Nanohybrid Carbonaceous Materials for Energy Storage Systems

This paper introduces a viable alternative to electrically conductive carbonaceous materials for a variety of energy storage systems. Novel “nanohybrid” particles have been created by in situ synthesis of carbon nanotubes (CNTs) on graphite particles. The nanohybrid structure of the materials reported in this paper is comprised of 5-micron natural crystalline flake graphite particles that are densely carpeted with multiwall CNTs. Such nanohybrid particles are capable of providing a greater level of electrical conductivity in electrode matrices than any known synthetic or classic natural graphite. The nanohybrid particles also have a significantly higher specific surface area (> 3X) vs. the graphite particles alone. The nanohybrid particles are also thermally purified to achieve carbon purity > 99.9999%. The combination of ultra-high purity, high surface area, and high electrical conductivity makes this new category of electrically conductive carbonaceous material an attractive candidate for application as a next-generation conductive additive in both anodes and cathodes of lithium-ion batteries. Additionally, this material is expected to find use in the composition of the negative expander paste of start-stop lead-acid batteries. It can also be used as a pigment in a variety of electrically conductive coatings for batteries, EMI shielding, and other specialty applications. This nanohybrid technology can be implemented in both portable, as well as stationary energy storage systems, including electric vehicles, mobile power devices, power tools, solar power generation, backup and off-grid power, and utilities. In this paper, the structure and properties of this novel nanohybrid material system will be reviewed. In addition, preliminary test data for lithium-ion batteries and lead-acid batteries incorporating these nanohybrid materials in the electrodes will be presented.