Electrode materials for rechargeable battery
A positive electrode is disclosed for a non-aqueous electrolyte lithium rechargeable cell or battery. The electrode comprises a lithium containing material of the formula Na y Li x Ni z Mn 1-z-z′ M z′ O d , wherein M is a metal cation, x+y>1, 0<z<0.5, 0≦z′<0.5, y+x+1 is less than d, and the value of d depends on the proportions and average oxidation states of the metallic elements, Li, Na, Mn, Ni, and M, if present, such that the combined positive charge of the metallic elements is balanced by the number of oxygen anions, d. The inventive material preferably has a spinel or spinel-like component in its structure. The value of y preferably is less than about 0.2, and M comprises one or more metal cations selected preferably from one or more monovalent, divalent, trivalent or tetravalent cations, such as Mg 2+ , Co 2+ , Co 3+ , B 3+ , Ga 3+ , Fe 2+ , Fe 3+ , Al 3+ , and Ti 4+ . The electrode material can be synthesized using an ion-exchange reaction with a lithium salt in an organic-based solvent to partially replace sodium ions of a precursor material with lithium ions.
1. A lithium transition metal-oxide electrode suitable for use in a lithium cell, the electrode comprising a lithium containing material of the formula Na y Li x Ni z Mn 1-z-z′ M z′ O d , wherein M is a metal cation, x+y>1, 0<z<0.5, 0≦z′<0.5, y+x+1 is less than d, and the value of d depends on the proportions and average oxidation states of the metallic elements, Li, Na, Mn, Ni, and M, if present, such that the combined positive charge of the metallic elements is balanced by the number of oxygen anions, d; y is less than 0.2; and the lithium containing material includes a component with a spinel or spinel-like structure.
2. The electrode of claim 1 wherein M is present and is one or more metal cation selected from one or more monovalent, divalent, trivalent or tetravalent cations.
3. The electrode of claim 2 wherein M is at least one cation selected from the group consisting of Mg 2+ , Co 2+ , Co 3+ , B 3+ , Ga 3+ , Fe 2+ , Fe 3+3 , Al 3+ , and Ti 4+ .
4. The electrode of claim 1 wherein M is at least one cation selected from the group consisting of Mg 2+ , Co 2+ , Co 3+ , B 3+ , Ga 3+ , Fe 2+ , Fe 3+3 , Al 3+ , and Ti 4+ .
5. The electrode of claim 1 wherein 2<d≦3.
6. The electrode of claim 1 wherein the lithium containing material comprises a component selected from the group consisting of Na 0.02 Li 1.0 Ni 0.25 Mn 0.75 O d , Na 0.04 Li 1.24 Ni 0.25 Mn 0.75 O d , Na 0.09 Li 1.14 Ni 0.25 Mn 0.75 O d , and Na 0.02 Li 1.31 Ni 0.25 Mn 0.75 O d .
7. The electrode of claim 6 wherein the lithium containing material exhibits a high-intensity layered peak and small Li—Ni—Mn ordering peaks in the range of about 20-25° 2θ (CuKα).
8. The electrode of claim 1 wherein the lithium containing material has a morphology that comprises primary globule particles having a size in the range of about 5 nm to about 500 nm, and secondary particles having a size in the range of about 2 μm to about 20 μm.