TECHNOLOGY FOCUS - POLYMERS - Preferred Module: In the Li-ion battery module, the base polymer comprises polypropylene, polyimide, polyamide, polyethylene (PET), polyphenylene sulfide (PPS), or rubber. The nanomaterial comprises silicate nanocomposites, nanocellulosic fibers, and individual or mixed nanometallic oxides. The polymer blend is injection molded to form the container. The Li-ion battery module comprises a heat sink overmolded by the polymer blend of the container such that the heat sink is retained in a portion of the container and is exposed along a bottom portion of the container; and a metalized surface disposed inside each compartment of the container, where the metalized surface is configured to increase thermal conductivity of the Li-ion battery module. The polymer blend comprises additives configured to increase a thermal conductivity of the container. The cover comprises the polymer blend. Alternatively, the Li-ion battery module comprises: a container comprising one or more partitions that define a set of compartments within the container, where each of the set of compartments is configured to receive and hold a prismatic Li-ion electrochemical cell element and electrolyte; and a cover configured to be disposed over the container to close the compartments; where the container comprises an electrically nonconductive polymeric material coated with a nanomaterial such that the nanomaterial forms a layer within each of the compartments, where the nanomaterial enhances the impermeability of the container to reduce ingress of moisture into the compartments and to reduce egress of the electrolyte from the compartments. The polymeric material coated with the nanomaterial is co-extruded to form the container. The container includes one or more layers of the polymeric material and one or more layers of the nanomaterial co-extruded to form the container, where the nanomaterial comprises a film spray-coated onto the polymeric material. The cover comprises the polymeric material coated with the nanomaterial. Preferred Cell: In the Li-ion battery cell, the nanomaterial is blended with the base polymer. The nanomaterial is coated onto the base polymer. The housing comprises a metalized surface configured to increase a thermal conductivity of the Li-ion battery cell. The Li-ion battery cell is a cylindrical Li-ion battery cell or a prismatic Li-ion battery cell. Preferred Method: Manufacturing the Li-ion battery module involves injection molding the base polymer to form the container; blending the nanomaterial into the base polymer to generate a polymer blend; and forming the container from the polymer blend. It also involves spraying the nanomaterial on to the base polymer after forming the container; and forming the container after applying the nanomaterial onto the base polymer.