreme robustness. Even when subjected to load conditions way beyond the permissible values, the cell keeps functioning.  See some results at https://kurt.energy/unparalleled-robustness-of-blue-cell-power-capacitors/

Besides the safety and reliability benefits using power capacitors also translates into a simpler system design. Firstly, a BMS (Battery Management System) is needed to actively balance the cells when charging or discharging but mostly only long-term. A failing BMS is often a root cause of a battery fire. Secondly, as the cells can operate from very cold freezing temperatures to very warm desert-like temperatures, most or no active cooling is needed as the cells barely warm up. Hence, most of the space is occupied by the cells and not by supporting subsystems.

While we currently mostly sell custom-made power capacitor battery packs, production licenses can be negotiated.

The interested reader can find a very detailed overview of battery safety issues in the excellent special article of Best Magazine UK (url: https://www.bestmag.co.uk/emags/BESTMAG65-Summer2019/?page=39

A relevant extract can be downloaded here: BestMagAug2019 safety extract

And while researchers are still debating how hybrid supercapacitors really work, there is now a growing consensus that there is a continuous spectrum of mechanisms between pure battery behavior (good for energy storage) and capacitative behavior (good for power, safety en many more desirable properties). Meanwhile, we put hybrid supercapacitors at work since many years! For the interested reader:

https://drexel.edu/news/archive/2022/March/battery-capacitor-electrochemical-energy-storage-spectrum

Using clean electric energy has always been hampered by the limitations of how to save and store it in batteries, how to use the energy from it and especially on how to charge these batteries. With Carbon-based Power Capacitors many applications become practical again and they enable us to reach clean energy sustainability as never before.