Abstract
To develop organic electrolytes for 4 V lithium metal rechargeable batteries, 
electrolytes with five‐, six‐, and seven‐ membered cyclic ether solvents were characterized. Among these examined electrolytes, 
/tetrahydropyran (THP) electrolyte was found to possess the most advantages, such as high cycling efficiency, good oxidation stability, and high boiling point. Furthermore, lithium cycling efficiency and conductivity were improved by mixing 50% ethylene carbonate (EC) in 
electrolyte. By using 
solute as an alternative to 
electrolyte, corrosion of the aluminum current collector was inhibited and therefore, excellent cycling performance of a 
coin cell was realized. It was also found that lithium cycling efficiency increased with decreasing deposition current density or increasing dissolution current density. Especially at deposition/dissolution current densities of 
, the observed lithium cycling efficiency in 
electrolyte was above 99%. Thermal tests further disclosed that this mixed electrolyte has good thermal stability even in the presence of lithium metal or cathode materials. © 1999 The Electrochemical Society. All rights reserved.