Panasonic FZ-E1 series Operating Instructions Manual page 12

If the battery smells or leaks electrolyte, keep the
battery away from fire.
Overheating, fire, or rupture may result.
Do not place the battery in microwave ovens or
pressurized containers.
Sudden application of heat may damage the battery's case,
resulting in electrolyte leakage, overheating, smoke,
rupture, or fire.
12