Energy storage element and battery

A secondary energy storage element, comprising:

• a cathode and an anode as parts of an assembly;
• the cathode and anode being separated by a separator or solid electrolyte layer in a sequence cathode/separator or solid electrolyte layer/anode;
• and
• a first contact metal sheet and/or a second contact metal sheet,
• wherein the cathode comprises a cathode current collector and a positive electrode material,
• wherein the anode comprises an anode current collector and a negative electrode material,
• wherein:
• the cathode current collector comprises a main region loaded on both sides with a layer of the positive electrode material, and a free edge strip that extends along an edge of the cathode current collector and is not loaded with the positive electrode material, and/or
• the anode current collector comprises a main region loaded on both sides with a layer of the negative electrode material, and a free edge strip that extends along an edge of the anode current collector and is not loaded with the negative electrode material,
• wherein the cathode and the anode are formed and/or arranged relative to one another within the assembly such that the free edge strip of the cathode current collector protrudes from one side of the assembly and/or the free edge strip of the anode current collector protrudes from another side of the assembly, and
• wherein the first contact metal sheet is in direct contact with one of the free edge strips and/or the second contact metal sheet is in direct contact with the other of the free edge strips,
• wherein the electrodes comprise at least one ion type from the group comprising sodium ions, potassium ions, calcium ions, magnesium ions, and aluminum ions, which are exchanged between the cathode and the anode during charging and discharging of the secondary energy storage element.