Electrochemical Capacitors
Overview
Electrochemical capacitors (ECs) have been an important development in recent years in the field of energy storage. These devices operate between rechargeable batteries and electrolytic capacitors with respect to energy and power performance. Electrochemical capacitors differ from batteries in that they do not store energy in redox reactions that occur in the electrode structure. Electrochemical capacitors store energy through electrostatic interactions that occur in the electrode and solution interface region, also known as the double layer. Ionix manufactures a variety of cell designs and configurations for high reliability applications. Please contact us for more information concerning our products.
| Performance Characteristics of Energy Storage Technologies | |||
| Performance Parameter | Lead Acid Battery | Ultracapacitor | Conventional Capacitor |
| Charge Time | 1 to 5 hours | 0.3 to 30 seconds | 10-3 to 10-6 seconds |
| Discharge Time | 0.3 to 3 hours | 0.3 to 30 seconds | 10-3 to 10-6 seconds |
| Energy Density (Wh/kg) | 10 to 100 | 1 to 10 | < 0.1 |
| Cycle Life | 1,000 | > 500,000 | > 500,000 |
| Specific Power (W/kg) | > 100 | > 1,000 | > 10,000 |
| Charge/Discharge Efficiency | 70% to 85% | 85% to 98% | > 95% |
A key advantage of this technology is the reversible nature of this process. As a result, an electrochemical capacitor can be charged and discharged hundred of thousands of times in comparison to batteries, which can only withstand thousands of discharge cycles. At Ionix we are developing advanced materials that improve the performance of these emerging devices. In addition to their unique combination of power and energy and their high cycle life there are a host of additional characteristics that make electrochemical capacitor attractive in a variety of applications. These characteristics are outlined in the table below.
| Primary Characteristics | Secondary Characteristics |
| • High Power Density | • Long Life Cycle (Greater than 100,000) |
| - Competitive with high power | • Excellent cold temperature performance (-45 °C) |
| rechargeable batteries | • Fast recharge capability |
| • High Energy Density | • Easily monitored state of charge |
| - Order of magnitude higher than | • Low cost base materials |
| electrolytic capacitors | • High cycling efficiency |
| • Leakage current is stable over life | |
| • Significant surge capability (2.7V) | |
| • No charge/discharge memory | |
| • High reliability |
There are many applications that can benefit from the unique combination of high reliability, power, and energy provided by electrochemical capacitor technology. Several applications have drawn considerable attention. These applications include: regenerative braking in hybrid vehicles, cold engine starting, load leveling PEM fuel cells, ride-through backup power systems, and digital electronic devices. Each one of these applications represents a multi-billion dollar opportunity, if the technology can be successfully commercialized.