Battery cell thermal runaway barrier

A thermal runaway barrier operatively adapted for being disposed between battery cells of a battery assembly and for at least significantly slowing down a thermal runaway event within the battery assembly, said thermal runaway barrier consisting essentially of:

• a single-layer of a nonwoven fibrous thermal insulation comprising a fiber matrix of inorganic fibers, thermally insulative inorganic particles dispersed within the fiber matrix, and a binder dispersed within the fiber matrix so as to hold together the fiber matrix;
• and
• an organic encapsulation layer encapsulating the single-layer of nonwoven fibrous thermal insulation.