CN104466154B - A kind of preparation method of lithium ion battery anode material nickel cobalt aluminium - Google Patents

Abstract

The invention discloses a preparation method of nickel-cobalt-aluminum anode material of lithium ion battery, which comprises the following steps: mixing nickel, cobalt and aluminum salt solutions, and then co-flowing a precipitating agent, a complexing agent and the above-mentioned mixed solution of nickel-cobalt-aluminum Add it into the reaction kettle for co-precipitation reaction, adjust the pH value of the system to 10~11, the temperature is 40~60°C, the stirring speed is 500~1500 rpm, and after reacting for 10~30 h, filter, wash, and dry. The hydroxide precursor is obtained; the precursor is pre-sintered at high temperature to obtain nickel-cobalt-aluminum oxide, then mixed with lithium source, sintered at high temperature in an oxygen atmosphere, and nickel-cobalt-aluminum powder is obtained after crushing and sieving. By calculating the pre-sintering loss rate of the precursor, and using XPS to analyze the contents of Ni ²⁺ and Ni ³⁺ in nickel-cobalt-aluminum oxides at different pre-sintering temperatures, the nickel-cobalt-aluminum oxide with the highest Ni ³⁺ content was obtained to promote In the secondary sintering process, more nickel ions are converted into Ni ³⁺ , reducing the mixing of Li ⁺ and Ni ²⁺ , and improving the electrochemical performance of the material.

Description

A kind of preparation method of nickel-cobalt-aluminum anode material of lithium ion battery

technical field

The invention relates to the fields of energy storage materials and electrochemistry, in particular to a preparation method of nickel-cobalt-aluminum cathode material for lithium ion batteries.

Background technique

Since the Japanese SONY company first successfully developed and commercialized lithium-ion batteries in 1991, lithium-ion batteries have attracted more and more attention because of their light weight, small size, high specific energy, small self-discharge, and good cycle performance. With the characteristics of low pollution and no memory effect, it has become one of the most promising green secondary batteries in the 21st century. With the development of electrode materials, battery cathode materials with their own characteristics have emerged one after another, such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, and nickel-cobalt-manganese ternary materials. At present, lithium-ion batteries are widely used in many fields such as national defense industry, space technology, portable electronic equipment and electric vehicles, so people have higher and higher requirements for lithium-ion batteries, such as good safety performance, high specific capacity, cycle performance Excellent, light weight and small size, etc., but the current mature battery materials are difficult to meet the above properties at the same time. LiNi _1-xy Co _x A1 _y O ₂ (NCA) is currently the cathode material with the highest specific capacity that has been industrially applied. It has the advantages of good cycle performance, abundant raw materials and low cost. It is a promising lithium ion Power battery cathode material.

At present, the synthesis methods of ternary materials LiNi _1-xy Co _x A1 _y O ₂ mainly include coprecipitation method, high temperature solid phase method, sol-gel method, molten salt method, spray drying method, microwave method, hydrothermal method and combustion method, etc., but the LiNi _{1-x- y} Co _x A1 _y O ₂ materials prepared by each method still have some shortcomings and need to be further improved. Among them, the co-precipitation method is simple to operate, and the performance of the synthesized material is the best, and it is a method with the most industrial application prospects.

In the prior art, when preparing nickel-cobalt-aluminum cathode material for lithium-ion batteries, nickel-cobalt-aluminum hydroxide precursor is prepared by co-precipitation, mixed with lithium source directly or mixed with lithium source after high-temperature pre-sintering, and then undergoes high-temperature sintering and subsequent crushing treatment A nickel-cobalt-aluminum cathode material is obtained. Nickel cobalt aluminum hydroxide compound, mainly nickel hydroxide decomposes above 230°C to form NiO. When the temperature reaches 400°C, part of NiO absorbs air and oxidizes into Ni ₂ O ₃ . Finally, when the temperature is higher than 600°C , Ni ₂ O ₃ is reduced to low-activity NiO; in addition, if the content of divalent nickel in nickel-cobalt-aluminum oxide is too high, the subsequent sintering process cannot be completely oxidized to trivalent nickel, and the radius of divalent nickel is very close to that of lithium ions. It is easy to produce mixing phenomenon and affect the electrochemical performance of the material. Therefore, precursors with different Ni ²⁺ and Ni ³⁺ contents can be obtained by pre-sintering at different temperatures, and the electrochemical properties of the final materials are different.

