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US-12626912-B2 - Active material, all solid state battery, and methods for producing active material

US12626912B2US 12626912 B2US12626912 B2US 12626912B2US-12626912-B2

Abstract

A main object of the present disclosure is to provide an active material wherein the volume variation of an electrode layer during charge/discharge may be suppressed. The present disclosure achieves the object by providing an active material used for an all solid state battery, the active material comprising at least Si, and in infrared spectrum, when a maximum peak intensity in 900 cm −1 or more and 950 cm −1 or less is regarded as I 1 , and a maximum peak intensity in 1000 cm −1 or more and 1100 cm −1 or less is regarded as I 2 , the I 1 and the I 2 satisfy 0.55≤I 2 /I 1 ≤1.0, and 0.01≤I 1 .

Inventors

  • Mitsutoshi Otaki
  • Jun Yoshida
  • Tetsuya WASEDA
  • Masanori Harata
  • Tatsuya Eguchi

Assignees

  • TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date
20260512
Application Date
20211108
Priority Date
20201111

Claims (9)

  1. 1 . An active material for an all solid state battery, the active material comprising at least Si, and in an infrared spectrum, when a maximum peak intensity in 900 cm −1 or more and 950 cm −1 or less is regarded as I 1 , and a maximum peak intensity in 1000 cm −1 or more and 1100 cm −1 or less is regarded as I 2 , the I 1 and the I 2 satisfy 0.55≤I 2 /I 1 ≤1.0; wherein: the active material comprises at least one of a silicon clathrate II type crystal phase or a silicon clathrate I type crystal phase; the active material includes a void inside a primary particle; and a void amount of the void with a fine pore diameter of 100 nm or less is 0.05 cc/g or more and 0.15 cc/g or less.
  2. 2 . An all solid state battery comprising a cathode layer, an anode layer, and a solid electrolyte layer formed between the cathode layer and the anode layer, and the anode layer includes the active material according to claim 1 , and a solid electrolyte.
  3. 3 . The active material according to claim 1 , wherein a void ratio is 4% or more and 40% or less.
  4. 4 . The active material according to claim 1 , wherein the I 1 and the I 2 satisfy 0.727≤I 2 /I 1 ≤0.931.
  5. 5 . The active material according to claim 1 , wherein the void is observable with a scanning electron microscope.
  6. 6 . A method for producing an active material for an all solid state battery, the active material comprising at least Si, in an infrared spectrum, when a maximum peak intensity in 900 cm −1 or more and 950 cm −1 or less is regarded as I 1 , and a maximum peak intensity in 1000 cm −1 or more and 1100 cm −1 or less is regarded as I 2 , the I 1 and the I 2 satisfy 0.55≤I 2 /I 1 ≤1.0, the active material comprises at least one of a silicon clathrate II type crystal phase or a silicon clathrate I type crystal phase, the active material includes a void inside a primary particle, a void amount of the void with a fine pore diameter of 100 nm or less is 0.05 cc/g or more and 0.15 cc/g or less, the method comprising: a synthesizing step of synthesizing a first precursor, a washing step of obtaining a second precursor by washing the first precursor with an organic solvent or an acid having specific dielectric constant of 5 or more, and a drying step of obtaining the active material by drying the second precursor by heat.
  7. 7 . The method for producing an active material according to claim 6 , wherein the organic solvent is a ketone.
  8. 8 . The method for producing an active material according to claim 6 , wherein the synthesizing step includes: an alloying treatment of obtaining an alloy compound by alloying a Li based material and an intermediate including at least one of a silicon clathrate II type crystal phase, a silicon clathrate I type crystal phase, or a diamond type Si crystal phase, and a Li removing treatment of removing Li from the alloy compound and forming a void inside a primary particle.
