Active material for battery, manufacturing method of the same, non-aqueous electrolytic battery and battery pack

Abstract

An active material for a battery includes a mixed phase includes a lithium titanium composite oxide phase and a nonstoichiometric titanium oxide phase. This active material is excellent in lithium absorption/desorption performance, exhibiting high electric potentials in lithium absorption/desorption and high conductivity.

1 . An active material for a battery, comprising a mixed phase comprising a lithium titanium composite oxide phase and a nonstoichiometric titanium oxide phase. 
   
   
       2 . The active material according to  claim 1 , wherein the lithium titanium composite oxide phase has a spinel type structure or a ramsdellite type structure. 
   
   
       3 . The active material according to  claim 1 , wherein the lithium titanium composite oxide phase is represented by a chemical formula of: Li 4+w Ti 5 O 12  (0≦w≦3) or Li 2+y Ti 3 O 7  (0≦y≦3). 
   
   
       4 . The active material according to  claim 1 , wherein the nonstoichiometric titanium oxide phase has a Magneli structure represented by a general formula of: Ti n O 2n−1  (4≦n≦10), a rhombic structure represented by a general formula of: TiO n  (1.85≦n≦2), a monoclinic structure represented by a general formula of: Ti 3 O 5 , or a hexagonal structure represented by TiO. 
   
   
       5 . The active material according to  claim 1 , wherein a main peak intensity of the nonstoichiometric titanium oxide phase is confined to not less than 1 and not more than 20 when the main peak intensity of the lithium titanium composite oxide phase is assumed as 100. 
   
   
       6 . The active material according to  claim 1 , wherein the lithium titanium composite oxide phase or the nonstoichiometric titanium oxide phase further comprises at least one element selected from the group consisting of Nb, Ta, P, Na and K. 
   
   
       7 . The active material according to  claim 1 , wherein the active material is powdery and has an average particle diameter of not less than 0.1 μm and not more than 1 μm in the primary particle. 
   
   
       8 . A method of manufacturing an active material for a battery, comprising:
 sintering a mixture containing raw lithium material and raw titanium material to produce a powder of mixed phase comprising a lithium titanium composite oxide phase and a titanium dioxide phase; and   sintering the powder of mixed phase in a reducing gas atmosphere at a temperature of not less than 600° C. and not more than 1000° C.   
   
   
       9 . The method according to  claim 8 , wherein the sintering of the mixture is performed at a temperature of not less than 680° C. and not more than 1000° C. 
   
   
       10 . A method of manufacturing an active material for a battery, comprising:
 sintering a mixture containing raw lithium material and raw titanium material to produce a powder of mixed phase comprising a lithium titanium composite oxide phase and a titanium dioxide phase; and   sintering the powder of mixed phase in the presence of carbon powder in an inert gas atmosphere at a temperature of not less than 600° C. and not more than 1000° C.   
   
   
       11 . The method according to  claim 10 , wherein the sintering of the mixture is performed at a temperature of not less than 680° C. and not more than 1000° C. 
   
   
       12 . A non-aqueous electrolyte battery comprising:
 an outer case;   a positive electrode housed in the outer case;   a negative electrode housed in the outer case in a manner that it is spaced away from the positive electrode, the negative electrode containing an active material including a mixed phase comprising a lithium titanium composite oxide phase and a nonstoichiometric titanium oxide phase; and   a non-aqueous electrolyte accommodated in the outer case.   
   
   
       13 . The battery according to  claim 12 , wherein the non-aqueous electrolyte includes a mixed solvent comprising two or more kinds of solvent selected from the group consisting of propylene carbonate, ethylene carbonate and γ-butyrolactone. 
   
   
       14 . The battery according to  claim 12 , wherein the non-aqueous electrolyte includes γ-butyrolactone as a solvent. 
   
   
       15 . The battery according to  claim 12 , wherein the positive electrode contains lithium cobalt composite oxide or lithium manganese composite oxide as an active material. 
   
   
       16 . A battery pack comprising a plurality of the non-aqueous electrolyte batteries each defined in  claim 12 , which are respectively electrically connected with each other in series, in parallel, or in series and parallel. 
   
   
       17 . The battery pack according to  claim 16 , which further comprises a protective circuit for detecting the voltage of the non-aqueous electrolyte batteries.