Electrode assemblies having alloyed interfaces and methods of forming the same

A method of preparing an electrode assembly for an electrochemical cell that cycles lithium ions, the method comprising:

• heating a precursor electrode assembly using a one-sided heating method, the precursor electrode comprising a current collector, a lithium metal foil, and an intermediate layer disposed between the current collector and the lithium metal foil, the intermediate layer comprising indium, gallium, or an alloy of indium and gallium, the heating comprising raising a temperature of the current collector to a temperature above a melting temperature of the intermediate layer such that a first surface of the intermediate layer adjacent to the current collector forms an alloy with a portion of the current collector opposing the intermediate layer and a second surface of the intermediate layer adjacent to the lithium metal foil forms an alloy with a portion of the lithium metal foil opposing the intermediate layer to form the electrode assembly, the portion of the current collector being at least 0.5% of an average thickness of the current collector, the portion of the lithium metal foil being at least 0.5% of an average thickness of the lithium metal foil, the intermediate layer together with the portion of the current collector and the portion of the lithium metal foil defining an alloyed interface that chemically binds the current collector and the lithium metal foil, the alloyed interface together with the current collector and the lithium metal foil defining the electrode assembly.