EY9L54 18V 5.0 Ah battery
It is replaced by the EY9L54B 18V 5.0 Ah battery.
The EY9L54 is Lithium Ion battery pack for the 18 volt battery system from Panasonic.
The battery has a nominal voltage of 18 volts with a capacity of 5.0 Ah. Inside the battery pack are 10 18650 Lithium Ion cells with a capacity of 2.5 Ah each.
Availability
The EY9L54 seems to have been replaced with the EY9L54B which has a similar exterior and specifications. See that page for more information about this battery.