Porous Aluminium Could Boost Battery Life

Sumitomo Electric Industries has developed a porous aluminium substance that it says can increase the capacity of rechargeable batteries by up to three times.

The material, called Aluminium-Celmet (or Aluminum-Celmet), builds on Sumitomo’s previous work on a porous metal called Celmet, which is made from nickel or nickel-chrome alloy and has been adopted for use in the nickel-hydrogen batteries used in hybrid vehicles.

High porosity

Many battery improvements are focused on increasing the active surface area within the battery. Celmet does this with high porosity – up to 98 percent – which Sumitomo said is considerably higher than other porous metals such as nonwoven metal fabric and foam metal. The material has a three-dimensional mesh-like structure that forms interconnected, open and spherical pores. The structure of Celmet improves batteries’ filling, retaining and current-collecting performance, Sumitomo said.

Other approaches to increasing surface area in battery components have included the use of tobacco mosaic virus, and nanotubes.

The Celmet material is produced by applying an electro-conductive coating to plastic foam, which is then nickel-plated, following which a heat treatment is used to remove the plastic foam.

Aluminium-Celmet is produced via a similar process and has the same high porosity of Celmet, but is also about one-third the weight of nickel, offers greater electrical conductivity and is corrosion-resistant.

That makes it suitable for use in lithium-ion and other rechargeable batteries, the company said. It can also be used in current collectors in capacitors.

Replacing the aluminium foil in a conventional lithium-ion battery with Aluminium-Celmet increases the amount of positive active material per unit area and thus increases battery capacity, Sumitomo said.

It estimated that in the case of the batteries used in electric vehicles batteries based on the new material would have 1.5 to 3 times greater capacity.

Storage batteries

Alternatively, the volume of batteries with the same capacity could be reduced by one-third to two-thirds, which could be useful for instance in batteries used to store solar power in the home.

Sumitomo said it has set up a small-scale production line for Aluminium-Celmet and is working towards mass production of the material.

A number of battery manufacturers are working to dramatically extend capacity for the batteries used with laptops, with Lenovo, Sony, Dell and HP recently claiming battery life of between 10 and 32 hours in a clutch of laptop releases.

One enabler of the long battery life is the introduction of Intel’s Sandy Bridge family of processors with integral graphics capabilities, or 2nd Generation Core processors as they are now known, but better power management and innovative battery arrays also play their part.

Greater capacity

Lenovo’s T420 includes a nine-cell battery that offers 15 hours of battery life, and can be docked with a second battery to offer 30 hours of battery life.

Last year researchers from the University of Maryland discovered a way to vastly improve the capacity of lithium-ion batteries using the Tobacco mosaic virus (TMV). A biological virus, TMV is widely known for its destructive effects on tobacco, tomatoes, peppers and other plants. Its rigid rod-like shape, and its ability to bind to metal, enabled researchers to use it to increase the surface area of electrodes in a battery.

The resulting batteries have an up to ten-fold increase in energy capacity over standard lithium-ion batteries.

Researchers have also recently proposed using the energy from typing to help increase battery life.