Positive electrode active material, electrochemical apparatus, and electronic device
View Patent ↗A positive electrode active material includes a conductive base material and an active substance distributed at the conductive base material. The active substance has a core-shell structure including a core layer material and a shell layer material. The conductive base material includes a carbon material, the core layer material includes a phosphate-based sodium salt material, and the shell layer material includes a metal oxide.
1. A positive electrode active material, comprising:
a conductive base material, and an active substance distributed at the conductive base material, the active substance having a core-shell structure, and the core-shell structure including a core layer material and a shell layer material;
wherein:
the conductive base material comprises a carbon material, the core layer material comprises a phosphate-based sodium salt material, and the shell layer material comprises a metal oxide;
a mass percentage of the shell layer material in the positive electrode active material is 1% to 10%;
a mass percentage of the conductive base material in the positive electrode active material is 1% to 10%; and
a median particle size of the positive electrode active material is 5 μm to 20 μm.
2. The positive electrode active material according to claim 1 , wherein the metal oxide comprises at least one of WO 3 , Al 2 O 3 , ZnO, CuO, or TiO 2 .
3. The positive electrode active material according to claim 1 , wherein the positive electrode active material has at least one of following features:
a chemical formula of the phosphate-based sodium salt material is Na x1 R y1 (PO 4 ) Z1 , where 1≤x 1 ≤3, 1≤y 1 ≤2, and 1≤z 1 ≤3, and R comprises least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Hf, Ta, W, or Pb;
the chemical formula of the phosphate-based sodium salt material is Na x2 R y2 (P 2 O 7 ) Z2 , where 1≤x 2 ≤7, 1≤y 2 ≤3, and 1≤z 2 ≤4, and R comprises at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Hf, Ta, W, or Pb;
the chemical formula of the phosphate-based sodium salt material is Na x3 R y3 (PO 4 ) Z3 (P 2 O 7 ) k3 , where 1≤x 3 ≤7, 1≤y 3 ≤4, 1≤z 3 ≤2, and 1≤k 3 ≤4, and R comprises at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Hf, Ta, W, or Pb; and
the chemical formula of the phosphate-based sodium salt material is Na x4 R y4 (PO 4 ) Z4 M l1 , where 1≤x 4 ≤3, 1≤y 4 ≤2, 1≤z 4 ≤2, and l≤l1≤3, R comprises at least one of Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sn, Hf, Ta, W, or Pb, and M comprises at least one of F, Cl, or Br.
4. The positive electrode active material according to claim 1 , wherein the phosphate-based sodium salt material comprises at least one of NaFePO 4 , Na 3 V 2 (PO 4 ) 3 , Na 2 FeP 2 O 7 , Na 2 MnP 2 O 7 , NaCoP 2 O 7 , Na 7 V 3 (P 2 O 7 ) 4 , Na 2 FePO 4 F, Na 3 V 2 (PO 4 ) 2 F 3 , Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ), Na 4 Mn 3 (PO 4 ) 2 (P 2 O 7 ), Na 4 Co 3 (PO 4 ) 2 (P 2 O 7 ), Na 4 Ni 3 (PO 4 ) 2 (P 2 O 7 ), or Na 7 V 4 (PO 4 )(P 2 O 7 ) 4 .
5. The positive electrode active material according to claim 1 , wherein an actual mass of oxygen atoms in the metal oxide is 70% to 95% of a theoretical mass of oxygen atoms in the metal oxide.
6. The positive electrode active material according to claim 1 , wherein the positive electrode active material has at least one of following features:
a thickness of the shell layer material is 50 nm to 400 nm; and
a mass percentage of the core layer material in the positive electrode active material is 90% to 99%.
7. The positive electrode active material according to claim 1 , wherein the positive electrode active material has at least one of following features:
the carbon material comprises at least one of carbon nanotubes, graphene, carbon fiber, natural graphite, or artificial graphite;
the carbon material comprises an oxygen-containing group comprising at least one selected from a carboxyl group, a hydroxyl group and an ether group;
the carbon material comprises an oxygen-containing group, and a mass percentage of oxygen atoms in the carbon material is greater than or equal to 0.1%; and
the conductive base material is a carbon material.
8. The positive electrode active material according to claim 1 , wherein the positive electrode active material has at least one of following features:
a resistivity of the positive electrode active material under a pressure of 20 MPa is 0.005 Ω·cm to 100 Ω·cm; and
a gram capacity of the positive electrode active material is 100 mAh/g to 180 mAh/g.
9. An electrochemical apparatus, comprising:
a positive electrode sheet, comprising a positive electrode active material comprising:
a conductive base material, and
an active substance distributed at the conductive base material, the active substance having a core-shell structure, and the core-shell structure including a core layer material and a shell layer material;
wherein:
the conductive base material comprises a carbon material, the core layer material comprises a phosphate-based sodium salt material, and the shell layer material comprises a metal oxide;
a mass percentage of the shell layer material in the positive electrode active material is 1% to 10%;
a mass percentage of the conductive base material in the positive electrode active material is 1% to 10%; and
a median particle size of the positive electrode active material is 5 μm to 20 μm;
a negative electrode sheet;
a separator; and
an electrolyte solution.
10. An electronic device, comprising:
an electrochemical apparatus, comprising:
a positive electrode sheet, comprising a positive electrode active material comprising:
a conductive base material, and
an active substance distributed at the conductive base material, the active substance having a core-shell structure, and the core-shell structure including a core layer material and a shell layer material;
wherein:
the conductive base material comprises a carbon material, the core layer material comprises a phosphate-based sodium salt material, and the shell layer material comprises a metal oxide;
a mass percentage of the shell layer material in the positive electrode active material is 1% to 10%;
a mass percentage of the conductive base material in the positive electrode active material is 1% to 10%; and
a median particle size of the positive electrode active material is 5 μm to 20 μm;
a negative electrode sheet;
a separator; and
an electrolyte solution.