Abstract: Systems and methods for the storage of energy that can be easily converted to electrical power are disclosed. A concentration battery includes a stack of alternating cation and anion exchange membranes separated from one another by alternating first and second spaces; a first reservoir containing a concentrated ionic solution; a second reservoir containing a dilute ionic solution; multiple spaced first fluid pathways in fluid communication with the first reservoir and configured to flow concentrated ionic solution flows into the first spaces; and multiple spaced second fluid pathways in fluid communication with the second reservoir and configured to flow dilute ionic solution flows into the second spaces. The fluid pathways may be configured to flow the ionic solutions in a common first direction. Electrodes at either end of the device in fluid communication with the concentrated ionic solution permit electrical energy to be applied or extracted. A related method is included.