The Supercapacitor Advantage

Each day brings a new technical innovations, and the demand for smaller, more portable and more functional electronics. This puts pressure on power supplies to be light and small, run for long periods of time (i.e., have lots of energy), and meet the demands of multiple high current loads (i.e., have a high power capability). Simply put, these demands cannot be met by any one portable power supply.

For decades, batteries have been the preferred storage device for portable electronics, mainly because of their ability to store energy (high energy density). But batteries take a long time to discharge and recharge, which limits their ability to deliver power. Overcoming this power deficit is difficult, if not impossible, and even newer battery technologies such as lithium ion are still a poor solution for high power applications. In applications demanding high power, over-engineering the battery will rarely be the right solution, and will typically result in increased size, weight, and cost, and/or reduced cycle life and energy. In other words, a magic bullet is hard to find.

This power deficit is being stretched further by the explosion in the Internet of Things (IoT). These applications are usually wireless-enabled, and yet they demand ever smaller and more portable devices, with more features and functions. Wireless transmissions, even over very short distances, present a tremendous power challenge to the necessarily small batteries being used in IoT devices.

CAP-XX believes that supercapacitors will be a critical enabling technology for the IoT, offering a unique combination of high power and high energy, in a thin, flat and very small package, to improve battery performance, and in some cases, when used with an ambient energy harvesting module or rapid recharge system, replacing the need to use a battery at all.

What Makes Supercapacitors Super?
Supercapacitors combine the energy storage properties of batteries with the power discharge characteristics of capacitors.

To achieve their energy density, they contain electrodes composed of very high surface area activated carbon, with a molecule-thin layer of electrolyte. Since the amount of energy able to be stored in a capacitor is proportional to the surface area of the electrode, and inversely proportional to the gap between the electrode and the electrolyte, supercapacitors have an extremely high energy density. They are therefore able to hold a very high electrical charge.

The high power density derives from the fact that the energy is stored as a static charge. Unlike a battery, there is no chemical reaction required to charge or discharge a supercapacitor, so it can be charged and discharged very quickly (milliseconds to seconds). Similarly, and again unlike a battery, because there are no chemical reactions going on, the charge-discharge cycle life of a supercapacitor is almost unlimited.

Supercapacitor Characteristics

• Charge/Discharge Time: Milliseconds to seconds
• Operating Temperature: -40°C to +85C°
• Operating Voltage: Aqueous electrolytes ~1V; Organic electrolytes 2 – 3V
• Capacitance: 1mF to >10,000F
• Operating Life: 5,000 to 50,000 hrs (a function of temperature and voltage)
• Power Density: 0.01 to 10 kW/kg
• Energy Density: 0.05 to 10 Wh/kg
• Pulse Load: 0.1 to 100A
• Pollution Potential: No heavy metals

Supercapacitor Advantages

• Provide peak power and backup power
• Extend battery run time and battery life
• Reduce battery size, weight and cost
• Enable low/high temperature operation
• Improve load balancing when used in parallel with a battery
• Provide energy storage and source balancing when used with energy harvesters
• Cut pulse current noise
• Lessen RF noise by eliminating DC/DC
• Minimise space requirements
• Meet environmental standards