Unleashing the Power of Lithium-Ion Capacitor: A Comprehensive Guide

Lithium-ion Capacitor

Lithium Ion Capacitor Overview

Lithium-ion capacitor is a new type of energy storage device between electric double layer capacitors and lithium-ion batteries. They have the characteristics of high energy density, ultra-high power density, long cycle life, large current charge and discharge, and wide operating temperature range. , can be widely used in electric vehicles, new energy power generation, rail transportation, national defense industry, aerospace and other fields, and is a research hotspot in the field of new energy.

The Birth and Development of Lithium-ion Capacitors

  • Early capacitor technology

Traditional capacitors have been used for decades as devices for quickly storing and releasing electrical energy. They consist of two conductive plates separated by an insulating material (dielectric). Capacitors store energy by maintaining a potential difference between the plates.

  • Introduction to supercapacitor

Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are improvements over traditional capacitors. They use high surface area porous materials as electrolytes, allowing for higher energy density compared to traditional capacitors. Compared to batteries, supercapacitors can provide higher power but have lower energy density.

  • Development of lithium-ion batteries

The development of lithium-ion batteries has revolutionized portable electronics and electric vehicles. Lithium-ion batteries use lithium ions as charge carriers and have higher energy density than traditional batteries.

  • The combination of capacitors and batteries – the birth of li-ion capacitor

Researchers are trying to combine the advantages of capacitors and lithium-ion batteries to create hybrid energy storage devices. Lithium-ion capacitors were born out of this effort. They typically consist of carbon-based electrodes (similar to supercapacitors) and lithium-ion intercalated electrodes (similar to lithium-ion batteries).

  • Advantages of li-ion capacitor

Lithium-ion capacitors have high power density, allowing for fast charging and discharging. They also offer higher energy density than traditional capacitors, making them suitable for applications where the balance between power and energy is critical.

Classification of Lithium-ion Capacitors

Lithium-ion capacitors (LICs) can be classified based on their specific design and operating principle. The two main types of lithium-ion capacitors are hybrid capacitors and asymmetric capacitors:

  • Hybrid Capacitor

Hybrid capacitors combine the properties of electric double layer capacitors (EDLC or supercapacitors) and lithium-ion batteries. They usually consist of carbon-based electrodes and lithium-ion intercalation electrodes for electric double layer capacitors. Carbon electrodes provide high power density, allowing rapid charging and discharging, while lithium-ion embedded electrodes help increase energy density.

  • Asymmetric Capacitor

Asymmetric capacitors, also known as composite capacitors or asymmetric hybrid capacitors, have electrodes with different charge storage mechanisms. Typically, one electrode is primarily used as a supercapacitor (electric double layer capacitor), while the other electrode is used as a lithium-ion battery electrode. This design allows for a synergistic combination of high power on the supercapacitor side and higher energy storage on the lithium-ion battery side.

Both hybrid and asymmetric capacitors aim to strike a balance between the high power density of supercapacitors and the higher energy density of lithium-ion batteries. The specific classification may vary based on the electrode material, electrolyte, and overall design of the lithium-ion capacitor.

Working Principle of Lithium-ion Capacitor

The positive electrode material of lithium ion capacitor is an activated carbon material with double electric layer energy storage, the negative electrode material is an intercalated carbon material with lithium ion deintercalation function, and the electrolyte is lithium salt electrolyte. When the battery is charging, lithium ions leave the surface of the cathode material, pass through the electrolyte and separator, and are inserted into the lattice of the anode material; when discharging, lithium ions escape from the lattice of the anode material and return to the cathode material through the electrolyte. The surface forms an electric double layer with the positive charge. The negative electrode potential after lithium embedding is low, and has the characteristics of high operating voltage, energy density and power density between lithium-ion batteries and supercapacitors.

Working Principle of Lithium-ion Capacitor

Characteristics of lithium ion capacitor

Lithium-ion capacitors are hybrid capacitors that combine the two advantages of supercapacitors and lithium batteries: the “long life” of an electric double layer capacitor that can be repeatedly charged and discharged, and the “high capacity density” of lithium-ion secondary batteries. This ionic capacitor uses technology that pre-dopes lithium ions on the negative electrode and can be used at a low voltage of 3.8V. In addition, it does not contain heavy metals that can pollute the environment and is an environmentally friendly capacitor.

Extremely high high temperature reliability and safety are the outstanding features of lithium-ion capacitors.

High-temperature reliability that can be used in an environment of 85°C, and superior high-temperature load characteristics compared to electric double layer capacitors. Please refer to the following characteristic diagram:

Lithium-ion capacitors are highly safe as they are made of materials that are not prone to fire.

Compared with lithium-ion secondary batteries, thermal runaway is less likely to occur, ensuring safety.

Lithium-ion capacitors discharge little themselves and can also be used as standby power supplies for machines. Please refer to the following characteristic diagram:

Lithium-ion capacitor

Comparison of lithium-ion capacitors, supercapacitors and lithium-ion batteries

Lithium-ion capacitors are hybrid capacitors that combine the long life of electric double layer capacitors and the high capacity density of lithium-ion secondary batteries into one. The following figure is a comparison chart between them:

Supercapacitor Lithium-ion Capacitor Lithium-ion Battery
Operating Temperature Range -20~+70℃ -20~+85℃ -20~+60℃
Electrode Material Activated carbon Activated carbon

Carbon-based materials

Li metal oxide

Carbon-based materials

Electrolyte Organic solvents Organic solvents Organic solvents
Electricity Storage Method Utilizing the naturally occurring electrical double layer Doping and dedoping using the electric double layer and ions Utilize redox reactions
Public Hazard None None None
Charge and Discharge Times More than 100,000 times More than 100,000 times More than 100,0 times
Electrostatic Capacity Per Unit Volume(※) 1 2 100

※Comparison when electric double layer capacitor is 1

Lithium-ion capacitor application cases

  • In low-power systems, the previous secondary battery is replaced with a li-ion capacitor.

Lithium-ion capacitor has large capacity and low self-discharge current. When combined with solar panels, these characteristics can be used to replace the previous secondary battery with lithium-ion capacitor. It requires no maintenance for 10 years and can reduce replacement costs. Secondary batteries need to be replaced every few years.

  • Applications in machine instantaneous shutdown and backup power supply

Lithium-ion capacitor

For equipment such as manufacturing equipment and medical equipment, even a momentary voltage drop can cause fatal injuries. Utilizing the extremely high high-temperature reliability of lithium-ion capacitor, which can be used in small spaces with heat sources, lithium-ion capacitor can be used as dispersed and selective backup power supplies and auxiliary power supplies (such as for uneven voltage on solar panels). It can be supplemented as a server (CPU, DRAM, RAID controller, SSD and other components, backup power supply when the machine is stopped, etc.). In addition, from the perspective of power storage, it can be used as regenerative energy for cars, trucks, and elevators. It can also be used in storage motors for solar power generation.

Conclusion

Lithium-ion capacitors are a new type of electrochemical energy storage device. They have higher energy density than electric double layer capacitors, higher power density and longer cycle life than lithium-ion batteries. In addition, they also have high safety features. , has huge application value and market potential in many fields such as electric vehicles, hybrid vehicles, electricity, rail transit, communications, national defense, consumer electronics, etc.