What is claimed is:1. An active material comprising:a composite oxide having an orthorhombic crystal structure and represented by a general formula of Li2+wNa2?xM1yTi6?zM2zO14+δ, whereinthe M1 is at least one selected from the group consisting of Cs and K,the M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al, andw is within a range of 0≤w≤4, x is within a range of 0<x<2, y is within a range of 0≤y<2, z is within a range of 0<z≤6, and δ is within a range of ?0.5≤δ≤0.5.2. The active material according to claim 1, wherein the M2 is at least one selected from the group consisting of trivalent Fe, Co, Mn and Al, tetravalent Zr and Sn, pentavalent V, Nb and Ta, and hexavalent Mo and W.3. The active material according to claim 1, wherein, in an X-ray diffraction diagram for the composite oxide obtained by a powder X-ray diffraction method using Cu-Kα rays, an intensity ratio IL/IH is within a range of 2.25≤IL/IH≤3.5, wherein the intensity IL is an intensity of a strongest diffraction peak appearing in a range of 17°≤2θ≤18.5°, and the intensity IH is an intensity of a strongest diffraction peak appearing in a range of 18.5°≤2θ≤19.5°.4. The active material according to claim 1, wherein the orthorhombic crystal structure belongs to a space group Fmmm, andin an X-ray diffraction diagram for the composite oxide obtained by a powder X-ray diffraction method using Cu-Kα rays, an intensity ratio IL1/IH1 is within a range of 2.25≤IL1/IH1≤3.5, wherein the intensity IL1 is an intensity of a diffraction peak corresponding to a (111) plane, and the intensity IH1 is an intensity of a diffraction peak corresponding to a (202) plane.5. The active material according to claim 1, wherein,the composite oxide is represented by a general formula of Li2+wNa2?xM1yTi6-zM2zO14+δ,the M2 is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al, andw is within a range of 0≤w≤4, x is within a range of 0<x<2, z is within a range of 0<z≤6, y is 0, and δ is within a range of ?0.5≤δ≤0.5.6. The active material according to claim 1, wherein the M2 comprises Nb.7. The active material according to claim 1, wherein the M2 comprises two or more elements which have different valences and the M2 is selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn, and Al.8. The active material according to claim 1, wherein the composite oxide is a particle, the active material further comprises a layer covering at least a part of a surface of the particle of the composite oxide, and the layer comprises carbon and/or lithium titanate.9. The active material according to claim 1, wherein the active material is an active material for a battery.10. A nonaqueous electrolyte battery comprising:a negative electrode comprising the active material according to claim 1;a positive electrode; anda nonaqueous electrolyte.11. The nonaqueous electrolyte battery according to claim 10, whereinthe negative electrode comprises a current collector and a negative electrode layer formed on the current collector,the negative electrode layer comprises the active material,a density of the negative electrode layer is in a range of 1.8 g/cm3 to 2.8 g/cm3.12. A battery pack comprising the nonaqueous electrolyte battery according to claim 10.13. A battery pack comprising nonaqueous electrolyte batteries, each of which comprises:a negative electrode comprising the active material according to claim 1;a positive electrode; anda nonaqueous electrolyte,wherein the nonaqueous electrolyte batteries are electrically connected in series and/or in parallel.14. A battery module comprising nonaqueous electrolyte batteries, each of which comprises:a negative electrode comprising the active material according to claim 1;a positive electrode; anda nonaqueous electrolyte, andwherein the nonaqueous electrolyte batteries are electrically connected in series.
