Layered Carbon Nanotube Architecture for High Power Lithium Ion Batteries

A. Shah, M.N. Ates, S. Kotz, J. Seo, K.M. Abraham, S. Somu, A. Busnaina
Center for High-rate Nanomanufacturing, US

Keywords: carbon nanotubes, Li-ion battery

Summary:

To address these limitations for high-power Li-ion batteries, we have developed a novel multi-layered electrode architecture consisting of alternating layers of carbon nanotubes and lithium ion active materials stacked on a current collector. A highly conductive and porous matrix is achieved through these intermittent layers of carbon nanotubes facilitating electron transport and lithium ion diffusion throughout the electrode thus enhancing bulk conductivity of the electrode. Micron-sized spinel lithium manganese oxide (LiMn2O4) and multi-walled carbon nanotubes (MWNT) are used in these electrode architectures. We demonstrate a significant increase in power density of a lithium ion cathode with high active material loading in the range of 8-10mg/cm2 and low carbon contents of 10% and 20%. At high discharge rate of 10C, a multi-layered electrode containing a high active material loading of 9 mg/cm2 demonstrates greater than 65% capacity retention and highly stable cycling for over 100 cycles while conventionally prepared electrode exhibits less than 10% capacity retention at loading of 2 mg/cm2. These values translate to an enhancement in power density by 20 times over a conventionally prepared cathode of identical composition. We also demonstrate improvement in volumetric density by a factor of 3 over a conventionally prepared electrode.