Electric wire and cable manufacturer Sumitomo Electric Industries has started a small-scale production line for its newly developed porous Aluminum-Celmet material, in Osaka, Japan, to accelerate development efforts towards mass production of the material.
The manufacturer reports it has succeeded in developing the porous Aluminum-Celmet material, using processes similar to those used for producing its trademark Celmet, a porous metal made from nickel or nickel alloy.
Celmet’s high porosity of up to 98% is considerably higher than that of other porous metals. The product also features a three-dimensional meshlike structure that forms interconnected, open and spherical pores.
Sumitomo states this enables favourable filling, retaining and current-collecting performance when used with an active material, which has led to Celmet being adopted as a positive electrode current collector in hybrid vehicle nickel-hydrogen batteries.
The trademark Aluminum-Celmet material offers the same high porosity as Celmet, but is lighter, as the specific gravity of aluminium is about one-third that of nickel.
Further, it also offers greater electrical conductivity, as its electrical resistivity is less than half that of nickel, and corrosion resistance.
This makes it suitable for use in lithium-ion and other secondary batteries operating at high charge or discharge voltages, for which Celmet made from nickel is not suitable.
Aluminum-Celmet can also be used for current collectors in capacitors.
The positive electrode current collector in a conventional lithium-ion secondary battery is made from aluminium foil, while the negative current collector is made from copper foil.
“Replacing the aluminium foil with Aluminum-Celmet increases the amount of positive active material per unit area,” states Sumitomo.
The manufacturer adds that trials under- taken by it have found that, in the case of automotive on-board battery packs, such replacement increases battery capacity by between 1.5 and 3 times.
“Alternatively, with no change in capacity, battery volume can be reduced to between one-third and two-thirds. “These changes afford such benefits as reduced footprint of home-use storage bat- teries for power generated by solar and other natural sources, as well as by fuel cells,” it notes.
Sumitomo aims to improve Aluminum-Celmet for commercialisation and mass production for lithium-ion battery and capacitor current collector application.