Negative electrode active material, nonaqueous electrolyte battery, battery pack and vehicle

Abstract

A negative electrode active material includes lithium-titanium composite oxide porous particles having an average pore size of 50 to 500 Å.

1 . A nonaqueous electrolyte battery, comprising:
 a positive electrode;   a negative electrode comprising lithium-titanium composite oxide porous particles having an average pore size of 50 to 500 Å and having a pH value of 10 to 11.2; and   a nonaqueous electrolyte.   
     
     
         2 . The nonaqueous electrolyte battery according to  claim 1 , wherein the average pore size of the lithium-titanium composite oxide porous particles is 100 to 500 Å. 
     
     
         3 . The nonaqueous electrolyte battery according to  claim 1 , wherein the lithium-titanium composite oxide porous particles have pores having a size not larger than 10 Å, and a specific volume of the pores is not smaller than 0.001 mL/g. 
     
     
         4 . The nonaqueous electrolyte battery according to  claim 3 , wherein the specific volume of the pores is 0.001 to 0.01 mL/g. 
     
     
         5 . The nonaqueous electrolyte battery according to  claim 1 , wherein the lithium-titanium composite oxide porous particles have a specific pore volume not smaller than 0.01 mL/g. 
     
     
         6 . The nonaqueous electrolyte battery according to  claim 5 , wherein the specific pore volume of the lithium-titanium composite oxide porous particles is 0.01 to 1 mL/g. 
     
     
         7 . The nonaqueous electrolyte battery according to  claim 1 , wherein the lithium-titanium composite oxide porous particles comprise a lithium titanate phase having a spinel structure. 
     
     
         8 . The nonaqueous electrolyte battery according to  claim 1 , wherein the lithium-titanium composite oxide porous particles have a pH value of 10.3 to 11. 
     
     
         9 . The nonaqueous electrolyte battery according to  claim 1 , wherein the lithium-titanium composite oxide porous particles have an average particle diameter not larger than 1 μm. 
     
     
         10 . The nonaqueous electrolyte battery according to  claim 1 , wherein the nonaqueous electrolyte comprises at least two solvents selected from the group consisting of propylene carbonate, ethylene carbonate and γ-butyrolactone. 
     
     
         11 . The nonaqueous electrolyte battery according to  claim 1 , wherein the nonaqueous electrolyte comprises LiBF 4 . 
     
     
         12 . The nonaqueous electrolyte battery according to  claim 1 , wherein the nonaqueous electrolyte has a viscosity not lower than 5 cp at 20° C. 
     
     
         13 . The nonaqueous electrolyte battery according to  claim 1 , wherein the positive electrode comprises a compound represented by Li a Ni b CO c Mn d O 2 , where 0≦a≦1.1, 0.1≦b≦0.5, 0≦c≦0.9 and 0.1≦d≦0.5. 
     
     
         14 . The nonaqueous electrolyte battery according to  claim 1 , wherein the negative electrode comprises a negative electrode current collector formed of an aluminum foil or an aluminum alloy foil. 
     
     
         15 . The nonaqueous electrolyte battery according to  claim 14 , wherein each of the aluminum foil and the aluminum alloy foil has an average crystal grain size not larger than 50 μm. 
     
     
         16 . A battery pack, comprising nonaqueous electrolyte batteries, each nonaqueous electrolyte battery comprising:
 a positive electrode;   a negative electrode comprising lithium-titanium composite oxide porous particles having an average pore size of 50 to 500 Å and having a pH value of 10 to 11.2; and   a nonaqueous electrolyte.   
     
     
         17 . The battery pack according to  claim 16 , wherein at least one of the nonaqueous electrolyte batteries comprise:
 a case having a first sealed section formed at one edge portion, and a second sealed section formed at another edge portion positioned on the opposite side of said one edge portion;   a positive electrode terminal including a tip portion withdrawn to an outside via the first sealed section of the case; and   a negative electrode terminal including a tip portion withdrawn to the outside via the second sealed section of the case.   
     
     
         18 . A vehicle comprising the battery pack defined in  claim 16 . 
     
     
         19 . A negative electrode active material comprising lithium-titanium composite oxide porous particles having an average pore size of 50 to 500 Å and having a pH value of 10 to 11.2. 
     
     
         20 . The negative electrode active material according to  claim 19 , wherein the lithium-titanium composite oxide porous particles have pores having a size not larger than 10 Å, and a specific volume of the pores is not smaller than 0.001 mL/g.