Researchers propose to further the development of high power density layered-layered CNT/active materials based cathodes and anodes for Li-ion battery. This layered-layered nanomaterial based electrode architecture designed to be compatible with various Li-ion materials was developed using a room temperature and pressure processes. Coin cell battery prototypes in full as well as half-cell configuration were fabricated and tested. Preliminary results indicate that these electrode architectures can have very high power density at a fast charge/discharge rate and long cycle life.
This battery electrode technology may have a large economic impact by enabling the realization of low cost all electric (EV), plug-in hybrid electric (PHEV), hybrid electric vehicles (HEV) and renewable energy storage devices. It will also exhibit the advantages of incorporating nanotechnology into macroscopic devices. The layered-layered electrode technology is compatible with various types of active materials and can be readily incorporated into the existing manufacturing process, enabling the use of commercially available materials. This technology will aid researchers in understanding the impact of electrode architecture and geometry on the performance metrics for energy storage devices.
A low cost (>2Wh/$) lithium ion battery with very high energy (250 Wh/kg) and power density and long cycle life (14000 cycles; 20 years) can significantly enhance the possibility of overcoming cost and usage barriers associated with realizing high power Li–ion batteries for commercial applications. Currently employed rechargeable lead acid and nickel metal hydride batteries are costlier ($1300/kWh) and bulkier limiting their implementation. In addition the associated charge time can last for hours in some cases making them not suitable for practical use. The existing Li-ion batteries are hampered by employed electrode architectures and cannot provide such high power densities deteriorating at a fast rate leading to very short cycle life. Hence high power Li-ion batteries introduction into the market has been crippled. Currently, the need is satisfied with poorly performing heavy Ni-Cd batteries. Further more a quick charging battery with higher discharge rate at very high C rates is high desirable for any type of secondary charge storage device. The current market for high power density rechargeable battery for various applications is $3.8 billion and is projected to be $37 billion in 2020. While Li-ion battery holds 37% of the consumer electronics industry further enlargement of industry market share is hampered due to its inability to deliver high power density and the requirement for longer charge times. To address limitations of currently existing 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. Due to this employed layered electrode architecture the final battery volume can be reduced significantly (~4 times) thereby reducing the associated dead weight of the battery. In addition, the electrode architecture is fabricated in a cost effective manner by employing room temperature and pressure processes making it attractive for potential secondary energy storage applications. One of the goals of this project is to explore and systematically strategize commercial implementation of this developed technology. We found that through the I-Corps program that the developed technology would have an immediate impact on the unmanned vehicles segment, which requires sleek fast charging long life secondary lithium ion batteries. A new company "Nanopower solutions LLC" was founded in Nov 2013 to develop production of this novel electrode architecture for commercialization. We are actively engaged with the university in obtaining the patent rights. We are in contact with two Angel investors who are actively seeking to invest in this product. We expect this to happen in the next six months. Two papers were presented in conference and the patent filling has been extended to include Europe, china and South korea. Using micron-sized spinel lithium manganese oxide (LiMn2O4) and multi-walled carbon nanotubes (MWNT) in these electrode architectures, we demonstrated 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 a 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 the conventionally prepared electrode exhibits less than 10% capacity retention at a 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. This multi-layer structure when used in conjunction with a low-rate lithium ion cathode material, such as the high capacity lithium-rich lithium nickel manganese cobalt oxide, 0.3Li2MnO3 0.7LiMn0.333Ni0.333Co0.333O2 resulted in cycle life of greater than 500 full-depth cycles at a discharge rate of 1C. We identified improved porosity and conductivity of the intermittent carbon nanotube layer as the mechanism of performance enhancement from data obtained from galvanostatic cycling, electrochemical impedance spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and 4-point probe DC conductivity measurements. Our work exhibited the advantages of incorporating nanotechnology into macroscopic devices. Our layered-layered electrode technology is found to be compatible with various types of active materials and can be readily incorporated into the existing manufacturing process, enabling the use of commercially available materials. The outcome of the project aided us in understanding the impact of electrode architecture and geometry on the performance metrics for energy storage devices. Furthermore the commercialization methodology and pathways learned in the I-corps program encouraged other fellow faculty, graduate students and post-docs to explore labs to venture commercialization in their projects.
