Systems, structures and materials for electrochemical device thermal management

A container for the thermal management and protection of an electrochemical cell pack configured to be in physical contact with a plurality of electrochemical cells, wherein;

• the container being formed of a shape-stable composite solid-solid phase change material that is substantially solid at room temperature and that is machinable, wherein the container defines a plurality of through receptacles each shaped to receive an electrochemical cell with its positive and negative terminals exposed, the composite comprising:
• a first material having a polymer matrix comprising two or more temperature management materials dispersed therein,
• at least one of the two or more temperature management materials comprising;
• a polymeric phase change material comprising a cured polyether polyol having a crosslinking agent:polyether polyol ratio of 0.5:1 to 1.5:1, thereby having a latent heat of at least 5 Joules per gram and a transition temperature between 24° C. and 140° C., and
• at least one other of the two or more temperature management materials comprising;
• an elastomeric material;
• wherein the polymer matrix is substantially homogeneous,
• and wherein, in an environment where the electrochemical cell pack and a second electrochemical cell pack operate under the same charging and discharging conditions, the container reduces a first operating temperature of at least one electrochemical cell in the electrochemical cell pack by at least 10° C. compared to a second operating temperature of at least one electrochemical cell of the second electrochemical cell pack encased by a second container comprising the first material and not the polymer matrix.