Application of exfoliated synthetic graphene for Lithium-Ion secondary battery

To improve the load characteristics of lithium-ion secondary batteries, a carbon material is used as the conductive additive in the positive as well as negative electrodes. To increase the capacity of the secondary battery, it is necessary to increase the capacity of the active anode material. Hence, studies on the use of silicon for the anode have been performed in various fields. In this context, we establish that the application of exfoliated graphene as the conductive additive is effective in improving the charge/discharge cycle characteristics compared to commonly used carbon materials, such as Ketjenblack and graphite. Exfoliated synthetic graphene produced using a biaxial, independently controlled three-dimensional rotary ball mill has a unique shape. In order to uniformly disperse it in the electrode, while maintaining a flake shape thinner than graphene, we developed a dispersion technology using a wet process that utilizes a homogenizer and a jet mill. Although the resistance component of the electrode synthesized by mixing exfoliated graphene with powdered silicon is greater than that of the other carbon materials, it is considered advantageous as a conductive additive because it ensures physical contact with the active material, even when the anode matrix disintegrates due to the rapid volume changes in silicon caused by repeated charge/discharge cycles. Copyright © 2021 The Japan Institute of Electronics Packaging.