3M Innovative Properties Company scientists Jeffrey R Dahn, Jing Li and Mark N Obrovac reveal negative electrode nano-compositions for lithium-ion electrochemical cells that include metal oxides and polymeric binders in U.S. Patent Application 20090297948. Also provided in the patent application are electrochemical cells and battery packs that include electrodes made with these compositions. Crystalline, non-intercalating metal oxides transformed to a composite of nano-sized metal grains and nano-sized Li2O grains during lithium insertion are a key material for increasing the useful life of a lithium battery.
The use of the 3M negative electrode materials and electrodes, electrochemical cells, and battery packs made from them can provide reduced irreversible capacity and fade. The irreversible first cycle capacity loss in these electrodes can be significantly decreased by forming the electrode using 3M’s binders. The provided binders can be used to prepare electrodes and cells that exhibit decreased first cycle irreversible capacity loss compared to electrodes or cells made with conventional polymeric binders.
Polymers, such as polyvinylidene fluoride, have been used as binders for metal, metal alloy, metal oxide and graphite-based lithium-ion cell electrodes. However, the first cycle irreversible capacity loss in the resulting cells can be unacceptably large, e.g., as large as 300 mAh/g or more for an electrode based on a powdered metal oxide material. In addition the capacity loss may be unacceptably large, e.g. as large as 70% capacity loss or more in 50 cycles for an electrode based on a powdered metal oxide material. 3M’s materials reduce capacity loss due to battery cycling.
The negative electrode composition includes a powdered material and a polymeric binder, wherein the powdered material includes a non-intercalating metal oxide. The metal oxide is capable of undergoing lithiation and delithiation. The polymeric binder includes at least one of a polyacrylic acid, a lithium polyacrylate, or a polyimide. The electrode compositions include a non-intercalating metal oxide. A non-intercalating metal oxide is a metal oxide into which lithium can be reversibly inserted and extracted electrochemically at room temperature and during this process the structure of the material is substantially changed. That is, the atomic structure of the metal oxide-containing material before lithium insertion and during lithium insertion is different.
Crystalline, non-intercalating metal oxides can be transformed to a composite of nano-sized metal grains and nano-sized Li2O grains during lithium insertion. Examples of useful non-intercalating metal oxide materials include Fe2O3, CoO, Co3O4, NiO, CuO, MnO, and LiFeO2. The electrode composition can also include at least one of an oxide of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, niobium, or tungsten.
Crystalline, non-intercalating metal oxides can be transformed to a composite of nano-sized metal grains and nano-sized Li2O grains during lithium insertion. Examples of useful non-intercalating metal oxide materials include Fe2O3, CoO, Co3O4, NiO, CuO, MnO, and LiFeO2. The electrode composition can also include at least one of an oxide of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, niobium, or tungsten.
