Search

EP-4068420-B1 - POSITIVE ACTIVE MATERIAL FOR ALL SOLID SECONDARY BATTERY, AND ALL SOLID SECONDARY BATTERY INCLUDING THE SAME

EP4068420B1EP 4068420 B1EP4068420 B1EP 4068420B1EP-4068420-B1

Inventors

  • KIM, YOUNGSOO
  • CHOI, BYUNGJIN
  • HONG, Sukgi
  • KIM, JONGMIN
  • LEE, JEONGHO
  • HAN, SANGIL

Dates

Publication Date
20260506
Application Date
20220330

Claims (14)

  1. A positive active material for an all-solid secondary battery (1), the positive active material comprising: a secondary particle including a plurality of primary particles; and a buffer layer on a surface of the secondary particle; wherein: the secondary particle includes a nickel lithium transition metal oxide represented by Formula 1b, the buffer layer includes a copper compound represented by Formula 2a or Formula 2b, <Formula 1b> Li a Ni b Co c M 4 d O 2 in Formula 1b, M 4 is Al, Mn, Zr, Mg, or a combination thereof; and a, b, c, and d satisfy the following relations: 0.9≤a≤1.1, 0.7≤b<1, 0<c≤0.3, 0<d≤0.3, and b+c+d=1; <Formula 2a> Cu y Cl z in Formula 2a, y and z satisfy the following relations: 1≤y≤5, and 1≤z≤5, <Formula 2b> Li x Cu y Cl z in Formula 2b, x, y, and z satisfy the following relations: 0<x≤3, 1≤y≤5, 1≤z≤5.
  2. The positive active material for an all-solid secondary battery as claimed in one or more of the preceding claims, wherein the positive active material includes the copper compound in an amount of 0.0005 mol% to 0.2 mol%, in particular in an amount of 0.005 mol% to 0.1 mol%, based on 100 mol% of the nickel lithium transition metal oxide.
  3. The positive active material for an all-solid secondary battery as claimed in one or more of the preceding claims, wherein the copper compound is further included at interfaces between the plurality of primary particles.
  4. The positive active material for an all-solid secondary battery as claimed in one or more of the preceding claims, wherein the buffer layer is in a crystalline phase; or wherein the buffer layer is in a mixed phase of a crystalline phase and an amorphous phase.
  5. The positive active material for an all-solid secondary battery as claimed in one or more of the preceding claims, wherein the nickel lithium transition metal oxide includes nickel in an amount of 80 mol% to 98 mol%, based on a total number of moles of transition metals in the nickel lithium transition metal oxide.
  6. The positive active material for an all-solid secondary battery as claimed in one or more of the preceding claims, wherein the positive active material has a remainder of lithium of 100 ppm or more.
  7. A cathode for an all-solid secondary battery, the cathode including a positive active material layer (12), the positive active material layer (12) including the positive active material for an all-solid secondary battery as claimed in any one of claims 1 to 6.
  8. The cathode for an all-solid secondary battery as claimed in claim 7, the positive active material layer (12) further comprising a solid electrolyte.
  9. The cathode for an all-solid secondary battery as claimed in claim 8, wherein: the solid electrolyte is a sulfide solid electrolyte, and the sulfide solid electrolyte includes Li 2 S-P 2 S 5 , Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -LiBr, Li 2 S-P 2 S 5 -LiCl-LiBr, Li 2 S-P 2 S 5 -Li 2 O, Li 2 S-P 2 S 5 -Li 2 O-LiI, Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 S-B 2 S 3 , Li 2 S-P 2 S 5 -Z m S n , in which m and n are each independently a positive number, and Z is Ge, Zn, or Ga, Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li p MO q , in which p and q are each independently a positive number, and M is P, Si, Ge, B, Al, Ga, or In, Li 7-x PS 6-x Cl x , in which 0≤x≤2, Li 7-x PS 6-x Br x , in which 0≤x≤2, and Li 7-x PS 6-x I x , in which 0≤x≤2.
  10. The cathode for an all-solid secondary battery as claimed in claim 8 or 9, wherein the cathode includes the solid electrolyte in an amount of 5 parts by weight to 10 parts by weight, based on 100 parts by weight of the cathode.
  11. An all-solid secondary battery (1), comprising: a cathode layer (10); an anode layer (20); and a sulfide solid electrolyte layer (30) between the cathode layer (10) and the anode layer (20); wherein the cathode layer (10) includes the cathode as claimed in one or more of claim 7 through 10.
  12. The all-solid secondary battery as claimed in claim 11, wherein: the anode layer (10) includes a negative electrode current collector (11) and a negative active material layer (12) on the negative electrode current collector (11), the negative active material layer (12) includes a negative active material and a binder, the negative active material is in a particle form, and an average particle diameter of the negative active material is 4 µm or less, whereby the average particle diameter is a median diameter D50 measured using a laser particle size distribution device.
  13. The all-solid secondary battery as claimed in claim 12, wherein: the negative active material includes a carbon negative active material, a metal negative active material, or a metalloid negative active material, and the carbon negative active material includes amorphous carbon or crystalline carbon.
  14. A method of manufacturing the positive active material for an all-solid secondary battery (1) as claimed in claim 1, the method comprising: coating a nickel lithium transition metal oxide represented by the following Formula 1b with a coating solution including a catalyst and LiOH, the catalyst including Cu n X m , in which X is Cl and n and m satisfy the following relations: 1≤n≤5 and 1≤m≤5, and drying and heat-treating the coated nickel lithium transition metal oxide, <Formula 1b> Li a Ni b Co c M 4 d O 2 in Formula 1b, M 4 is Al, Mn, Zr, Mg, or a combination thereof; and a, b, c, and d satisfy the following relations: 0.9≤a≤1.1, 0.7≤b<1, 0<c≤0.3, 0<d≤0.3, and b+c+d=1.