Contents of the invention

The problem to be solved by the present invention is to improve a preparation method of nickel-cobalt-aluminum cathode material for lithium-ion batteries. Ignition loss rate, and use X-ray photoelectron spectroscopy (XPS) to analyze the content of Ni ²⁺ and Ni ³⁺ , and obtain the nickel-cobalt-aluminum oxide with the highest Ni ³⁺ content, which can promote more nickel ion conversion in the secondary sintering process For Ni ³⁺ , reduce the mixing of Li ⁺ and Ni ²⁺ , and prepare nickel-cobalt-aluminum cathode material with good electrochemical performance.

In order to solve the above-mentioned technical problems, the technical solution of the present invention is: a preparation method of nickel-cobalt-aluminum anode material for lithium ion battery, comprising the following steps:

(1) Preparation of nickel-cobalt-aluminum precursor: Mix nickel salt solution, cobalt salt solution and aluminum salt solution. The complexing agent solution and the above-mentioned mixed solution of nickel-cobalt-aluminum flow together through a constant-flow pump and add them into the reactor equipped with bottom liquid for co-precipitation reaction, control the pH value and temperature, and filter after stirring for 10~30h. Washing and drying to obtain the nickel-cobalt-aluminum hydroxide precursor of the positive electrode material of the lithium-ion battery;

(2) Preparation of nickel-cobalt-aluminum cathode material: the nickel-cobalt-aluminum oxide obtained after high-temperature pre-sintering of the precursor was calculated for the loss on ignition rate after high-temperature pre-sintering and the contents of Ni ²⁺ and Ni ³⁺ were analyzed by XPS, and then Mixed with lithium source, sintered at high temperature under oxygen atmosphere, crushed and sieved to obtain nickel-cobalt-aluminum powder, which is the positive electrode material of lithium-ion battery.

In the present invention, the content of Ni ²⁺ and Ni ³⁺ in the nickel-cobalt-aluminum oxide obtained at different pre-sintering temperatures is obtained by calculating the loss on ignition rate of the pre-sintering of the precursor, and using X-ray photoelectron energy spectroscopy to obtain the nickel with the most Ni ³⁺ content. Cobalt aluminum oxide can promote the conversion of more nickel ions into Ni ³⁺ in the secondary sintering process, reduce the mixing of Li ⁺ and Ni ²⁺ , and improve the electrochemical performance of the material.

In the above-mentioned preparation method of nickel-cobalt-aluminum positive electrode material for lithium-ion batteries, the nickel salt, cobalt salt and aluminum salt are preferably nitrates, according to the Ni:Co:Al molar ratio of 0.80:0.15:0.05;

In the preparation method of the above-mentioned lithium-ion battery positive electrode material nickel-cobalt-aluminum, the described precipitating agent is preferably a sodium hydroxide solution of 1mol/L～5mol/L;

In the preparation method of above-mentioned lithium-ion battery cathode material nickel-cobalt-aluminum, described complexing agent is preferably the ammoniacal solution of 4～10mol/L;

In the preparation method of above-mentioned lithium-ion battery cathode material nickel-cobalt-aluminum, described bottom liquid is preferably the ammoniacal solution of 4～10mol/L;

In the above-mentioned preparation method of nickel-cobalt-aluminum cathode material for lithium-ion batteries, the pH value in the step (1) is preferably 10-11;

In the above-mentioned preparation method of nickel-cobalt-aluminum anode material for lithium-ion batteries, the temperature in the step (1) is preferably 40-60°C;

In the above-mentioned preparation method of nickel-cobalt-aluminum cathode material for lithium-ion batteries, the stirring speed in the step (1) is preferably 500-1500 rpm;

In the above-mentioned preparation method of nickel-cobalt-aluminum cathode material for lithium-ion batteries, the pre-sintering in the step (2) is preferably 500-750°C for 2-8 hours, and the heating rate is 1-6°C/min;

In the above-mentioned preparation method of nickel-cobalt-aluminum cathode material for lithium-ion batteries, the sintering in the step (2) is preferably 750-850°C for 10-20h, and the heating rate is 1-6°C/min;

In the above-mentioned preparation method of nickel-cobalt-aluminum cathode material for lithium-ion batteries, the molar ratio of nickel-cobalt-aluminum oxide to lithium source in the step (2) is preferably 1: (1~1.05);

In the above-mentioned preparation method of lithium-ion battery cathode material nickel-cobalt-aluminum, the lithium source in the step (2) is preferably lithium hydroxide, lithium carbonate, lithium nitrate, lithium sulfate, lithium oxalate, lithium acetate, lithium chloride one or more of

In the above-mentioned preparation method of nickel-cobalt-aluminum anode material for lithium ion battery, the analysis method of Ni ²⁺ and Ni ³⁺ content in the step (2) is preferably loss-of-ignition rate and X-ray photoelectron spectroscopy analysis method.

