Why do you need a Lithium-ion Capacitor?

When designing electronic applications the energy household is one of the puzzles that needs to be solved. Topics like energy storage, power consumption and peak power needs need to be addressed. With the increased focus on energy consumption and energy efficiency this is becoming an even bigger challenge. A battery is often used for long-term energy storage and a capacitor for short-term energy storage. Both have their advantages and their limitations. Jianghai is now introducing lithium-ion capacitors as a third option that fits between the use of a battery and a regular capacitor. 
An advantage of lithium-ion capacitors over batteries comes into play when higher temperatures are involved. Lithium-ion capacitors and batteries are both very stable in room temperature where both technologies discharge less than 5% over hours. But at 60°C a battery loses 30% of its capacity over the same time and a lithium-ion capacitor will stay below 15% discharge. 
A second advantage is that with lithium-ion capacitors you don&#;t need to worry about the risk of thermal runaway. A lithium-ion capacitor dos not use metallic lithium or lithium oxide. 

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Other features and advantages of Lithium-ion Capacitors are:

• > charge cycles
• Broad temperature range
• Low weight
• Quick charge and discharge times
• High pulse current

Typical applications include:

• E-Mobility
• Energy storage / energy backup
• Smart metering
• Power tools
• Automated guided vehicles
• Industrial truck & city busses

What can we offer?

Jianghai offers a broad range of lithium-ion based solutions to cover many application requirements. This includes radial components with a capacity range starting at 30F up to 220F. Pouches are also available in range 1.000F up to 16.000F or even more when pouches are combined. The lithium-ion capacitors can be used in new designs and can optimize existing designs by replacing the current energy storage components.
Please do contact us with your requirements &#; we are happy to help and advice the right part(s). With the capacitor pouches we can configure a capacity pack that can replace an entire battery pack or that can be used in combination with  battery pack, for instance to handle peak load in high power applications. Both voltage and capacitance can be configured on your specification. The capacity packs can be delivered with and without a cell management system (or capacitance management system, CMS) to balance the individual cells. 

An example application Jianghai developed is a product assembly using radial LIC's that delivers 12V/1A for 30 seconds. This product is used as a mini-backup power module. The end customer uses this module in a payment device. The 30 seconds gives the customer time to finish a payment and power a large LCD display. The module consists of a CMS and 3 or 6 LI-capacitors in different configurations for 12V and 24V.  

For more information, please visit SUNJ ENERGY.

Figure 7(a) shows the SEM image of AC anode, which shows irregular structure and occupies the vast majority of space. Meanwhile, SP uniformly dispersed between gaps of AC particles can provide good conductivity. Figure 7(b) shows the SEM image of graphite cathode, and Figure 7(c) shows the SEM image of MWCNTs/graphite composite cathode; comparison shows that MWCNTs and graphite are well connected and present a web-like network structure and three-dimensional conduction system. This structure was applied to the negative electrode to shorten the diffusion path of lithium ions and improve the kinetics of lithium-ion intercalation.

4.2.2 Galvanostatic charge and discharge

Figure 8(a) shows the first charge and discharge curves of raw MWCNTs and graphite half-cells at 1C rate; for graphite half-cells, the voltage plateau of SEI film formation is at about 0.7 V [36]. In comparison, for MWCNT half-cells, the voltage plateau of SEI film formation is at about 0.7 V too. Meanwhile, MWCNTs have a higher irreversible capacity and first discharge capacity than graphite. Figure 8(b) shows the differential capacity versus voltage (dQ/dV) curves of MWCNTs and graphite half-cells. Three stages of lithium-ion intercalation voltage were local on 0.16, 0.08, and 0.055 V, respectively. Figure 8(c) shows the first delithiation (charge) capacity of CNT0, CNT25, CNT50, CNT75, and CNT100 at 60 min prelithiation time. In the same prelithiation time, the open-circuit voltage (OCV) of pure graphite half-cell was significantly superior to other half-cells. The delithiation capacity increases with the gradual increase of MWCNTs, which indicates the kinetics of intercalation of MWCNTs is higher than pure graphite.

Figure 9(a&#;e) showed the galvanostatic charge-discharge curves of LIC0, LIC25, LIC50, LIC75, and LIC100 at different current densities, respectively. The tests were performed using two-electrode system at voltage profile of 2&#;4 V. The energy density of LICs can be calculated by Esp = (Csp*V2)/2 (Csp represents the specific capacitance and V represents the discharge potential excluding IR drop). The power density of LICs can be calculated by Psp = Esp/t (t represents the discharge time), and the specific capacitance Csp can be calculated by the formula C = (2I*t)/(m*ΔV) (I represents the discharge current, m is the active material mass of a single pole, ΔV is the potential of discharge, and t is the discharge time). The charge-discharge curves of LIC25 showed a good linear relationship and exhibited a shape of isosceles triangle. The LIC25 had the longest discharge time than other LICs and showed good capacitance characteristics. Meanwhile, the charge-discharge curves of LIC75 also showed a good linear relationship and exhibited high power performance. On the contrary, the charge-discharge curves of LIC0 and LIC100 presented a distorted shape, and the internal resistance obviously increases with the improving current density and the discharge time is obviously shortened, which related a poor power density. Generally, the power density of LICs is determined by the negative materials; when the negative electrode consists of pure graphite, the rate of intercalation and deintercalation of lithium ions is slow, resulting in a poor power density. The intercalation and deintercalation rate of lithium ions will be accelerated with the addition of MWCNTs. However, excessive amounts of carbon nanotubes will consume large amounts of lithium ions, and the formation of thick solid electrolyte interface (SEI) film will greatly impede the migration of lithium ions. That is, the appropriate MWCNTs content to improve the power density is of crucial importance.

Figure 9(f) showed the specific capacitance of LICs at various current densities. The LIC25 showed higher discharging specific capacitance and rate performance than other LICs. Figure 9(g) showed the ragone plots of LICs. LIC25 presented the best electrochemical performance. The maximal energy density and power density of LIC25 reached 96 Wh/kg and 10.1 kW/kg in the range of current density from 0.1 to 8 A/g.

Figure 10 showed the charge and discharge cycle performance of LIC0 and LIC25. The  cycles test was performed in the range of 2.2~3.8 V at the current density of 0.8 A/g. After  cycles of constant current charge and discharge, the cycling performance of LIC0 drops significantly, which is related to the cracking and pulverization of graphite materials, lithium, and organic solvents common into the graphite layer, and then influences the performance of cycle. As opposed to LIC0, the capacitance retention of LIC25 still holds 86%, the charge and discharge curves without twist and distortion, which still maintained a good isosceles triangle shape and shows good cycle performance.

The company is the world’s best lithium ion capacitor supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.