Electrochemical performance as cathode of lithium iron silicate, borate and phosphate glasses with different Fe2 + fractions

• Lithium iron silicate glasses with different Fe2 + fractions were prepared.
• The packing density increased with increasing Fe2 + fraction.
• Lithium ion battery performance as cathode was examined.
• The discharge capacity in the first cycle at 100/C was 54.6 mAh g− 1.
• It was demonstrated for the first time that glasses work as cathode.

Lithium iron silicate glasses with different fractions of Fe2 + ions of 40Li2O–10Fe2O3–50SiO2 (mol%) are prepared by conventional melt-quenching method and reducing heat treatment technique, and their electrochemical properties as cathode materials for Li+ ion secondary batteries (LIBs: lithium ion batteries) are examined. It is demonstrated for the first time that Li2O–Fe2O3–SiO2 glasses work as cathode in LIBs, e.g., the discharge capacity at 100/C in the first cycle is 54.6 mAh g− 1. The heat treatment at 350 °C in 5% H2/Ar induces not only the increase in the fraction of Fe2 + ions but also the increase in the packing density and the decrease in the electrical conductivity. It is clarified that the discharge capacity of the glasses is largely improved due to the increase in the fraction of Fe2 + ions. The data on thermal, physical, and discharge properties obtained in 40Li2O–10Fe2O3–50SiO2 glasses are compared with those in borate and phosphate glasses of 40Li2O–10Fe2O3–50(B2O3, P2O5).