Lithium-ion secondary battery, battery apparatus, electrical apparatus, preparation method for positive electrode active material, and preparation method for positive electrode plate
The present disclosure relates to a lithium-ion secondary battery, a battery apparatus, an electrical apparatus, and preparation methods for a positive electrode active material and a positive electrode plate. The battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. The positive electrode plate comprises a current collector and a film layer disposed on at least one side of the collector. The film layer comprises a positive electrode active material including lithium-containing transition metal phosphate particles, at least part of the surfaces of which are coated with a carbon material. In a cross-section along the electrode plate thickness direction, the DA90 of the particles ranges from 1400 nm to 2100 nm, and the particle size concentration ratio (DA90−DA10)/DA50 ranges from 1.855 to 2.375, wherein DA90, DA50, and DA10 respectively denote the particle sizes corresponding to 90%, 50%, and 10% of the area cumulative distribution.
1 . A lithium-ion secondary battery, comprising a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector;
the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises lithium-containing transition metal phosphate particles, at least some surfaces of which are provided with a carbon coated material; and
in a cross section of the positive electrode film layer in an electrode plate thickness direction, D A90 of the particles ranges from 1400 nm to 2100 nm, and a particle size concentration ratio (D A90 −D A10 )/D A50 ranges from 1.855 to 2.375, wherein D A90 , D A50 , and D A10 refer to corresponding particle sizes of particles when area cumulative distributions of the particles reach 90%, 50%, and 10% in an area cumulative distribution curve of the particles.
2 . The lithium-ion secondary battery according to claim 1 , wherein
D A90 of the particles in the cross section of the positive electrode film layer in the electrode plate thickness direction ranges from 1400 nm to 2000 nm.
3 . The lithium-ion secondary battery according to claim 1 , wherein
D A50 of the particles in the cross section of the positive electrode film layer in the electrode plate thickness direction ranges from 600 nm to 900 nm.
4 . The lithium-ion secondary battery according to claim 1 , wherein
D A10 of the particles in the cross section of the positive electrode film layer in the electrode plate thickness direction ranges from 100 nm to 300 nm.
5 . The lithium-ion secondary battery according to claim 1 , wherein in a graphitization degree C value cumulative distribution curve of the positive electrode film layer that is obtained in a laser micro-confocal Raman spectrometer surface scanning mode, a graphitization degree median C50 ranges from 0.98 to 1.20; and a graphitization degree C value is IG/ID, wherein IG represents an intensity of a G peak at 1580±100 cm −1 of a Raman spectrum, and I D represents an intensity of a D peak at 1350±100 cm −1 of the Raman spectrum.
6 . The lithium-ion secondary battery according to claim 1 , wherein in the sphericity area cumulative distribution curve of the particles that are obtained from the cross section of the positive electrode film layer in the electrode plate thickness direction, the sphericity median L A50 ranges from 0.70 to 0.85.
7 . The lithium-ion secondary battery according to claim 1 , wherein
in a roughness area cumulative distribution curve of the particles that are obtained from the cross section of the positive electrode film layer in the electrode plate thickness direction, a roughness median R A50 ranges from 0.92 to 0.96; and/or
in the roughness area cumulative distribution curve of the particles that are obtained from the cross section of the positive electrode film layer in the electrode plate thickness direction, a roughness concentration ratio (R A90 −R A10 )/R A50 ranges from 0.05 to 0.10.
8 . The lithium-ion secondary battery according to claim 1 , wherein
an iron dissolution rate of the positive electrode film layer ranges from 400 ppm to 1800 ppm;
a mass content of a carbon element based on a total mass of the positive electrode active material ranges from 0.8% to 1.8%; and/or
a lithium-iron antisite defect concentration of the positive electrode active material ranges from 0.001% to 1.5%.
9 . The lithium-ion secondary battery according to claim 1 , wherein the lithium-containing transition metal phosphate comprises a component having the following general formula:
Li m Fe x P y O j Q q
wherein Q comprises one or more of Al, Na, K, Mg, Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb, V, Ti, B, S, Si, N, F, Cl, and Br, 0.8≤m≤1.15, 0.9≤x≤1, 0.95≤y≤1, 3.5≤j≤4, and 0<q≤0.1.
