increase antenna gain with electric current?

Not only will it not help, but that also has an increased chance of blowing out your receiver!

Don't do it.

Your receiver works on "tiny" amounts of voltage, even 9v has a chance of burning out your receiver.

If you want more gain, add an antenna amp that is correctly designed, and might include high and low filters to get rid of interference.

Here's an example - but not endorsing it, just an example:

Increase the gain with a battery? 

Do you mean a battery powered signal amplifier? 

Or do you mean a VHF/UHF battery?

Rabbit ears would work better. Heat DECREASES current. Numpty.

Steel will decrease in conductivity when hot.

A TV reflector can be made using steel mesh (galvanised) of small spacings, or multiple parallel metal rods, their length being a little larger than a 1/4 wavelength of the lowest VHF frequency, with another set (in front of it, or 1/4 wavelength from the UHF radiating element) also 1/4 wavelength long of the lowest UHF frequency.

You are totally misunderstanding about getting gain, it cannot be done with a battery. You would need to get a well designed masthead amplifier, which gets its power from a plugpack- type supply at the TV set, and supplies it to the amplifier via the coaxial cable. This also has an isolation system to prevent the power reaching the set's antenna terminals/ socket.Most high- gain wideband fringe antennas are of the mixed VHF/ UHF log periodic design, although there are also 'flat plate' type antennas that have multiple elements.

That won't work unless you use the battery to power an RF amplifier. Better to power the amplifier from the mains.

Increase the TV signal gain by either adding more directors to the antenna, or install a TV RF amplifier at the antenna terminals. Battery alone would not give any gain to RF signal except generates heat.  Black paint coating absorb heat does not help at all in electrical conductivity, a foolish idea except protect the steel from rusting.

you should research some designs .. they tend to be directional and a box configuration, i think they call it a pepperbox, is used for maximum range ...

No. And if you wire your battery such that current flows into the receiver, you may burn out an input transformer that was not designed for dc.