  9. 9 . The method for producing an active material according to claim 8 , wherein, in the Li removing treatment, the Li is removed from the alloy compound using an ethanol.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2020-188134, filed on Nov. 11, 2020, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to an active material, an all solid state battery, and methods for producing an active material. BACKGROUND ART An all solid state battery is a battery including a solid electrolyte layer between a cathode layer and an anode layer, and has advantages in that it is easy to simplify a safety device as compared with a liquid battery including a liquid electrolyte containing flammable organic solvents. Also, as an active material to be used for the all solid state battery, a Si based active material has been known. For example, Patent Literature 1 discloses an anode for a sulfide all solid state battery comprising an anode active material layer including at least one kind of material selected from a group consisting of Si and a Si alloy, as an anode active material. Also, Patent Literature 2 discloses a silicon oxide structure including a silicon oxide skeleton including Si and O in the atomic composition; and silicon based nanoparticles chemically bonded to the silicon oxide skeleton, as constituents. Further, Patent Literature 2 discloses that, in the spectrum measured by an infrared spectroscopy, the ratio (I1/I2) of the intensity (I1) of peak 1 deriving from Si—H bond located in 820 cm−1 or more and 920 cm−1 or less and the intensity (I2) of peak 2 deriving from Si—O—Si bond located in 1000 cm−1 or more and 1200 cm−1 or less, is in a predetermined range. Also, in Patent Literature 3 discloses SiOx (anode active material for a lithium ion secondary battery) wherein, in the spectrum measured by an infrared spectroscopic instrument, the ratio value A1/A2 of the intensity of peak A1 deriving from a silanol group located in 3400 cm−1 or more and 3800 cm−1 or less and the intensity of peak A2 deriving from a siloxane bond located in 1000 cm−1 or more and 1200 cm−1 or less, is 0.1 or less. Also, Patent Literature 4 discloses an anode active material comprising a base particle composed of silicon oxide, and a coating layer that is composed of a conductive carbon material and coats at least a part of a surface of the base particle, wherein the intensity at 900 cm−1 is 0.30 or more, when the maximum peak intensity in 600 cm−1 to 1400 cm−1 in infrared absorption spectrum obtained by infrared spectroscopic measurement is regarded as 1. CITATION LIST Patent Literatures Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2018-142431Patent Literature 2: JP-A No. 2019-119638Patent Literature 3: JP-A No. 2011-108635Patent Literature 4: International Publication WO2014/119238 SUMMARY OF DISCLOSURE Technical Problem The theoretical capacity of Si is large, which is useful in high energy condensation of a battery. On the other hand, the volume variation of Si is large during charge/discharge. Therefore, the volume variation of an electrode layer using Si is large during charge/discharge. The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide an active material wherein the volume variation of an electrode layer during charge/discharge may be suppressed. Solution to Problem The present disclosure provides an active material used for an all solid state battery, the active material comprising at least Si, and in infrared spectrum, when a maximum peak intensity in 900 cm−1 or more and 950 cm−1 or less is regarded as I1, and a maximum peak intensity in 1000 cm−1 or more and 1100 cm−1 or less is regarded as I2, the I1 and the I2 satisfy 0.55≤I2/I1≤1.0, and 0.01≤I1. According to the present disclosure, since the value of I2/I1 is in a predetermined range, and further, since the value of I1 is also in a predetermined range, an active material wherein the volume variation of an electrode layer during charge/discharge may be suppressed, may be obtained. In the disclosure, the I1 may satisfy 0.02≤I1≤0.08. Also, the present disclosure provides an active material used for an all solid state battery, the active material comprising at least Si, and in infrared spectrum, when a maximum peak intensity in 900 cm−1 or more and 950 cm−1 or less is regarded as I1, and a maximum peak intensity in 1000 cm−1 or more and 1100 cm−1 or less is regarded as I2, the I1 and the I2 satisfy 0.55≤I2/I123 1.0, and 0.01≤I2. According to the present disclosure, since the value of I2/I1 is in a predetermined range, and further, since the value of I2 is also in a predetermined range, an active material wherein the volume variation of an electrode layer during charge/discharge may be suppressed, may be obtained. In the disclosure, the I2 may satisfy 0.02≤I2≤0.08. In the disclosure, the active material may include at least one of a silicon clathrate II type crystal phase, a silic