Encapsulated alloy electrodes

A method of fabricating an active metal battery electrode, the method comprising:

• contacting a current collector metal layer with an active metal alloying metal layer;
• annealing the current collector metal layer and the active metal alloying metal layer such that a bond is formed there-between by alloying at the interface of the current collector metal layer and the active metal alloying metal layer to form a substantially at least two-dimensionally stable annealed layer;
• providing a substantially impervious barrier layer on the annealed layer, said barrier layer being conductive to ions of the active metal;
• and
• applying an active metal to said annealed layer prior to providing the barrier layer, such that the active metal alloys with the active metal alloying layer in the annealed layer to form a charged active metal alloy electrode;
• wherein the active metal alloying metal layer is tin and the active metal is lithium;
• and
• wherein the lithium is applied in stoichiometric excess to the tin in the annealed layer to form a lithiated annealed layer;
• and
• wherein the barrier layer is provided on the annealed layer by a process comprising,
• depositing a second layer of tin on the barrier layer to form a first structure,
• contacting the second layer of tin on the barrier layer of the first structure with the lithiated annealed layer comprising a second structure, such that a bond is formed between the two structures by alloying of tin and excess lithium in the respective structures.