Development of Lithium-ion Capacitors for Hybrid Vehicles (Part 2)

Cost reduction by making modules③

Low price is important for expanding the market. However, it is not only required to reduce the price of power storage components, but also to comprehensively consider factors such as the installation environment and life of the power storage system to reduce the cost of the entire system.

Large power storage components are not products that can be good as long as they are cheap. Their long-term reliability is very important. Once a problem occurs, the market will lose trust and eventually cause huge losses.

Under actual usage conditions, they are not used as single units, but need to be made into modules to ensure a given voltage or output power, so the cost of modules must be reduced.

LIC can reduce module costs from the following three points: ① The voltage of the single unit is higher, which can reduce the number of units; ② Excellent high-temperature durability, relatively loose installation conditions; ③ It can reduce management costs.

Regarding ①, when making a module of a given voltage, the higher the unit voltage, the fewer units are used. For example, when the voltage is 300V, 120 2.5V units of EDLC are required, while only 80 3.8V units using LIC are required.

Due to the characteristics of ②, it can be used under a wider range of temperature conditions. When very strict temperature management is required like LIB, the installation location will be limited. However, if the high-temperature durability is excellent, the restrictions on the temperature environment can be relaxed, so the degree of freedom of the installation location is higher, which can contribute to cost reduction.

The management cost of ③ refers to the cost related to the management system "Battery Management System (BMS)" of the storage component. The charge and discharge curves of rechargeable batteries such as LIBs will change greatly with the current value and temperature environment, so BMS will cost money to manage the charging state.

As shown in Figure 3, the slope of the charge and discharge curve of LIC does not change significantly with the current value. This trend does not change with temperature either, and the charging state can be grasped by managing the voltage, so the cost of BMS can be reduced.

Figure 3: LIC that makes it easy to manage the charging state even when the current value changes. LIC makes it easy to manage the charging state of the cell because its slope does not change even when the current value during input and output changes significantly.

The power recycling market accounts for more than half of LIC's market

The above introduces the general characteristics of LIC. Next, we will introduce the characteristics of the LIC we developed, EneCapTen (Figure 4). The EneCapTen unit adopts a laminated structure that emphasizes heat dissipation, and can charge and discharge large amounts of power. The life span is extremely long, reaching more than 100,000 times. In addition, considering the environmental impact, no heavy metals such as lead are used.

Figure 4: The LIC “EneCapTen” unit developed by FDK adopts a laminated structure (a). The 45V module consists of 12 units (b).

The modules will be designed according to the user's performance parameters. In addition, the general modules shown in Table 2 are now available, and the 4000F unit for hybrid vehicles is now under development.


At present, the main uses of LIC are the following four aspects: ① Backup market such as instantaneous voltage drop compensation devices and UPS (uninterruptible power supply); ② Power regeneration market such as hybrid vehicles, cranes and construction machinery; ③ Load leveling market such as solar power generation and wind power generation; ④ Power auxiliary market such as hybrid vehicles and copiers.

Among them, the power regeneration market has the largest market size, which is estimated to account for more than half. However, it is expected that with the expansion of the smart grid field in the future, load leveling uses such as solar power generation and wind power generation will also form a huge market.