A cell module and modular cell tray apparatus for a modular electrochemical device that are more easily manufactured and serviced. A cell module is provided having a plurality of electrochemical cells. The cell module includes an electrically conductive carrier element having a plurality of apertures, wherein each aperture is configured to accept a top portion of an electrode body of an electrochemical cell. A modular cell tray apparatus is provided having a plurality of the cell modules. The cell tray apparatus includes an electrically insulating tray having rows of cell receptacles to accept the cell modules. A modular electrochemical device is provided having a plurality of the cell tray apparatuses. The modular electrochemical device includes a plurality of electrical connectors configured to electrically connect the cell modules within a cell tray apparatus, and to electrically connect the cell tray apparatuses to each other.