Liquid Metal Batteries

There has been at least one exciting development in batteries
in recent years. A convenient name is liquid metal batteries.
They offer low manufacturing costs, extreme power density,
and suitability for grid-scale storage.

Sodium-sulfur batteries were known in the 1980's, as a well-
publicized research effort by Ford Motor Company. Those
devices differ from the new liquid metal batteries, particularly
in the form of the separator (electrolyte) between the
electroactive materials. They are closely related.

One of the key advantages of batteries with liquid electroactive
materials is that there are no morphology changes on cycling,
such that the cycle life of the active materials may approach
infinite. In the sodium-sulfur cells, this condition is met for
the anode and cathode materials (being molten sodium and
molten sulfur, respectively), but the solid electrolyte (a beta-
aluminum oxide ceramic ion conductor) is susceptible to
mechanical degradation by the phase change occurring as the
sodium ions are reduced to the metallic state, as well as by
the corrosive effects of liquid sodium.

In the new liquid metal batteries, molten salt serves as both
the separator and electrolyte. Density differences allow two of
the three liquid layers to float on the heaviest layer. In some
sense, the battery is self-assembling. The very high ionic
conductivity of the electrolyte allows for extreme power
density, well suited to grid-scale power storage. The safety
issues implicit in molten materials make them not particularly
attractive for use in electric vehicles, but in time may be
resolved. In the proof-of-concept cell by Donald Sadoway's
research group at MIT, the three layers, from bottom to top,
are antimony, sodium sulfide and magnesium. During
discharge, the top and bottom layers are consumed to form
magnesium antimonide, which dissolves in the electrolyte.
Upon recharge, the metal layers are reformed. If corrosion
issues for the electrodes and container can be resolved, the
cycle life may be nearly infinite.

I was pleased to receive from Mark Mack, a consultant to the
chemical industry, www.markmackllc.com, the article linked
below. It discusses state-of-the-art battery technology and
research and it reminded me about the important innovation in
battery technology represented by the liquid metal cells, so
directly led to this article. Dr. Mack, his coathor, Dr. Pitchai,
and Batteries International have kindly given permission to
distribute their article as part of the Techbriefing series.
The article can be found here:

http://sites.google.com/site/matbriefing/home/filecabinet/Batteries2010.pdf

Mark Mack is organizing a marvelous conference styled
Charged2020 http://www.charged2020.com/ to be held in San
Diego 30 June to 02 July 2010 to address energy storage
challenges. The importance of energy to the global economy
cannot be overstated.

Donald Sadoway of MIT discusses his invention of one liquid
metal battery:

http://www.buildbabybuild.com/news/prof-donald-sadoway-talks-about-liquid-battery-technology-review

An earlier article on innovations in battery technology can be
found here:

http://sites.google.com/site/matbriefing/home/filecabinet/SCAMPER2010.pdf

Another type of electrical energy storage device that employs
liquid electroactive materials has been called a flow battery,
a redox battery and redox regenerative fuel cell. Those devices
will be the subject of a future Techbriefing post.

Full disclosure: I have owned US Antimony (UAMY) stock for the past
5 years and this article made me think that it might be a good
idea to buy more. So I did. This is not investment advice. I
am not an investment adviser. Do not confuse this free article
with a recommendation to buy or sell any stock or other
financial vehicle.

miniature arc lamp with double the efficiency of LED lighting

This note describes a new light source that is a very small
microwave-excited xenon lamp. The plasma temperature is
in the range of 6000K, so it is very bright and very white. It
is quite remarkable that a bulb of approximately 5 mm diameter
and 10 mm length can put out as much light as a 400-watt
metal arc bulb. The color rendering is much better than the
various metal arc lamps. The manufacturer claims that the
efficiency is double that of solid state LED lighting devices.
There probably are some possibilities for using these devices
in several types of spectrometers. I am not endorsing the
company or the technology, but noting that it is very clever.

A nice photograph of it is here:
http://peswiki.com/index.php/Directory:Luxim_Corporation

A video of it in action:
http://www.youtube.com/watch?v=lTGsM9pplUs

How it works:
http://www.luxim.com/pdfs/TB1.pdf

The company website:
http://www.luxim.com/

The Company History
http://www.luxim.com/dynamic/display.php/32

LUXIM was founded in the year 2000 by technologists in the fields of plasma physics and high-frequency electronics to commercialize breakthrough developments in energy efficient, long-life lighting technology.

After engineering verification and receiving investment funding from Sequoia Capital and Worldview Technology Partners, LUXIM designed, manufactured and commercialized the first series of market leading LIFI solid state plasma lighting products.

They have been patenting diligently:

7,638,951 Plasma lamp with stable feedback amplification and method therefor
7,525,253 Microwave energized plasma lamp with dielectric waveguide
7,518,315 Microwave energized plasma lamp with solid dielectric waveguide
7,498,747 Plasma lamp with dielectric waveguide
7,429,818 Plasma lamp with bulb and lamp chamber
7,391,158 Plasma lamp with dielectric waveguide
7,372,209 Microwave energized plasma lamp with dielectric waveguide
7,362,056 Plasma lamp with dielectric waveguide
7,362,055 Plasma lamp with dielectric waveguide
7,362,054 Plasma lamp with dielectric waveguide
7,358,678 Plasma lamp with dielectric waveguide
7,348,732 Plasma lamp with dielectric waveguide
6,922,021 Microwave energized plasma lamp with solid dielectric waveguide
6,737,809 Plasma lamp with dielectric waveguide

Some recent newsclips describing the devices:

http://www.greentechmedia.com/articles/read/bridgelux-expands-led-bulb-options-while-luxim-does-a-plasma-street-light
http://www.treehugger.com/files/2008/04/luxim-plasma-lifi-light-bulb-led-cfl.php