Anulax Batteries are among the most powerful sources of energy in the universe. They are also very valuable, each battery being worth thousands of Units. Since they are so valuable, they are often the targets of thieves.
Sometime after the Battle of Xandar, Nebula attempted to steal some of the batteries but was ultimately arrested by the Sovereign. The Sovereign contacted the Guardians of the Galaxy and offered to hand over Nebula in exchange for the Guardians protecting the batteries from an Abilisk, a creature that eats energy sources.
During the battle with the Abilisk, Rocket is able to steal some of the batteries. The Sovereign later find out about the theft, and they send their Golden Drones to retrieve them. Once the drones failed to retrieve the batteries, Ayesha traveled to Contraxia and hired Yondu to retrieve them, offering to pay one million Units.
Once Yondu and the Ravagers find Rocket and the crashed Milano on Berhert, Rocket offers to give the batteries to Yondu in exchange for sparing the lives of Groot and himself. Yondu agrees and decides that he could sell the batteries and make more money than Ayesha was paying. This caused anger across the Ravagers, saying that Yondu had gone soft, with Taserface taking over the Ravagers.
During the Battle on Ego's Planet, Rocket used the Anulax Batteries to jury-rig an explosive in order to kill Ego the Living Planet. Groot took the bomb and placed it inside Ego's core, detonating it and destroying Ego and the Batteries.