Cathode additive for lithium secondary battery, preparation method therefor, cathode for lithium secondary battery, comprising same, and lithium secondary battery comprising same
The present disclosure relates to a positive electrode additive for a lithium secondary battery, a manufacturing method thereof. The positive electrode additive for a lithium secondary battery is represented by Chemical Formula 1 below. Li 6x Co 1-y M y O 4 [Chemical Formula 1] (In the Chemical Formula 1, 0.9≤x≤1.1, 0<y≤0.1, My=B a W b , 0≤a≤0.1, 0≤b≤0.1, and, a and b are not simultaneously 0.) Another positive electrode additive for a lithium secondary battery includes a core represented by Chemical Formula 2 below; and a coating layer comprising at least one of boron (B) and tungsten (W). Li 6x CoO 4 [Chemical Formula 2] (In the Chemical Formula 2, 0.9≤x≤1.1.)
1. A positive electrode additive for a lithium secondary battery represented by Chemical Formula 1 below:
Li 6x CO 1-y M y O 4 [Chemical Formula 1]
in the Chemical Formula 1, 0.9≤x≤1.1, 0<y≤0.1, M y =B a W b , 0<a≤0.1, 0<b≤0.1.
2. The positive electrode additive of claim 1 , wherein:
the positive electrode additive is coated with one or more of boron (B) and tungsten (W).
3. A positive electrode additive for lithium secondary battery, comprising:
a core represented by Chemical Formula 2 below; and
a coating layer comprising boron (B) and tungsten (W)
Li 6x CoO 4 [Chemical Formula 2]
in the Chemical Formula 2, 0.9≤x≤1.1.
4. A method of manufacturing a positive electrode additive for a lithium secondary battery represented by Chemical Formula 1 below, comprising:
preparing a precursor particle of CoO or Co(OH) 2 ;
preparing a mixture by mixing the precursor particle, lithium raw material, and doping raw material;
preparing a calcined product by calcining the mixture; and
cooling and pulverizing the calcined material;
wherein, the doping raw material comprises boron (B) and tungsten (W),
wherein, a mixing ratio of the precursor particle and the lithium raw material is 1:5.9 to 1:6.1 by molar ratio,
wherein, a mixing ratio of the doping raw material to the mixture is 0.001 to 0.02 by molar ratio,
wherein, in the step of preparing a calcined product by calcining the mixture,
Li 6x CO 1-y M y O 4 [Chemical Formula 1]
in the Chemical Formula 1, 0.9≤x≤1.1, 0<y≤0.1, M y =B a W b , 0<a≤0.1, 0<b≤0.1.
5. The method of claim 4 , wherein:
the lithium raw material is at least one selected from the group consisting of Li 2 CO 3 , LiOH, C 2 H 3 LiO 2 , LiNO 3 , Li 2 SO 4 , Li 2 SO 3 , Li 2 O, Li 2 O 2 , and LiCl.
6. The method of claim 4 , wherein:
in the step of preparing a calcined product by calcining the mixture,
the calcination condition is in an inert atmosphere for 1 to 15 hours at a temperature range of 600 to 800° C.
7. A method of manufacturing a positive electrode additive for lithium secondary battery represented by Chemical Formula 3 below, comprising:
preparing a compound represented by the following Chemical Formula 3;
preparing a mixture by mixing the compound and doping raw material;
preparing a calcined product by calcining the mixture; and
cooling and pulverizing the calcined material;
wherein, the doping raw material comprises boron (B) and tungsten (W),
wherein, a mixing ratio of the doping raw material to the compound represented by the Chemical Formula 3 is 0.001 to 0.02 by molar ratio:
Li 6x Co a B b W c O 4 [Chemical Formula 3]
in the Chemical Formula 3, 0.9≤x≤1.1, 0.9≤a≤1, 0≤b≤0.1, 0≤c≤0.1.
8. The method of claim 7 , wherein:
in the step of calcining the mixture to prepare a calcined product;
a calcining condition is in an inert atmosphere for 1 to 10 hours in a temperature range of 250 to 450° C.
9. The method of claim 4 or claim 7 , wherein:
after obtaining a lithium metal oxide, the method further comprises forming a coating layer by mixing the coating raw material with the lithium metal oxide and calcining that; and the coating raw material comprises at least one of boron (B) and tungsten (W).
10. A positive electrode for a lithium secondary battery, comprising:
a current collector; and
a positive active material layer positioned on the current collector surface;
wherein, the positive electrode active material layer comprises a positive electrode active material and a positive electrode additive,
the positive electrode additive is represented by the following chemical formula 3, and with respect to the sum of 100 wt % of the positive electrode active material and positive electrode additive, the positive electrode additive is 0.1 to 7 wt %”
Li 6x Co a B b W c O 4 [Chemical Formula 3]
In the Chemical Formula 3, 0.9≤x≤1.1, 0.9≤a≤1, 0<b≤0.1, and 0<c≤0.1.
11. The positive electrode of claim 10 , wherein:
the positive electrode additive is coated with at least one of boron (B) and tungsten (W).
12. The positive electrode of claim 10 , wherein:
the positive electrode additive is decomposed during initial charging and discharging and converted into a Li supply source and a compound represented by Chemical Formula 4 below
LiCo 1-y M y O 2 [Chemical Formula 4]
in the Chemical Formula 4, 0<y≤0.1, M y =B a W b , 0≤a≤0.1, and 0≤b≤0.1.
13. A lithium secondary battery, comprising:
a positive electrode;
a negative electrode; and
an electrolyte positioned between the positive and negative electrodes,
the positive electrode comprises the positive electrode additive according to claim 1 or claim 3 .