High energy density molten lithium-selenium batteries with solid electrolyte

An electrochemical cell, comprising:

• an anode comprising lithium metal or a lithium alloy;
• a cathode comprising selenium;
• and
• a solid electrolyte positioned between the anode and the cathode, wherein the solid electrolyte is capable of conducting lithium ions, and
• a cathode current collector electrically connected with the cathode,
• wherein at operating temperatures, the lithium metal or the lithium alloy is molten, the selenium is molten, and the solid electrolyte remains solid,
• wherein the solid electrolyte comprises a garnet-type oxide, and the garnet-type oxide comprises Li7−xLa3Zr2−xTaxO12 wherein x is from 0.1 to 1.0, and
• wherein the solid electrolyte is in a form of a tube and the anode is disposed within the tube, and the cathode current collector is in the form of a cylinder outside the tube, and the cathode is disposed between the tube and the cylinder.