Benjamin Chaloner-Gill

A vanadium-based cathode for lithium-ion batteries

A vanadium-based oxide system has been developed as a cathode for use in a lithium-ion battery. The lithiated material was made in two steps, i.e., I, making a Li-V-O and, 2, introducing lithium into the intercalation host by reducing the V(V) with S 2- ions in the form of lithium sulfide. The stoichiometry of the final product corresponds approximately to Li 4 V 3 O 7.9 . This material has shown excellent resistance to dissolution in 1 M LiPF 6 ethylene carbonate/dimethyl carbonate electrolyte. The capacity of the material cycling at a C/3 rate over the voltage range of 3.8-2.0 V is ∼220 mAh/g. Li 4 V 3 O 7.9 has demonstrated some stability in an ambient environment. This new cathode is capable of storing large amounts of energy, 630 mWh/g. Li 4 V 3 O 7 9 has exhibited long cycle life, greater than 100 deep discharge cycles vs. lithium metal.

Synthesis and properties of a vanadium oxide based lithium ion Cathode

The development of high capacity cathode materials for lithium ion batteries has resulted in three materials dominating the market, lithiated manganese, cobalt and nickel oxides and mixtures thereof. In the search for greater energy storage, the authors have examined a number of vanadium oxides. Comparing the ratio of lithium to metal atom in the three compounds listed above allows for the extraction of one lithium atom per two metal atoms. If the cathode is vanadium based, the number of cyclable lithiums increases to a value closer to 0.75--1.00. Despite the fact that vanadium oxides operate at lower voltages, a net gain in energy is observed from the use of Li{sub x}V{sub y}O{sub z} over the currently available materials. Lithiation of LiV{sub 3}O{sub 7.9} for use in a lithium ion cell is the focus of this paper. Chemical lithiation by reducing lithium salt will be described.