ALIOVALENT ANION PROTECTIVE LAYERS FOR ACTIVE METAL ANODES

摘要

Active metal anodes can be protected from deleterious reaction and voltage delay in an active metal anode-solid cathode battery cell can be significantly reduced or completely alleviated by coating the active metal anode (e.g., Li) surface with a thin layer of a chemical protective layer incorporating aliovalent (multivalent) anions on the lithium metal surface. Such an aliovalent surface layer is conductive to Li-ions but can protect lithium metal from reacting with oxygen, nitrogen or moisture in ambient atmosphere thereby allowing the lithium material to be handled outside of a controlled atmosphere, such as a dry room. Particularly, preferred examples of such protective layers include mixtures or solid solutions of lithium phosphate, lithium metaphosphate, and/or lithium sulphate. These protective layers can be formed on the Li surface by treatment with diluted solutions of the following acids: H3PO4, HPO3 and H2SO4 or their acidic salts in a dry organic solvent compatible with Li by various techniques. Such chemical protection of the Li or other active metal electrode significantly enhances active metal electrode protection and reduces the voltage delay due to protected anode's improved stability toward the electrolyte.