There are Thunder Barriers of different strengths that can be identified with the symbol on the barrier. Increase the level of the Electrogranum at the Sacred Sakura's Favor to go through higher strength barriers. Mechanisms can also deactivate Thunder Barriers, either temporarily or permanently, without needing to increase Electrogranum level.
Thunder Barriers can also contain Thunderstones that deal Electro DMG over time to the player if they are not carrying an Electrogranum.
The more complex the Thunder Barrier symbol, the more powerful Electrogranum you need.