Method for preparing nickel-rich hydroxide precursor material and method for preparing nickel-rich oxide cathode material
The present disclosure provides the methods for preparing nickel-rich hydroxide precursor material and nickel-rich oxide cathode material having a homogeneous structure with an element concentration-gradient distribution by utilizing a continuous Taylor-flow reactor, comprising: (1) preparing an aqueous solution A with metal ion raw materials dissolved therein, an aqueous solution B with a manganese source dissolved therein, an aqueous solution C with a precipitant dissolved therein, and an aqueous solution D with a chelating agent dissolved therein; feeding the aqueous solution A, the aqueous solution C and the aqueous solution D into the continuous Taylor-flow reactor to perform a first co-precipitation reaction; (2) feeding the aqueous solution B into the continuous Taylor-flow reactor to perform a second co-precipitation reaction; (3) washing the precipitate obtained from the second co-precipitation reaction and putting the precipitate into an oven to dry the precipitate to fabricate the nickel-rich hydroxide precursor material. The nickel-rich hydroxide precursor material prepared with the method of the present disclosure exhibiting an element gradient distribution with the nickel-rich inner layer and the manganese-rich outer layer may reduce the diffusion impedance of the lithium ions and increase their migration paths, and the nickel-rich oxide cathode material prepared from the nickel-rich hydroxide precursor material may increase the electrochemical performances and mechanical stability of the lithium-ion cells, such as charging and discharging rate, long-term cycle life, etc.
1 . A method for preparing a nickel-rich hydroxide precursor material, which is a nickel cobalt manganese hydroxide having a homogeneous structure with an element concentration-gradient distribution, comprising:
(1) preparing an aqueous solution A with metal ion raw materials dissolved therein;
preparing an aqueous solution B with a manganese source dissolved therein;
preparing an aqueous solution C with a precipitant dissolved therein;
preparing an aqueous solution D with a chelating agent dissolved therein;
feeding the aqueous solution A, the aqueous solution C and the aqueous solution D into a continuous Taylor-flow reactor to perform a first co-precipitation reaction for 2 to 7 hours;
wherein the metal ion raw materials include a nickel source and a cobalt source;
wherein the nickel source is at least one selected from a group consisting of nickel sulfate, nickel oxalate, nickel acetate, nickel nitrate, nickel chloride, and nickel hydroxide;
the cobalt source is at least one selected from a group consisting of cobalt sulfate, cobalt oxalate, cobalt carbonate, cobalt acetate, cobalt nitrate, cobalt chloride, and cobalt hydroxide;
the manganese source is at least one selected from a group consisting of manganese sulfate, manganese oxalate, manganese carbonate, manganese citrate, manganese acetate, manganese nitrate, manganese phosphate, electrolytic manganese dioxide, and manganese oxide;
(2) feeding the aqueous solution B into the continuous Taylor-flow reactor to perform a second co-precipitation reaction for 5 to 70 hours to obtain a precipitate; wherein
the second co-precipitation reaction is performed with a reaction temperature of 30° C. to 80° C., an reaction pH value of 9.5 to 12.5, and a rotation speed of an inner cylinder in the continuous Taylor-flow reactor of 200 rpm to 1500 rpm;
(3) washing the precipitate obtained from the second co-precipitation reaction and putting the precipitate into an oven to dry the precipitate, to fabricate the nickel-rich hydroxide precursor material.
2 . The method for preparing the nickel-rich hydroxide precursor material of claim 1 , wherein the aqueous solution A has a concentration of 1.6 M to 1.92 M.
3 . The method for preparing the nickel-rich hydroxide precursor material of claim 1 , wherein the aqueous solution B has a concentration of 0.08 M to 0.4 M.
4 . The method for preparing the nickel-rich hydroxide precursor material of claim 1 , wherein the aqueous solution C has a concentration of 2.0 M to 6.0 M, and a weight molar concentration ratio of the aqueous solution A and aqueous solution C is 1:1 to 1:5.
5 . The method for preparing the nickel-rich hydroxide precursor material of claim 1 , wherein the aqueous solution D has a concentration of 2.5 M to 9.0 M, and a weight molar concentration ratio of the aqueous solution A and aqueous solution D is 1:1 to 1:5.
6 . The method for preparing the nickel-rich hydroxide precursor material of claim 1 , wherein the oven is operated with a drying temperature of 60° C. to 120° C. and a drying time of 6 to 24 hours.
7 . The method for preparing the nickel-rich hydroxide precursor material of claim 1 , wherein the aqueous solution A and the aqueous solution B are fed with a feeding rate of 1.0 to 3.0 ml/min.
8 . A method for preparing a nickel-rich oxide cathode material, comprising the method for preparing the nickel-rich hydroxide precursor material of claim 1 and:
(a) dispersing an aluminum source in ethanol, adding and mixing the nickel-rich hydroxide precursor material with the aluminum source in the ethanol to obtain a blend, heating the blend at a temperature of 80° C. until the blend is totally dried to obtain a mixture A;
wherein the aluminum source is at least one selected from a group consisting of aluminum hydroxide, aluminum oxalate, aluminum carbonate, aluminum sulfate, aluminum acetate, aluminum nitrate, and aluminum phosphate;
(b) milling and mixing a lithium source, and a molar ratio of the mixture A and the lithium source is 1:1.01 to 1:1.25 to obtain a mixture B;
the lithium source is at least one selected from a group consisting of lithium hydroxide, lithium nitrate, lithium acetate, lithium chloride, lithium hydrogen phosphate, lithium phosphate, and lithium carbonate;
(c) performing a three-stage calcination to the mixture B to fabricate the nickel-rich oxide cathode material.
9 . The method for preparing the nickel-rich oxide cathode material of claim 8 , wherein the lithium source and the mixture A are milled with a ball mill for 2 to 10 hours with a rotation speed of the ball milling being 50 to 200 rpm.
10 . The method for preparing the nickel-rich oxide cathode material of claim 8 , wherein the three-stage calcination is performed at: a temperature of 100° C. to 200° C. for 1 to 3 hours at a first stage; a temperature of 500° C. to 600° C. for 4 to 8 hours at a second stage; and a temperature of 700° C. to 800° C. for 10 to 40 hours at a third stage, wherein the first stage, the second stage and the third stage are performed with a heating rate of 0.1 to 20° C./min.