Non-aqueous electrolyte secondary battery and production method thereof

Abstract

A method for producing a non-aqueous electrolyte secondary battery comprising the steps of: (i) mixing a positive electrode active material, a first binder A and a dispersion medium to prepare a paste A, the active material comprising a lithium-containing transition metal oxide; (ii) mixing a conductive agent, a second binder B and a dispersion medium to prepare a paste B, the conductive agent comprising carbon black; (iii) mixing the paste A and the paste B to prepare a positive electrode material paste C; (iv) applying the positive electrode material paste C onto a positive electrode core member and rolling and drying the resultant member to prepare a positive electrode; and (v) fabricating a battery using the positive electrode, a negative electrode and a non-aqueous electrolyte, wherein contact angle θ A between the non-aqueous electrolyte and the binder A and contact angle θ B between the non-aqueous electrolyte and the binder B satisfy the formula (1): θ B −θ A ≧15°.

1 - 9 . (canceled) 
     
     
         10 . The non-aqueous electrolyte secondary battery in accordance with  claim 17 , wherein said agglomerated particles have a bulk density of not less than 0.1 g/ml and not more than 0.5 g/ml. 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The non-aqueous electrolyte secondary battery in accordance with  claim 17 , wherein said binder A is at least one selected from the group consisting of polyvinylidene fluoride, modified polyvinylidene fluoride and polytetrafluoroethylene. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . The non-aqueous electrolyte secondary battery in accordance with  claim 17 , wherein said paste further comprises a particulate binder comprising a cross-linked polymer such that the total amount of said binder A, said binder B and said particulate binder becomes not less than 0.5 part by weight and not more than 2 parts by weight per 100 parts by weight of said positive electrode active material. 
     
     
         17 . A non-aqueous electrolyte secondary battery comprising:
 a positive electrode comprising a positive electrode material layer and a positive electrode core member for supporting said positive electrode material layer, said positive electrode material layer comprising a positive electrode active material, a conductive agent, a first binder A and a second binder B, said positive electrode active material comprising a lithium-containing transition metal oxide, said conductive agent comprising carbon black;   a negative electrode comprising a negative electrode material layer and a negative electrode core member for supporting said negative electrode material layer; and   a non-aqueous electrolyte comprising a non-aqueous solvent dissolving a lithium salt,   wherein said conductive agent contained in said positive electrode material layer forms agglomerated particles having a particle size of less than 10 μm,   a contact angle θ A  between said non-aqueous electrolyte and said binder A and a contact angle θ B  between said non-aqueous electrolyte and said binder B satisfy the formula (1): θ B −θ A ≧15°, and said contact angle θ A  satisfies 10°≦θ A ≦30°, said contact angle θ B  satisfies 40°≦θ B ≦60°,   the amount of said conductive agent contained in said positive electrode material is not less than 1 part by weight and not more than 3 parts by weight per 100 parts by weight of said positive electrode active material, the total amount of said binder A and said binder B contained in said positive electrode material is not less than 0.5 part by weight and not more than 2 parts by weight per 100 parts by weight of said positive electrode active material, and   binder A and binder B are soluble in a dispersion medium of the positive electrode active material.   
     
     
         18 . The non-aqueous electrolyte secondary battery in accordance with  claim 17 , wherein binder B is mixed with the conductive agent to form a mixture of binder B and the conductive agent and binder A is subsequently mixed with the mixture of binder B and the conductive agent in a separate step.