I would favour TWO layers of metallic protection, this need not be expensive or elaborate.
I use metal tins that previously contained biscuits, and these tins placed inside a metal filing cabinet.

Items that I store include

Two way radios.
Radio receivers.
Geiger counters.
LED light bulbs, various types including flashlight bulbs and vehicle bulbs.
LEDs, bare components not LED lamps.
Silicon rectifier diodes.
Electrical test meters.

Cellphones and PCs are in my view a lower priority as cellphone service is unlikely to be available, nor is an internet connection or enough power to work a PC likely to be available.

Zinc carbon batteries should survive just fine as should alkaline types and lead acid batteries.
Any more modern type of battery that incorporates electronics will probably be killed by an EMP.

It is worth storing the materials to make basic batteries, the raw materials keep forever and are invulnerable to an EMP.