Highly reversible lithium metal secondary battery using a room temperature ionic liquid/lithium salt mixture and a surface-coated cathode active material.

For the purpose of realizing high-voltage, high-capacity, long-life and safe rechargeable batteries, a lithium secondary battery that uses high-voltage stable ZrO2-coated LiCoO2 cathode powder and a nonvolatile high-safety room temperature ionic liquid was fabricated.