The GC Lithium-ion Capacitor has the highest energy density of any commercial ultracapacitor
What is a Lithium-ion Capacitor?
A Lithium-ion Capacitor is an electrochemical capacitor that combines the ion intercalation mechanism of a lithium-ion battery with the cathode composition of an electric double-layer capacitor, aka supercapacitor. This hybrid configuration allows the LiC to have superior energy density compared to supercapacitors and increased power density, safety, and charging efficiency compared to batteries.
The graphic above shows the basic structure of the LIC cell. Three main components include: positive activated carbon cathodes, negative pre-lithiated anodes, and separator membrane.
Batteries, supercapacitors (also known as EDLCs), and LiCs all have unique properties which make them suitable for specific applications. The LiC has higher power, longer cycle life, and are safer to use than batteries. LiCs also have a higher voltage and much more energy density than EDLCs. Since LiCs combine both high energy density and high power density, they can improve efficiency and enhance power of electrical systems by replacing existing energy storage technologies, including both EDLCs and batteries.
The novel configuration of the LiC cell is comprised of activated carbon cathodes and graphite anodes that are pre-lithiated by a patented process. The lithiated anode lowers the charge potential and results in an overall higher cell voltage. The GC Li-ion Capacitor uses high-performance electrodes that increase capacitance and lower internal resistance. LiC manufacturing is environmentally-friendly and doesn't create toxic byproducts.
Rechargeable batteries aren't as efficient as LiCs at sustaining large electrical loads because discharging creates a "memory effect" that quickly diminishes its capacity over time. Most batteries can only perform around 500-1000 charge cycles before they become depleted- this is why a car or cell phone battery must be replaced every few years. However, GC LiCs can perform over 250,000 discharge cycles. This equates to many more years of operation, less maintenance, and reduced cost of ownership.
GC Li-ion Capacitor cells are tested for capacitance, internal resistance, cycle life, and temperature range using the same performance metrics as industry-leading ultracapacitor manufacturers. This includes a high temperature, high voltage DC-life test. In this test, the cell is discharged at 3.8 V floating voltage for over 2000 continuous hours in a 65° C heat environment.
LiCs are also tested for low self-discharge rate, averaging only a 5% voltage drop from maximum charge over a three month period compared to EDLCs- which can lose up to 50% in a single month.