New Technology InsightsVGCFTM-H: Conductive additive for cathode/anode of LIB

Following the spread of electric vehicles (EVs) and energy storage systems (ESS), the large Li-ion battery (LIB) market is expected to grow substantially in the future. A large LIB has various characteristic requirements in terms of temperature, resistance, and life, resulting in its materials constantly evolving. VGCFTM-H: our conductive additive for the cathode and anode of LIB is effective in improving several types of performance including durability at high temperatures, charge/discharge performance at low temperatures, and suppression of the rise in the internal resistance, even in the environments of the latest materials.

What is VGCFTM-H?

Basic Physical Properties of VGCFTM-H
Average fiber diameter 150 nm
Average fiber length 6 μm
Specific surface area 13 m2/g
Powder resistivity 0.015 Ω・cm
Carbon content 99.99wt%

This material is fibrous graphite synthesized by the vapor phase method. Thick and rigid fibers form conductive paths between active materials, and their holes assist the penetration of an electrolyte into electrodes, both of which improve input/output and low-temperature characteristics of a LIB. Controlling specific surface area by heat treatment mitigates degradation and enhances safety in high-temperature environments. Over the 15 years since its release, VGCFTM-H has been the only material that improves several characteristics of a LIB, where usually there are tradeoffs.

In response to the expansion of their applications, the characteristic requirements of LIBs have been increasing in variation and complexity, which results in their materials constantly evolving. We have confirmed that VGCFTM-H further capitalize on its features even in the material configurations of current trend.

Basic properties

Improving rate properties and low-temperature characteristics

When a LIB is charged or discharged, lithium ions move between the particles of the active materials. With the recent needs for higher-capacity batteries, the electrode density has been increasing. On the downside, the gaps through which the electrolyte penetrates when the electrodes are pressed together become smaller, hampering efficient ion transfer. VGCFTM-H entering between active materials prevents the gaps between the electrodes from being completely crushed during the pressing of the electrodes, allowing smooth movement of lithium ions. As a result, the rate properties at room temperature are improved, which enables fast charging. VGCFTM-H also suppresses performance degradation at low temperature environment, which raise the viscosity of the electrolyte and makes it difficult for the ions to move. When used for the anode, it suppresses lithium precipitation and prevents a short circuit, contributing to enhancing the safety of the battery.

Maintaining the high-temperature resistance & preventing battery swelling

For responding to the performance demands for severe travelling environments of EVs, superior storage characteristics and resistance to degradation at high temperatures are required for LIBs. Electrode materials with large surface areas are easy to react with the electrolyte, which degrades battery performance. Therefore, a conductive additive, which is an additive to the electrolyte, should have a small surface area.
With our proprietary technology, VGCFTM-H has a small surface area, which contributes to maintaining the storage characteristics and degradation resistance of a battery at high temperatures. When used in the anode, it suppresses the generation of gasses originating from reduction of components, which prevents the swelling of the battery.

Conductive paths contributing to the extension of battery life

For LIB electrodes, electrically conductive materials that connect active material are required to efficiently transmit the generated electricity. However, expansion and shrinkage of active materials due to repeated charging and discharging increase the distance between active materials and raises the resistance hampering electrical conduction. Having a long straight fiber shape, VGCFTM-H becomes conductive paths between the particles of the active material. It prevents a rise in electrical resistance after repeated expansion and shrinkage, which extends battery life.

Download the Technical Article,
(Here for measurement results)

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