Compared with the prior art, the nickel-cobalt-aluminum cathode material of the lithium ion battery prepared by the method of the present invention has the following beneficial effects:

(1) When pre-sintering at the optimal temperature, the precursor can be completely decomposed, and the low-activity Ni ²⁺ content in the obtained nickel-cobalt-aluminum oxide is small, which improves the electrochemical performance of the material;

(2) After pre-sintering at the optimal temperature, the precursor oxide with the highest Ni ³⁺ content is obtained, which reduces the mixing of Li ⁺ and Ni ²⁺ in the material during secondary sintering, and improves the electrochemical performance of the material;

(3) The synthetic material has high reversible specific capacity and good cycle stability. In the range of 2.5~4.3V, the discharge specific capacity is greater than 170mAh/g.

Description of drawings

Fig. 1 is the XRD spectrum of the nickel-cobalt-aluminum oxide after the pre-sintering of embodiment 1;

Fig. 2 is the XPS collection of illustrative plates of nickel-cobalt-aluminum oxide after the pre-sintering of embodiment 1;

Fig. 3 is the first charge-discharge curve of the product of embodiment 1;

Fig. 4 is the cycle performance figure of the product of embodiment 1;

Fig. 5 is the XRD spectrum of the nickel-cobalt-aluminum oxide after pre-sintering of embodiment 2;

Fig. 6 is the XPS collection of illustrative plates of nickel-cobalt-aluminum oxide after the pre-sintering of embodiment 2;

Fig. 7 is the first charge-discharge curve of the product of embodiment 2;

Fig. 8 is the cycle performance figure of the product of embodiment 2;

Fig. 9 is the XRD spectrum of the nickel-cobalt-aluminum oxide after pre-sintering of embodiment 3;

Fig. 10 is the XPS collection of illustrative plates of nickel-cobalt-aluminum oxide after the pre-sintering of embodiment 3;

Fig. 11 is the first charge-discharge curve of the product of embodiment 3;

FIG. 12 is a cycle performance graph of the product of Example 3.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

Using nickel nitrate, cobalt nitrate and aluminum nitrate as raw materials, according to the Ni:Co:Al molar ratio of 0.8:0.15:0.05, prepare a 1mol/L mixed solution, mix the mixed solution with 2mol/L sodium hydroxide solution and 6mol/L L of ammonia solution is fed into a 2L reaction kettle in parallel through a constant flow pump. The reaction kettle contains 600mL of ammonia solution with a pH value of 10.5 and a temperature of 50°C as the bottom liquid, and the stirring speed is 600 rpm for precipitation. During the reaction, the fluctuation of pH value shall not exceed ±0.4, and the fluctuation of temperature shall not exceed ±1°C. After the precipitation reaction is complete, filter and wash several times until the pH value of the filtrate is close to 7, and the nitrate content in the filtrate is less than 1×10 ^-5 mol/L, dried under vacuum at 120°C to obtain grass-green nickel-cobalt-aluminum hydroxide precursor;

The nickel-cobalt-aluminum precursor prepared in the above steps is pre-fired in a tubular resistance furnace at 750°C for 2 hours, and the heating rate is 5°C/min to obtain nickel-cobalt-aluminum oxide, which is then mixed with lithium hydroxide at a molar ratio of 1:1.05 Evenly, put it in a tubular resistance furnace in an oxygen atmosphere and sinter at 800°C for 12h, with a heating rate of 5°C/min. After cooling, it is crushed and sieved to obtain nickel-cobalt-aluminum powder, a cathode material for lithium-ion batteries.

After testing, the loss on ignition rate of the high-temperature pre-sintering of the precursor in this embodiment is 8.88%. The first discharge specific capacity of the battery is 161mAh/g, as shown in Figure 3, and the capacity retention rate after 50 cycles is 92.75%, as shown in Figure 4.

