A battery encapsulation method includes disposing an active battery layer on each of a plurality of battery substrates, with each battery substrate having a greater area than its corresponding active battery layer. The plurality of battery substrates are attached to an interposer having a greater area than an aggregate area of the plurality of battery substrates. The active battery layers are environmentally sealed by disposing a film over the active battery layers sized such that the film extends beyond the active battery layers to contact the battery substrates and the interposer. The interposer is physically along locations where the film contacts the interposer so as to form a plurality of battery units, with each battery unit including one of the battery substrates with the associated active battery layer disposed thereon and being environmentally sealed by the film.