10 . The lithium-ion secondary battery according to claim 1 , wherein the positive electrode active material comprises one or more of lithium iron phosphate, a doped and modified material thereof, and a coated and modified material thereof.
11 . The lithium-ion secondary battery according to claim 1 , wherein
the positive electrode active material comprises a titanium element, and a mass content of the titanium element based on the total mass of the positive electrode active material ranges from 4000 ppm to 8000 ppm;
a powder tapped density of the positive electrode active material ranges from 1.00 g/cm 3 to 1.70 g/cm 3 ; and/or
a powder resistivity of the positive electrode active material under a pressure of 8 MPa ranges from 0.5 Ω·cm to 60.0 Ω·cm.
12 . The lithium-ion secondary battery according to claim 1 , wherein a discharge gram capacity of the positive electrode active material at a discharge rate of 1 C ranges from 135 mAh/g to 150 mAh/g.
13 . The lithium-ion secondary battery according to claim 1 , wherein a ratio of a discharge capacity of the positive electrode active material discharged to 3.2 V is η≥85%, wherein η is defined as follows: a button battery comprising the positive electrode active material is charged and discharged twice at a constant current with a rate of 0.1 C in a voltage range of 2.0 V to 3.75 V at a room temperature, and then is charged and discharged once at a constant current with a rate of 1 C; and in a charge and discharge test at the rate of 1 C, a capacity value at which a discharge voltage is 3.2 V is extracted and recorded as C 1 , a capacity value at which a discharge voltage is 2.0 V is extracted and recorded as C 2 , and η=C 1 /C 2 , wherein a charge process comprises constant-voltage charge with a constant voltage of 3.75 V and a constant-voltage cut-off current of 50 μA.
14 . The lithium-ion secondary battery according to claim 1 , wherein
a mass content of a conductive agent based on a total mass of the positive electrode film layer ranges from 0.01% to 1.5%; and/or
the positive electrode film layer further comprises a binder, and based on the total mass of the positive electrode film layer, a mass content of the positive electrode active material ranges from 94.0% to 99.4%.
15 . The lithium-ion secondary battery according to claim 1 , wherein
a single-sided surface density of the positive electrode film layer ranges from 300 mg/1540 mm 2 to 450 mg/1540 mm 2 ;
in a fully discharged state of the lithium-ion secondary battery, a compacted density of the positive electrode film layer ranges from 2.52 g/cm 3 to 2.78 g/cm 3 .
16 . The lithium-ion secondary battery according to claim 1 , wherein the positive electrode film layer satisfies at least one of the following:
(1) in a fully discharged state of the lithium-ion secondary battery, the compacted density of the positive electrode film layer ranges from 2.52 g/cm 3 to 2.78 g/cm 3 , and in the cross section of the positive electrode film layer in the electrode plate thickness direction, a porosity of the positive electrode film layer ranges from 10% to 22%; and
(2) in a fully discharged state of the lithium-ion secondary battery, the compacted density of the positive electrode film layer ranges from 2.55 g/cm 3 to 2.75 g/cm 3 , and in the cross section of the positive electrode film layer in the electrode plate thickness direction, a porosity of the positive electrode film layer ranges from 10% to 20%.
17 . The lithium-ion secondary battery according to claim 1 , wherein the positive electrode plate comprises an undercoating, and the undercoating is arranged between the positive electrode film layer and the current collector; and the undercoating satisfies at least one of the following:
(1) the undercoating comprises carbon-based particles, and a distribution density of the carbon-based particles having particle sizes greater than 100 nm in the undercoating is ≤10 pcs/10 μm;
(2) a compacted density of the positive electrode plate in the fully discharged state is greater than or equal to 2.4 g/cm 3 , and a single-sided thickness of the undercoating ranges from 1 m to 4 μm; and
(3) a compacted density of the positive electrode plate in the fully discharged state is greater than or equal to 2.5 g/cm 3 , and a single-sided thickness of the undercoating ranges from 2 μm to 4 μm.
