Nanofilm Coatings Improve Battery Performance
TEM 2.5-nm-thick nano-coated ultrathin film on lithium-ion cathode particle surface; coating is highly uniform, in contrast to films applied through conventional technology (for reference, bar in lower-left corner measures 5 nm)
Comparison of cycling performances of Li-ion batteries made of LiNi1/3Co1/3Mn1/3O2 cathode powders with and withut (blue-colored) ultrathin-film Al2O3 nano-coatings: beter capacitance retention or cycling performance.
Recent advances in battery technology are expected to more than double consumer demand for electric vehicles within the next five years. The lithium-ion battery is an attractive candidate for use in such vehicles because of its light weight and high energy density. At present, however, lithium-ion batteries are not performing at the level desired. Lithium-ion batteries require even higher energy/power densities, longer lifetimes, and improved safety.
Some existing obstacles include the structural instability of electrode materials and the resulting rapid fade of cell capacity at high voltages and high temperatures. Scientists at Argonne National Laboratory have created an ultra-thin surface coating composed of metal oxides that, when applied to granular electrode materials on a large scale, promises to solve the problem of instability in lithium-ion batteries.Description
In developing a surface coating for the electrodes of lithium-ion batteries, Argonne scientists sought to satisfy two requirements simultaneously:
- Create a uniform coating that will fully isolate electrodes from the electrolyte, and
- Create an ultra-thin film that will allow the lithium ion and electron to easily tunnel without a large increase in impedance.
Conventional technologies have been unable to fulfill those requirements and have proved incapable of precisely controlling the coating film properties of film thickness and morphology.
As a result, battery performance can be unstable.
Argonne’s innovation, a powder nanocoating technology using metal oxides, has the following features:
- Gas-phase surface chemical reactions;
- A layer of extremely uniform metal oxide ultrathin film on granular cathode materials with precisely controlled surface morphology: smooth, conformal, and pin-hole free so that the electrode degradation reactions in the battery can be suppressed (figure 1); and
- Film so ultra-thin and precisely controlled in its thickness that the transfer of the charge across the electrode/electrolyte interface takes place with a very limited, or even a reduced, interface resistance.
The benefits of the Argonne technology include an ultra-thin-film powder coating processing technology and device, as well as advanced lithium-ion cathode materials.
The new powder coating technology provides:
- Smooth fluidization of ultrafine powders via non-linear processing control;
- Online, real-time monitoring of powder fluidization status and surface chemical reaction;
- Well-controlled properties of the nanocoated film (conformity, thickness, and composition); and
- A novel process that is scalable, less energy-intensive, and at a lower cost.
Lithium-ion batteries made of these novel coated materials offer:
- Isolation of electrode from electrolyte, creating greater structural stability and effectively enhancing capacity retention;
- Greater stability;
- Longer lifespan;
- Higher energy/power densities;
- Greater safety; and
- Reduced cost and increased performance (figure 2) reliability.
- Hybrid electric vehicles
- Solar cells
|Technology ID||Development Stage||Availability||Published||Last Updated|