3500/4000 mah battery?

Do you think we can ask LG to create a battery of 3500/4000 mah for our devices? I am now using a cover of spigen which increases the thickness of the phone approximately 2/3 mm on the back.. if this could be used to create a battery with 3500/4000 mah capacity would not be bad .. the Mugen has created a battery of 3100 mah pretty much useless (original costs less and has only 100 mah less) and one of 6200 mah that makes the phone horrible!!

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