We present a cooperative protocol to charge quantum spin networks up to the highest-energy configuration, in terms of the network's magnetization. The charging protocol leverages spin-spin interactions and the crossing of a phase transition's critical point to achieve superextensive charging precision. The cooperative protocol guarantees a precision advantage over any local charging protocol and leads to fluctuations (standard deviation) of the magnetization that scale as 1/N, with N the number of spins in the network, i.e., the size of the spin battery. We test our protocol on the D-Wave Advantage quantum processing unit by charging sublattices with sizes ranging from 40 to 5612 spins, achieving the highest-energy configuration with a sizable superextensive charging precision scaling and outperforming the local charging precision by four orders of magnitude.
