The schematic symbol can be anything you want provided you include the correct number of pins that will be on the actual part and on the foot print used for the PCB layout.
Examples:
1.) If the battery plugs into the board then the symbol will be for a connector (header) with the correct number of pins.
2.) If the batteries are tubular with solid wires attached then a small battery shaped rectangle with a pin on each end would work. You could put the symbol for a battery in the rectangle.
3.) If you are using a 2 battery holder the symbol could look like the holder. (scaled down, not full size) If it has 4 pins then the symbol must have 4 pins.
When you make the footprint for the PCB layout it must match the number and location of the pins on the actual part and each pin must be on the symbol you made above. Also include lines on the silk screen (aka overlay) layer that is the outline of the actual part so you can see where it mounts to avoid putting other parts in its way. Remember to put the polarity (+/-) on the silk screen (aka overlay) layer.