18 . A battery apparatus, comprising the lithium-ion secondary battery according to claim 1 , wherein the battery apparatus comprises at least one of a battery module, a battery pack, and an energy storage battery.
19 . A preparation method for a positive electrode plate, wherein the preparation method comprising:
providing a positive electrode active material comprising lithium-containing transition metal phosphate particles, at least some surfaces of which are provided with a carbon coated material, wherein the positive electrode active material comprises a mixture of a first group of ground particles and a second group of ground particles, a volume median particle size D V50 of the first group of ground particles is 0.8 μm to 1.2 μm, a volume median particle size D V50 of the second group of ground particles is 0.30 μm to 0.5 μm, and a mass ratio of the first group of ground particles to the second group of ground particles is 60:40 to 80:20;
sequentially adding a binder, a conductive agent, and the positive electrode active material, dry mixing, adding a solvent, stirring, and adjusting a viscosity, to obtain a delivery slurry;
transfer-coating at least one side of a current collector with the delivery slurry, drying, and hot pressing, to obtain a positive electrode film layer;
wherein the drying is at a temperature ranging from 95° C. to 105° C. and a speed ranging from 2.0 m/min to 2.3 m/min,
wherein the hot pressing comprises at least three times of hot rolling with hot rolling pressures sequentially increased and sequentially ranging from 20 metric tons to 50 metric tons, 50 metric tons to 70 metric tons, and 70 metric tons to 90 metric tons, a hot rolling temperature ranges from 40° C. to 80° C., and before entering hot rolling for a first time, the electrode plate is heated at 40° C. to 50° C.,
wherein in a cross section of the positive electrode film layer in an electrode plate thickness direction, D A90 of particles ranges from 1400 nm to 2100 nm and (D A90 −D A10 )/D A50 ranges from 1.855 to 2.375.
20 . A lithium-ion secondary battery, comprising a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one side of the negative electrode current collector;
the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises lithium-containing transition metal phosphate particles and a titanium element, at least some surfaces of which are provided with a carbon coated material, and a mass content of the titanium element based on the total mass of the positive electrode active material ranges from 4000 ppm to 8000 ppm; and
the negative electrode film layer comprises a negative electrode active material, the negative electrode active material comprises artificial graphite;
wherein the positive electrode active material comprises a mixture of a first group of ground particles and a second group of ground particles, a volume median particle size D V50 of the first group of ground particles is 0.8 μm to 1.2 μm, a volume median particle size D V50 of the second group of ground particles is 0.30 μm to 0.45 μm, and a mass ratio of the first group of ground particles to the second group of ground particles is 60:40 to 80:20,
wherein in a cross section of the positive electrode film layer in an electrode plate thickness direction, D A90 of the particles ranges from 1400 nm to 2100 nm, D A50 of the particles in the cross section of the positive electrode film layer in the electrode plate thickness direction ranges from 708 nm to 785 nm, D A10 of the particles in the cross section of the positive electrode film layer in the electrode plate thickness direction ranges from 122 nm to 262 nm, and a particle size concentration ratio (D A90 −D A10 )/D A50 ranges from 1.855 to 2.375, wherein D A90 , D A50 , and D A10 refer to corresponding particle sizes of particles when area cumulative distributions of the particles reach 90%, 50%, and 10% in an area cumulative distribution curve of the particles,
wherein a graphitization degree C value cumulative distribution curve of the positive electrode film layer that is obtained in a laser micro-confocal Raman spectrometer surface scanning mode, a graphitization degree median C 50 ranges from 1.02 to 1.07; and a graphitization degree C value is IG/ID, wherein IG represents an intensity of a G peak at 1580±100 cm −1 of a Raman spectrum, and I D represents an intensity of a D peak at 1350±100 cm −1 of the Raman spectrum,
wherein in the sphericity area cumulative distribution curve of the particles that are obtained from the cross section of the positive electrode film layer in the electrode plate thickness direction, the sphericity median L A50 ranges from 0.709 to 0.751.