Testing of Carbonaceous Nanomaterials for Improved Lithium Ion Battery Anodes

Fossil fuels are our major source of energy, but they are depleting quickly. They also create major environmental issues such as climate change by causing the emission of carbon dioxide and other greenhouse gases. As a result, clean and renewable sources of energy such as solar, nuclear and wind are being considered as alternatives to fossil fuels. Some renewable energy sources are intermittent such as solar and wind requiring large scale energy storage to make them practical. Also, for applications in portable electronics and vehicles, the energy storage devices need to be small, safe and light. Rechargeable batteries have the potential to meet these requirements. In particular, lithium ion batteries currently outperform all other rechargeable battery systems due to their high energy density and design flexibility. In our laboratory, we create lithium ion battery coin cells for testing a variety of novel electrode materials. Due to the sensitivity of the lithium ion battery materials to oxygen, nitrogen and water, batteries are fabricated in a glove box filled with argon. These cells are then taken out of the glove box to be electrically tested using the battery testing system. The new battery testing system enables us to test and analyze the most important battery parameters. First, we can measure the energy density and charge capacity, which directly depend on the electrode materials. Second, we measure how the charge capacity changes as the batteries are cycled, which is crucial to the applicability of this technology in durable goods such as vehicles. Furthermore, this battery testing system has the advantage of having 32 completely independent channels that enable us to test 32 lithium ion batteries simultaneously and with great precision. Testing parameters such as charge/discharge rate and voltage and current ramps can be controlled independently for each channel. To fully test a battery can take weeks or months depending on the charge/discharge rate making the ability to test a large number of batteries simultaneously key to efficient research. In our laboratory, we specifically investigate the properties of carbon nanomaterials such as Single-Walled Carbon Nanotubes (SWCNT) and graphene for applications in Li-ion battery electrodes. While the properties of SWCNTs have been investigated previously as anodes in lithium ion batteries, these results have been difficult to interpret and the anode performance has likely not been optimized due to the polydispersity in structure and electronic properties of the as-synthesized SWCNT material. To address this limitation, we …