-( Story related, cannot be missed )-
*While this is "flagged" as possibly story related, the real note is that... you could scrape by without having all 101 Power Cells early on. It would be in your best interest to avoid back-tracking at the end to get this for the final ending.
Level: Snowy Mountain
You will find three Lurker troops trying to break their way into some Dark Eco containers that have been frozen in the mountain surface while traversing the snow. Deal with the minor threats and then pick up some Red Eco to deal with the Brute that came prepared with a shield. One hit will neutralize the defenses, and then another hit will solve your problem of the troop.
The first one can be found after you clear the long jump and avoid the ice golem. Compete against the rolling snowballs to scale up the path and then turn left, where you will see the troops ramming at the containers.
The second will be found if you pass the snowballs, take the next path that leads downward. Instead of crossing the bridge, drop down and then take the nearby path leading further down. This will take you to an out-of-the-way nook where the troops are taking their time to get to the containers as well. Make sure you stepped into the Red Eco vent above before coming down, or else you won't be able to make a dent in the Brute's defenses.
The last Lurker troop will be found if you go back to where the icy bridge was mentioned for the second troop and cross it. Immediately follow the edge to the right until you get to some Precursor platforms rising and falling on an icy hill. Once you get to the top of the ice, you will see a Red Eco vent. Just to the left following the mountainside will be the last bit of Lurkers and the Brute needed for this Power Cell and trophy.