TECHNICAL FIELD

The present disclosure discloses a cathode mixture used in a sulfur battery and a method for producing the cathode mixture.

BACKGROUND ART

In accordance with the rapid spread of information-related apparatuses and communication devices such as a personal computer, a video camera, and a portable telephone in recent years, the development of a battery used for the power source thereof is regarded as important. Also in the automobile industry, the development of a battery with high out-put and high capacity for electric vehicles or hybrid vehicles is in progress.

The development of a sulfur battery using sulfur as a cathode active material is in progress. The sulfur has a feature that the theoretical capacity thereof is extremely high as 1675 mAh/g. Also, in the field of a sulfur battery, an attempt has been made to improve the availability of the sulfur and to increase the charge and discharge capacities of a sulfur battery. Patent Literature 1 discloses a cathode mixture comprising a Li2S—P2S5based solid electrolyte, a cathode active material that is elemental sulfur, and a conductive material that is a carbon material. Patent Literature 1 describes a cathode mixture produced by mixing the following (a) to (c) with a planetary type ball mill, and an all solid state lithium-sulfur battery using the same: (a) as a solid electrolyte, a Li2S—P2S5based sulfide solid electrolyte preliminarily produced by a planetary type ball mill treatment, or a sulfide solid electrolyte preliminarily produced with a planetary type ball mill by using Li2S, red phosphorous, and sulfur as starting materials, (b) sulfur as a cathode active material, and (c) Ketjen black as a conductive auxiliary material.

Also, Patent Literature 2 describes a method for producing a cathode mixture, the method comprising steps of: a preparing step (1) of preparing a sulfide solid electrolyte configured an ion conductor including Li, P, and S, and LiBr; and an amorphizing step (2) of amorphizing a mixture including a sulfide solid electrolyte, a cathode active material that is elemental sulfur, and a conductive auxiliary material that is a carbon material, to obtain a cathode mixture.

Also, patent Literature 3 describes a method for producing a cathode mixture by mechanical milling, using sulfur, acetylene black, and 80Li2S-20P2S5sulfide solid electrolyte preliminarily produced by a planetary type ball mill as starting materials.

Further, Patent Literature 4 describes a cathode mixture produced by using a planetary type ball mill to Li2S and Li salt (LiI, LiBr, LiBnO3, LiBF4), and an all solid state battery using the cathode mixture.

Further, Patent Literature 5 describes a method for producing a cathode mixture by step (1) of mixing (A) sulfur or a corona product thereof, (B) a sulfur interfacial reaction improver preliminarily produced with a planetary type ball mill using Li2S and P2S5as starting materials (composition ratio (molar ratio) of Li2S:P2S5=65:35), and (C) a conductive material; and step (2) of mixing a 80Li2S-20P2S sulfide solid electrolyte preliminarily produced by a planetary type ball mill, and the mixture obtained in step (1).

CITATION LIST

Patent Literatures

Patent Literature 1: Japanese Patent (JP-B) No. 5445809Patent Literature 2: Japanese Patent Application Laid-Open (JP-A) No. 2017-091810Patent Literature 3: JP-A No. 2011-181260Patent Literature 4: International Publication No. WO2016/063877Patent Literature 5: JP-A No. 2014-160572

SUMMARY OF DISCLOSURE

Technical Problem

Since the availability of the sulfur is not sufficiently improved in conventional art, there is a need to further increase the charge and discharge capacities of a sulfur battery. The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a cathode mixture and a method for producing the same capable of improving the availability of the sulfur and increasing the charge and discharge capacities of the sulfur battery.

Solution to Problem

In order to achieve the object, the present disclosure provides a cathode mixture and a method for producing the same used in a sulfur battery, wherein the cathode mixture is produced by a mechanical milling treatment of a raw material mixture comprising: Li2S, LiX, in which X is selected from F, Cl, Br, or I, and MxSy, in which M is selected from P, Si, Ge, B, Al, or Sn, x and y is an integer that gives electric neutrality to S according to the kind of M; a cathode active material including an elemental sulfur; and a conductive auxiliary material including a carbon material.

By the mechanical milling of a raw material mixture comprising: Li2S, LiX, in which X is selected from F, Cl, Br, or I, and MxSy, in which M is selected from P, Si, Ge, B, Al, or Sn, x and y is an integer that gives electric neutrality to S according to the kind of M; a cathode active material including an elemental sulfur; and a conductive auxiliary material including a carbon material, a cathode mixture in which excellent interfaces between the sulfur and the solid electrolyte and between the sulfur and the conductive auxiliary material are formed, may be produced.

Advantageous Effects of Disclosure

The present disclosure exhibits effects such that a cathode mixture capable of improving the availability of sulfur and increasing the charge and discharge capacities of a sulfur battery may be produced.

