Lithium ion secondary battery and a method for manufacturing the same

Abstract

A lithium ion secondary battery includes a positive electrode, a negative electrode and a thin film solid electrolyte including lithium ion conductive inorganic substance. The thin film solid electrolyte has thickness of 20 μm or below and is formed directly on an electrode material or materials for the positive electrode and/or the negative electrode. The thin film solid electrolyte has lithium ion conductivity of 10 −5 Scm −1 or over and contains lithium ion conductive inorganic substance powder in an amount of 40 weight % or over in a polymer medium. The average particle diameter of the inorganic substance powder is 0.5 μm or below. According to a method for manufacturing the lithium ion secondary battery, the thin film solid electrolyte is formed by coating the lithium ion conductive inorganic substance directly on the electrode material or materials for the positive electrode and/or the negative electrode.

What is claimed is:  
     
         1 . A lithium ion secondary battery comprising a positive electrode, a negative electrode and a solid electrolyte, said solid electrolyte being made in the form of a thin film comprising a lithium ion conductive inorganic substance.  
     
     
         2 . A lithium ion secondary battery as defined in  claim 1  wherein said thin film solid electrolyte has thickness of 20 μm or below.  
     
     
         3  A lithium ion secondary battery as defined in  claim 1  wherein said thin film solid electrolyte is formed directly on an electrode material or materials for the positive electrode and/or the negative electrode.  
     
     
         4 . A lithium ion secondary battery as defined in  claim 1  wherein said thin film solid electrolyte has lithium ion conductivity of 10 −5  Scm −1  or over.  
     
     
         5 . A lithium ion secondary battery as defined in  claim 1  wherein said thin film solid electrolyte comprises the inorganic substance in an amount of 40 weight % or over.  
     
     
         6 . A lithium ion secondary battery as defined in  claim 1  wherein said inorganic substance is a lithium ion conductive crystal.  
     
     
         7 . A lithium ion secondary battery as defined in  claim 1  wherein said inorganic substance is a lithium ion conductive glass.  
     
     
         8 . A lithium ion secondary battery as defined in  claim 1  wherein said inorganic substance is a lithium ion conductive glass-ceramic.  
     
     
         9 . A lithium ion secondary battery as defined in  claim 1  wherein said inorganic substance is powder of the inorganic substance.  
     
     
         10 . A lithium ion secondary battery as defined in  claim 9  wherein said inorganic substance powder is powder of a lithium ion conductive glass-ceramic.  
     
     
         11 . A lithium ion secondary battery as defined in  claim 9  wherein an average particle diameter of the inorganic substance powder is 1.0 μm or below.  
     
     
         12 . A lithium ion secondary battery as defined in  claim 9  wherein said thin film solid electrolyte comprises a lithium ion conductive inorganic substance powder in a polymer medium.  
     
     
         13 . A lithium ion secondary battery as defined in  claim 9  wherein said thin film solid electrolyte comprises a lithium inorganic salt and lithium ion conductive glass-ceramic powder in a polymer medium.  
     
     
         14 . A lithium ion secondary battery as defined in  claim 3  wherein said thin film solid electrolyte is formed by direct coating on an electrode material or materials for the positive electrode and/or the negative electrode.  
     
     
         15 . A lithium ion secondary battery as defined in  claim 3  wherein said thin film solid electrolyte is formed by crystallizing an amorphous layer which is formed by direct coating on an electrode material or materials for the positive electrode and/or the negative electrode.  
     
     
         16 . A lithium ion secondary battery as defined in  claim 1  comprising a positive electrode, a negative electrode and a solid electrolyte wherein said positive and/or negative electrode comprises lithium ion conductive inorganic substance powder.  
     
     
         17 . A lithium ion secondary battery as defined in  claim 16  wherein said inorganic substance powder in the positive and/or negative electrode has an average particle diameter of 3 μm or below.  
     
     
         18 . A method for manufacturing a lithium ion secondary battery having a thin film solid electrolyte comprising a lithium ion conductive inorganic substance comprising a step of forming the thin film solid electrolyte by coating the lithium ion conductive inorganic substance directly on an electrode material or materials for the positive and/or negative electrode.  
     
     
         19 . A method for manufacturing a lithium ion secondary battery as defined in  claim 18  comprising a step of preparing slurry comprising the lithium ion conductive inorganic substance, and a step of forming the thin film solid electrolyte by coating the slurry directly on the electrode material or materials for the positive and/or negative electrode.  
     
     
         20 . A method for manufacturing a lithium ion secondary battery as defined in  claim 18  comprising a step of coating the lithium ion conductive inorganic substance directly on the electrode material or materials for the positive and/or negative electrode to form an amorphous layer, and a step of forming the thin film solid electrolyte by crystallizing the amorphous layer.