Abstract: A thermal management matrix for an electrochemical cell array including a plurality of electrochemical cell elements, the thermal management matrix at least in part enveloping the electrochemical cell array and being in thermal contact therewith. The thermal management matrix includes mainly expanded graphite, wherein the expanded graphite is arranged in the form of a block-like structure and the block includes at least one layer of expanded graphite having a higher in-plane thermal conductivity than the layers neighboring the layer with higher in-plane thermal conductivity. The thermal management matrix may also include phase change materials as a latent heat storage material.