U.S. patent application 20170358831 (applicant Pure Watercraft Inc., Seattle, Wash.):
"A battery pack assembly includes: a battery cell; a flat heat pipe, coupled to the battery cell, configured to transfer thermal energy to or from the battery cell; and a thermal electric cooler, coupled to the flat heat pipe, configured to cool the battery cell based on reducing the thermal energy through the flat heat pipe. ... The battery module can further include thermal storage units (e.g., PCM that melt and solidify at a phase change temperature; thermal energy can be absorbed or released based on the change in physical states of the materials) connected to the battery cells."
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