What is the ambient temperature affects battery performance?

Low temperatures (e.g. -15℃) will obviously reduce SONY NP-FM50 camcorder battery discharge rate. At -20℃ electrolyte is at its freezing point, NP-FM50 charger speed will greatly slow down. At low temperature (under -15℃) charge will raise the internal gas pressure and probably unseal the safety vent. Ambient temperature of 5℃ to 30℃ is the best range to get effective camcorder battery charge. Generally with temperature rising charge efficiency will become higher. But when the temperature rises to 45℃ or higher, the materials performance in the SONY NP-FM50 camcorder battery will be degenerated and battery service life will be shorten greatly.