A battery module, comprising: - a plurality of electrochemical cells arranged in a stack disposed within a housing, wherein the housing comprises: - a first sidewall and a second sidewall opposite the first sidewall, wherein the first and second sidewalls extend along the same direction as the stack such that each electrochemical cell of the plurality of electrochemical cells is disposed between the first sidewall and the second sidewall, and wherein each of the first and second sidewalls comprises a first surface, a second surface, characterised by a plurality of cooling channels extending through the corresponding first and second sidewall of the housing from the first surface to the second surface, wherein the plurality of cooling channels is configured to permit fluid flow therethrough for cooling the plurality of electrochemical cells by heat transfer from the plurality of electrochemical cells, through at least a portion of the housing, and to the plurality of cooling channels, and wherein at least one cooling channel of the plurality of cooling channels comprises: - a first cross-sectional area across the first surface of the corresponding first or second sidewall and a second cross-sectional area across the second surface of the corresponding first or second sidewall, wherein the first cross-sectional area and the second-cross sectional area are different; and - a tapered portion extending between the first-cross sectional area and the second cross-sectional area. - a plurality of electrochemical cells arranged in a stack disposed within a housing, wherein the housing comprises: - a first sidewall and a second sidewall opposite the first sidewall, wherein the first and second sidewalls extend along the same direction as the stack such that each electrochemical cell of the plurality of electrochemical cells is disposed between the first sidewall and the second sidewall, and wherein each of the first and second sidewalls comprises a first surface, a second surface, characterised by a plurality of cooling channels extending through the corresponding first and second sidewall of the housing from the first surface to the second surface, wherein the plurality of cooling channels is configured to permit fluid flow therethrough for cooling the plurality of electrochemical cells by heat transfer from the plurality of electrochemical cells, through at least a portion of the housing, and to the plurality of cooling channels, and wherein at least one cooling channel of the plurality of cooling channels comprises: - a first cross-sectional area across the first surface of the corresponding first or second sidewall and a second cross-sectional area across the second surface of the corresponding first or second sidewall, wherein the first cross-sectional area and the second-cross sectional area are different; and - a tapered portion extending between the first-cross sectional area and the second cross-sectional area. - a first sidewall and a second sidewall opposite the first sidewall, wherein the first and second sidewalls extend along the same direction as the stack such that each electrochemical cell of the plurality of electrochemical cells is disposed between the first sidewall and the second sidewall, and wherein each of the first and second sidewalls comprises a first surface, a second surface, characterised by a plurality of cooling channels extending through the corresponding first and second sidewall of the housing from the first surface to the second surface, wherein the plurality of cooling channels is configured to permit fluid flow therethrough for cooling the plurality of electrochemical cells by heat transfer from the plurality of electrochemical cells, through at least a portion of the housing, and to the plurality of cooling channels, and wherein at least one cooling channel of the plurality of cooling channels comprises: - a first cross-sectional area across the first surface of the corresponding first or second sidewall and a second cross-sectional area across the second surface of the corresponding first or second sidewall, wherein the first cross-sectional area and the second-cross sectional area are different; and - a tapered portion extending between the first-cross sectional area and the second cross-sectional area.