| CPC H01M 4/525 (2013.01) [H01M 4/131 (2013.01); H01M 4/1391 (2013.01); H01M 4/505 (2013.01); H01M 10/0525 (2013.01)] | 2 Claims |
|
1. A preparation method for a ternary precursor of a lithium ion battery, comprising steps of:
S1, preparing a nickel cobalt manganese metal salt solution having a concentration of 1.0-3.0 mol/L, an ammonia solution having a concentration of 6.0-12 mol/L, and a sodium hydroxide solution having a concentration of 4.0-10 mol/L;
S2, adding water into a reactor, introducing a protective gas into the reactor, adding the prepared nickel cobalt manganese metal salt solution, a precipitant solution and a complexing agent solution into the reactor, respectively, starting stirring, obtaining a stirring power consumption and a mixing time by monitoring a torque, a motor current, a rotation speed and a liquid level, and obtaining an energy dissipation circulation function (EDCF) through a reactor size, an impeller type and a blade size to characterize a shear action in the reactor, wherein the EDCF=(P/kD3)/tm, k=π/4/(W/D), P is power consumption, W is width of blades, D is a diameter of the impeller, and tm is the mixing time, and P=2πNTq, wherein N is a stirring rotation speed, Tq is a stirring torque, the mixing time tm=5.2Np−1/3(D/T)−2(HzT)α/N, Np is a power number of the impeller, T is a tank diameter, Hz is a liquid level height, and the power consumption P is obtained by measuring the torque, P=ρNpN3D5, in which ρ is a solution density, and an index α is obtained by calculating the mixing time obtained by a conductivity method or a pH value method:
S3, controlling a reaction temperature to be 40-70° C., a pH value to be 10.5-12.5 and an ammonia concentration to be 2.0-12 g/L, controlling the EDCF to be 0.05-65 kW/(m3·s), and stopping the reaction until crystalline particles reach the standard to prepare a large-particle ternary precursor slurry or a small-particle ternary precursor slurry,
when preparing the large-particle ternary precursor slurry, the step S3 comprises steps of:
S311, controlling the reaction temperature to be 40-70° C., the pH value to be 10.5-12.5 and the ammonia concentration to be 2.0-12 g/L, controlling the EDCF to be 30-45 kW/(m3·s);
S312, when a feed liquid reaches an overflow port, enabling the feed liquid to overflow into a concentrator for concentration, returning the concentrated slurry to the reactor through a reflux port for continuous reaction, and discharging a mother liquor from the reactor;
S313, when a solid content of the crystalline particles reaches 100-400 g/L, controlling the EDCF to be 10-30 kW/(m3·s); when the solid content of the crystalline particles reaches 300-600 g/L, controlling the EDCF to be 1.0-10 kW/(m3·s); when the solid content of the crystalline particles reaches 500-1000 g/L, controlling the EDCF to be 0.05-0.5 kW/(m3·s);
S314, continuing to control the pH value, the ammonia concentration and the temperature in the reaction process, stopping the reaction when the particle size D50 reaches 10.0-16.0 μm, and obtaining the large-particle ternary precursor slurry:
or when preparing the small-particle ternary precursor slurry, the step S3 comprises steps of:
S321, controlling the reaction temperature to be 40-70° C., the pH value to be 10.5-12.5 and the ammonia concentration to be 2.0-12 g/L, controlling the EDCF to be 45-65 kW/(m3·s):
S322, when the feed liquid reaches an overflow port, enabling the feed liquid to overflow into the concentrator for concentration, returning the concentrated slurry to the reactor through the reflux port for continuous reaction, and discharging the mother liquor from the reactor;
S323, when the solid content of the crystalline particles reaches 100-400 g/L, controlling the EDCF to be 40-55 kW/(m3·s); when the solid content of the crystalline particles reaches 300-600 g/L, controlling the EDCF to be 25-40 kW/(m3·s); when the solid content of the crystalline particles reaches 500-1000 g/L, controlling the EDCF to be 15-35 kW/(m3·s);
S324, continuing to control the pH value, the ammonia concentration and the temperature in the reaction process, stopping the reaction when the particle size D50 reaches 3.0-6.0 μm, and obtaining the small-particle ternary precursor slurry;
S4, carrying out solid-liquid separation, washing, drying and sieving on the ternary precursor slurry to obtain the ternary precursor of cathode materials for the lithium ion battery, wherein a preparation device for preparing the ternary precursor of the lithium ion battery comprises:
a reactor provided with a liquid inlet and an inner chamber, wherein the liquid inlet is connected with the inner chamber and an outside world, and the liquid inlet is provided on an upper part of the reactor;
a stirring drive system comprising a motor, a reducer and a stirring mechanism, wherein the reducer is connected to the motor and the stirring mechanism, the stirring mechanism is installed in the inner chamber of the reactor and comprises a stirring shaft and at least one turbine impeller, the stirring shaft is rotatably connected to the reducer and the turbine impeller that comprises a plurality of blades and a disc, the disc is connected to the stirring shaft, the blades extend outwards from a peripheral side of the disc obliquely in an arc, and a tilt angle of the blades is 30-80°; the blades each comprise a main blade and a secondary blade, one end of the main blade is fixedly connected to the disc, and the secondary blade extends outward from the other end of the main blade in the direction of an arc surface, wherein the secondary blade is in a sine curve, y=A sin ωx, an amplitude A is 0.1-1.0 times of the width of the blade, a period T=2π/ω, having a range of 1-3, and a length of the secondary blade accounts for 10%-50% of a total length of the blade, wherein each turbine impeller further comprises a hub and a plurality of connection plates, the hub is located in the middle of the disc and is fixedly connected to the stirring shaft, and the connection plates are evenly distributed along the periphery of the disc, so that the main blades are obliquely fixed to the connection plates, wherein the length of the blade accounts for 10%-40% of a diameter of the turbine impeller, a ratio of the diameter of the turbine impeller to a diameter of the reactor is 0.3-0.6:1, the reactor is internally provided with at least two layers of turbine impellers, each of the turbine impellers comprises 4-8 blades, and a ratio of a layer spacing between the turbine impellers to the diameter of the turbine impeller is 0.6-1.5:1;
a concentrator, a torque sensor and a tachometer, wherein the torque sensor and the tachometer are respectively connected to the stirring shaft, the reactor is further provided with a first liquid inlet, a second liquid inlet, a third liquid inlet, an overflow port and a reflux port; the first liquid inlet and the second liquid inlet are staggered at an upper part of the reactor, the first liquid inlet and the third liquid inlet are provided on the same side, the first liquid inlet is used for introducing an ammonia solution, the third liquid inlet is used for introducing a nickel cobalt manganese metal salt solution, the second liquid inlet is used for introducing an alkali solution, and a stagger angle between the first liquid inlet and the second liquid inlet is 90°-180°; the overflow port and the reflux port are spaced at a side of the reactor, the overflow port is higher than the reflux port, and the concentrator is respectively connected with the overflow port and the reflux port, wherein the overflow port is located at a position 0.80-0.85 times the height of a straight section of the reactor.
|