I included a zipped including .svg icons to have battery gauge like mine, if you have a laptop is a good idea to have it matching sphere theme.
open terminal and type : sudo nautilus,go to /usr/share/cairo-dock/gauges/Battery and replace icons there, maybe is necessary to restart system.

A bordeless cairo-dock theme i have made using sphere icons.
More about my desktop theme:

http://forum.ubuntued.info/viewtopic.php?f=30&t=18&start=4580#p40979

ícons theme :

http://potzblitz7.deviantart.com/art/Sphere-1-2-5-373679678