Battery system and production method

A battery system comprising:

• a substrate defining a set of cells, each cell in the set of cells comprising:
• a base encompassed by a wall;
• and
• a set of fins extending from the base;
• an electrolyte material coating surfaces of the set of fins in each cell in the set of cells;
• a passivated material located across horizontal surfaces on the base and the set of fins in each cell in the set of cells;
• a cathode material arranged in each cell, in the set of cells, over the electrolyte material and the passivated material;
• and
• a cathode current collector electrically coupled to the cathode material and cooperating with the substrate to enclose each cell, in the set of cells, to form a multi-cell assembly;
• and
• wherein the multi-cell assembly is dividable along walls between adjacent cells, in the set of cells, to form a set of discrete batteries.