the present invention relates to an accessory for high - voltage direct - current energy cables comprising : at least one element made from a crosslinked elastomeric polymer material , and at least one scavenging layer comprising zeolite particles . the zeolite particles are able to scavenge , very efficiently and irreversibly , the by - products deriving from the cross - linking reaction , so as to avoid space charge accumulation in the element during the accessory lifespan . moreover , the zeolite particles can prevent the crosslinking by - products present in the element of a non - degassed accessory from migrating towards the insulating layer of the energy cable on which the accessory is mounted .