TECHNOLOGY FOCUS - ELECTRONICS - Preferred Assembly: In the battery assembly, the sleeve is shaped such that the sealing portion of the sleeve is on opposing sides of the opening through the casing wall. The sleeve is shaped such that the sealing portion of the sleeve surrounds a periphery of the opening through the casing wall, where the sleeve comprises a battery cell cavity having a length and a width substantially identical to a length and width of the battery cell. The sleeve has a height that is less than a height of the battery cell. The casing wall comprises a top portion and a bottom portion and where the opening is through the top portion of the casing wall. The sleeve is sized such that when the sleeve is inserted into the opening, a gap is formed between a bottom of the sleeve and the bottom portion of the casing wall. The battery cell comprises an upper portion extending from the coolant chamber and first and second terminals connected to the upper portion. The sleeve is made of a rubber material. The battery cell is a prismatic battery cell. Alternatively, the battery assembly comprises: a casing comprising a casing wall having inner and outer surfaces and a set of openings through it and being shaped such that a coolant chamber is formed within the casing adjacent to the set of openings; a set of sleeves, each comprising a compressible material and being inserted through one of the set of openings, the sleeves being shaped such that a sealing portion is positioned over the outer surface of the casing wall; a set of battery cells, each battery cell being inserted into one of the set of sleeves such that at least a portion is positioned within the coolant chamber; and at least one sealing member coupled to the casing such that a force is applied onto the sealing portion of each of the set of sleeves causing the sealing portion of each of the sleeves to at least partially compress and seal the coolant chamber. The casing wall further comprises first and second coolant ports extending through it and in fluid communication with the coolant chamber. Each of the set of sleeves is inserted into a respective one of the set of openings through the casing wall, and each of the set of battery cells is inserted into a respective one of the sleeves. The set of openings through the casing wall and the sleeves are sized and shaped such that the sealing portion of each of the set of sleeves is adjacent to the sealing portion of another sleeve. The set of sleeves are interconnected. In the automotive battery assembly, each of the set of sleeves is shaped such that the sealing portion surrounds a periphery of the respective slot through the casing wall. Each of the set of sleeves comprises a battery cell cavity having a length and a width substantially identical to a length and a width of the respective battery cell. The casing wall further comprises a top portion and a bottom portion, each of the slots extending through the top portion of the casing wall, and each of the set of sleeves is sized such that a gap is formed between a bottom of the sleeve and the bottom portion of the casing wall when the sleeve is inserted into the respective slot. The set of battery cells are prismatic lithium ion battery cells.