Abstract: Quantum battery is a kind of quantum devices of storage energy, which has wide potential applications in many quantum small systems, such as quantum sensors, molecular motors and so on. Based on the framework of collision model, the effects of coherence of non-equilibrium environment on the storage energy of quantum battery have been studied when the battery is being charged in a nonequilibrium coherent environment. By deriving the quantum master equation describing the dynamics of system, the analytical expression for storage energy of quantum battery at steady state is given, and then the effects of squeezing coherence and heat-exchange coherence on the storage energy of quantum battery are discussed. It demonstrates that the squeezing coherence of auxiliary unit has no contribution to the storage energy of battery, but the heat-exchange coherence (including coherence magnitude and relative phase) can improve the storage energy of battery efficiently, and can be regarded as a kind of useful "fuel" resource for battery.

Key words: quantum battery, non-equilibrium coherent environment, quantum coherence, stored energy