Description

1. Field Embodiments relate to a positive active material for an all-solid secondary battery and an all-solid secondary battery including the same. 2. Description of the Related Art Some lithium secondary batteries could easily ignite when exposed to moisture in the air, since they use liquid electrolytes, and stability issues have always been raised. As more electric vehicles are coming into use, stability is becoming more of an issue. As a result, recently, all-solid-state secondary batteries using a solid electrolyte made of an inorganic material have been considered, in order to improve safety. Examples may be found in US 10 290 861 B2 or KR 101 523 081 B1. An all-solid-state battery does not use a combustible organic dispersion medium, and thus may significantly reduce the likelihood of a fire or an explosion even if a short circuit occurs. Therefore, such an all-solid-state battery may greatly increase safety as compared to a lithium-ion battery using a liquid electrolyte. SUMMARY The invention is defined by the appended claims. The description that follows is subjected to this limitation. Any disclosure lying outside the scope of said claims is only intended for illustrative as well as comparative purposes. The embodiments may be realized by providing a positive active material for an all-solid secondary battery, the positive active material including a secondary particle including a plurality of primary particles; and a buffer layer on a surface of the secondary particle; wherein the secondary particle includes a nickel lithium transition metal oxide represented by Formula 1, the buffer layer includes a copper compound represented by Formula 2,         <Formula 1>     LiaNibM1cO2-eAe in Formula 1, M1 is an element of Groups 4 to 14, A is F, S, Cl, Br, or a combination thereof; and a, b, c, and e satisfy the following relations: 0.9≤a≤1.3, 0.5≤b<1, 0<c<1, b+c=1, and 0≤e<1.         < Formula 2 >     LixCuyXz in Formula 2, X is a halogen, and x, y, and z satisfy the following relations: 0≤x≤3, 1≤y≤5, and 1≤z≤5. Not falling under the protection scope of the present invention: In Formula 2, X may be F, Cl, Br, I, or a combination thereof. The copper compound represented by Formula 2 is represented by Formula 2a or Formula 2b,         <Formula 2a>     CuyClz in Formula 2a, y and z satisfy the following relations: 1≤y≤5, and 1≤z≤5,         <Formula 2b>     LixCuyClz in Formula 2b, x, y, and z satisfy the following relations: 0<x≤3, 1≤y≤5, 1≤z≤5. The positive active material may include the copper compound in an amount of about 0.0005 mol% to about 0.2 mol%, based on 100 mol% of the nickel lithium transition metal oxide. The positive active material may include the copper compound in an amount of about 0.005 mol% to about 0.1 mol%, based on 100 mol% of the nickel lithium transition metal oxide. The copper compound may be further included at interfaces between the plurality of primary particles. The buffer layer may be in a crystalline phase. The buffer layer may be in a mixed phase of a crystalline phase and an amorphous phase. Not falling under the protection scope of the present invention: The nickel lithium transition metal oxide represented by Formula 1 may be represented by Formula 1a,         <Formula 1a>     LiaNibM2cM3dO2-eAe in Formula 1a, M2 may be Co, Mn, Al, or a combination thereof; M3 may be boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu) ), zirconium (Zr), aluminum (Al), phosphorus (P), zinc (Zn), silicon (Si), niobium (Nb), cobalt (Co), or a combination thereof; A may be F, S, Cl, Br, or a combination thereof; and a, b, c, d, and e may satisfy the following relations: 0.8<a≤1.2, 0.7≤b<1, 0<c<1, 0<d<1, b+c+d=1, and 0≤e<1. The nickel lithium transition metal oxide represented by Formula 1 is represented by Formula 1b,         <Formula 1b>     LiaNibCocM4dO2 in Formula 1b, M4 is Al, Mn, Zr, Mg, or a combination thereof; and a, b, c, and d satisfy the following relations: 0.9≤a≤1.1, 0.7≤b<1, 0<c≤0.3, 0<d≤0.3, and b+c+d=1. The nickel lithium transition metal oxide may include nickel in an amount of about 80 mol% to about 98 mol%, based on a total number of moles of transition metals in the nickel lithium transition metal oxide. The positive active material may have a remainder of lithium of about 100 ppm or more. The remainder of lithium content means the mass of the remainder of lithium with respect to one million of the total mass of the positive active material layer. The embodiments may be realized by providing a cathode for an all-solid secondary battery, the cathode including the positive active material for an all-solid secondary battery according to an embodiment. The cathode for an all-solid secondary battery may further include a solid electrolyte. The solid electrolyte may be a sulfide solid electrolyte, and the sulfide solid electrolyte may include Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-