All-solid battery and method of manufacturing the same

1. An all-solid battery that does not employ organic compound, comprising: two electrode layers composed of a positive electrode layer and a negative electrode layer interposing a solid electrolyte layer therebetween,

wherein at least one of the two electrode layers is composed of a sintered body of a mixed material including at least one or more types of electrode active material particles comprising electrode active material and solid electrolyte particles comprising solid electrolyte, and wherein a grain boundary of the electrode active material particles and the solid electrolyte particles including a portion of at least 30% by area of a grain boundary area surrounding the electrode active material particles has a coating layer with a thickness of 1 to 200 nm, and wherein

the coating layer is composed of a simple substance of C, or a metal consisting of any of the elements of Ni, Co, Fe, Mn, Cr, and Cu, or an alloy consisting of two or more of these elements.

2. The all-solid battery according to claim 1 , wherein content of the coating layer is 0.1% by mass or more in relation to an electrode active material, in at least one of the electrode layers.

3. The all-solid battery according to claim 1 , wherein content of a solid electrolyte particles is 10 to 70% by mass in relation to an electrode active material, in at least one of the electrode layers.

4. The all-solid battery according to claim 1 , wherein the solid electrolyte contained in the solid electrolyte particles is a chemical compound including a form of crystal having lithium ion conductivity.

5. The all-solid battery according to claim 4 , wherein the crystals having lithium ion conductivity have molecular formula Li 1+x+z M x (Ge 1−y Ti y ) 2−x Si z P 3−z O 12 , where 0≦x≦0.8, 0≦y≦1.0, 0≦z≦0.6, and M is at least one selected from Al or Ga.

6. The all-solid battery according to claim 1 , wherein the electrode active material is a material including at least one chemical element selected from the group consisting of C, Li, Mg, Mn, Fe, Co, Ni, B, Al, Ti, Si, Ge, Sn, Bi, W and O.

7. The all-solid battery according to claim 1 , wherein the solid electrolyte layer and the electrode layer composed of the sintered body are joined by calcining.

8. The all-solid battery according to claim 1 , wherein the grain boundary including a portion of at least 65% by area of the grain boundary area has a coating layer with a thickness of 1 to 200 nm.

9. An all-solid battery, comprising:

a positive electrode layer, a negative electrode layer and a solid electrolyte layer;

the solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer;

at least one of the positive and negative electrode layers is composed of a sintered body of a mixed material, wherein said mixed material comprises at least one of electrode active material particles and solid electrolyte particles, and a grain boundary of said electrode active material particles and said solid electrolyte particles has a coating layer;

said coating layer coats a portion of at least 30% by area of a grain boundary area surrounding said electrode active material particles and said coating layer has a thickness of 1 to 200 nm;

and wherein said coating layer is composed of a simple substance of C, or a metal consisting of any of the elements of Ni, Co, Fe, Mn, Cr and Cu, or an alloy consisting of two or more of these elements;

and wherein said all-solid battery does not employ organic compound.