Apparatus comprising battery cells and a method of assembling

An apparatus comprising:

• a plurality of battery cells, each of the battery cells comprising a layer of positive electrode material, a layer of electrolyte material and a layer of negative electrode material;
• and
• a container for the battery cells, the container formed of an electrically conductive material and having a plurality of cavities, each cavity containing at least one of the battery cells,
• wherein the container is in direct contact with at least one of the layer of positive electrode material and the layer of electrolyte material of each battery cell, or alternatively the container is in direct contact with at least one of the layer of negative electrode material and the layer of electrolyte material of each battery cell,
• wherein each cavity has a first end closed by a combination of an insulating element and an electrical connector, the insulating element providing electrical insulation between the electrical connector and the container, and
• wherein the insulating element comprises a single insulating element that extends over one or more of the cavities.