A battery module includes a plurality of battery cells connected in series, each battery cell having a cathode, an anode, and a separator separating the cathode and the anode, and a bipolar current collector; a plurality of polymer frames, each having a window to receive part of the one of the plurality of battery cells; two of the plurality of polymer frames defining a compartment; and electrolyte filling the compartment for one of the plurality of battery cells. A method is also provided.