Nanotube Arrays for Advanced Lithium-ion Batteries
The development of high-power, high-energy, long-life, and low-cost rechargeable batteries is critical for the next-generation electric and hybrid electric vehicles. Among various battery technologies, lithium-ion batteries (LIBs) are promising energy storage devices as a result of the high energy densities, low self-discharges, and long cycle lives of known LIBs. Market analysis projects that the LIB market will increase to over $77 billion within the energy storage, electric vehicles, and mobile IT industries by 2020. The growing market segments are searching for battery technology that can increase the power and energy densities as well as provide a higher cycle count.
Three basic functional elements support the electrochemical reactions in a lithium ion battery. These elements are anode, cathode, and electrolyte. Both the anode and cathode are materials which lithium ions can migrate. The process of lithium moving into the anode or cathode is referred to as insertion (or intercalation), and the reverse process is referred to as extraction (or deintercalation). When a cell is discharging, the lithium ions are extracted from the anode and inserted into the cathode. When the cell is charging, the reverse process occurs: lithium ions are extracted from the cathode and inserted into the anode.
NREL scientists have oriented arrays of metal oxide nanotubes (NTs) aligned perpendicular to the current-collecting substrate through a low-cost electrochemical anodization technique. The oriented nanostructured electrode materials offer significant advantages over both conventional microstructured and more recent disordered nanostructured electrode materials.Description
NREL scientists have come up with novel electrode architecture for increasing the charge rate, cycle count and overall energy density. This is achieved by orienting arrays of nanotubes (NTs) such that they are aligned perpendicular to the current-collecting substrate. These arrays increase the overall surface area, which provide additional lithium storage capacity. Unlike most nanostructured lithium storage electrodes, which are based on randomly packed disordered materials and limit a battery’s power and energy density, NREL’s arrays are structured in a systematic and organized fashion.
These NT arrays are oriented in a linear arrangement of pores that provide direct conducting pathways for electrons and ions, allowing for faster ion and electron transport. This invention covers the electrochemical syntheses of the oriented NT electrodes with various metal oxides and the influence of nanostructure parameters (e.g., wall thicknesses, pore diameters, inter-tube spacings, film thicknesses, crystal phases) on the electrode performance (eg, capacity, lithium insertion/extraction potentials, electron and ion transport, solid-state lithium diffusion time constant, and charge/discharge rates).
NREL scientists have demonstrated the additional benefits from this electrode architecture. This technology is ready to undergo continual development and commercialization.Benefits
- Faster charge/discharge rates (higher power density)
- Higher structure stability (increased cycle count)
- Larger surface area leading to increase capacity (higher energy density).
- Li-ion batteries
- Energy storage
- Electric vehicles
|Title and Abstract||
Oriented nanotube electrodes for lithium ion batteries and supercapacitors
An electrode having an oriented array of multiple nanotubes is disclosed. Individual nanotubes have a lengthwise inner pore defined by interior tube walls which extends at least partially through the length of the nanotube. The nanotubes of the array may be oriented according to any identifiable pattern. Also disclosed is a device featuring an electrode and methods of fabrication.
|National Renewable Energy Laboratory||03/05/2013
|Technology ID||Development Stage||Availability||Published||Last Updated|
|NREL ROI 08-01||Prototype||Available||03/04/2013||01/31/2013|