Example 2

Using nickel nitrate, cobalt nitrate and aluminum nitrate as raw materials, according to the Ni:Co:Al molar ratio of 0.8:0.15:0.05, prepare a 2mol/L mixed solution, mix the mixed solution with 5mol/L sodium hydroxide solution and 10mol/L L of ammonia solution is fed into a 2L reaction kettle in parallel through a constant flow pump. The reaction kettle contains 600mL of ammonia solution with a pH value of 11.0 and a temperature of 60°C as the bottom liquid, and the stirring speed is 1000 rpm for precipitation. During the reaction, the fluctuation of pH value shall not exceed ±0.4, and the fluctuation of temperature shall not exceed ±1°C. After the precipitation reaction is complete, filter and wash several times until the pH value of the filtrate is close to 7, and the nitrate content in the filtrate is less than 1×10 ^-5 mol/L, dried under vacuum at 120°C to obtain grass-green nickel-cobalt-aluminum hydroxide precursor;

The nickel-cobalt-aluminum precursor prepared in the above steps was pre-fired in a tubular resistance furnace at 650°C for 4 hours, and the heating rate was 5°C/min to obtain nickel-cobalt-aluminum oxide, which was then mixed with lithium hydroxide at a molar ratio of 1:1.05 Evenly, put it in a tubular resistance furnace in an oxygen atmosphere and sinter at 800°C for 12h, with a heating rate of 5°C/min. After cooling, it is crushed and sieved to obtain nickel-cobalt-aluminum powder, a cathode material for lithium-ion batteries.

After testing, the loss on ignition rate of the high-temperature pre-sintering of the precursor in this embodiment is 5.97%. The X-ray diffraction pattern and X-ray photoelectron spectrum of the precursor oxide are shown in Figure 5 and Figure 6, respectively. The first discharge specific capacity of the formula battery is 174mAh/g, as shown in Figure 7, and the capacity retention rate after 50 cycles is 94.04%, as shown in Figure 8.

Implementation Case 3

Using nickel nitrate, cobalt nitrate and aluminum nitrate as raw materials, according to the Ni:Co:Al molar ratio of 0.8:0.15:0.05, prepare a 1mol/L mixed solution, mix the mixed solution with 2mol/L sodium hydroxide solution and 6mol/L L of ammonia solution is fed into a 2L reaction kettle in parallel through a constant flow pump. The reaction kettle contains 600mL of ammonia solution with a pH value of 10.5 and a temperature of 60°C as the bottom liquid, and the stirring speed is 750 rpm for precipitation. During the reaction, the fluctuation of pH value shall not exceed ±0.4, and the fluctuation of temperature shall not exceed ±1°C. After the precipitation reaction is complete, filter and wash several times until the pH value of the filtrate is close to 7, and the nitrate content in the filtrate is less than 1×10 ^-5 mol/L, dried under vacuum at 120°C to obtain grass-green nickel-cobalt-aluminum hydroxide precursor;

The nickel-cobalt-aluminum precursor prepared in the above steps was pre-fired in a tubular resistance furnace at 500°C for 6 hours, and the heating rate was 5°C/min to obtain nickel-cobalt-aluminum oxide, and then mixed with lithium hydroxide at a molar ratio of 1:1.05 Evenly, put it in a tubular resistance furnace in an oxygen atmosphere and sinter at 800°C for 12h, with a heating rate of 5°C/min. After cooling, it is crushed and sieved to obtain nickel-cobalt-aluminum powder, a cathode material for lithium-ion batteries.

After testing, the loss on ignition rate of the high-temperature pre-sintering of the precursor in this example is 7.33%. The first discharge specific capacity of the battery is 171mAh/g, as shown in Figure 11, and the capacity retention rate after 50 cycles is 93.54%, as shown in Figure 12.

Claims (11)

1. A preparation method for lithium-ion battery cathode material nickel-cobalt-aluminum, comprising the following steps: (1) Preparation of nickel-cobalt-aluminum precursor: Mix nickel salt solution, cobalt salt solution and aluminum salt solution. The mixed solution of the complexing agent solution and the above-mentioned nickel-cobalt-aluminum is fed into the reaction kettle equipped with the bottom liquid through a constant flow pump to carry out the co-precipitation reaction, and the pH value and temperature are controlled. After stirring for 10-30 hours, filter and wash for many times , dried to obtain the lithium-ion battery cathode material nickel cobalt aluminum hydroxide precursor; (2) Preparation of nickel-cobalt-aluminum cathode material: pre-sintering the precursor at different temperatures to obtain nickel-cobalt-aluminum oxide, analyzing the content of Ni ²⁺ and Ni ³⁺ in the nickel-cobalt-aluminum oxide, and the content of Ni ³⁺ is the highest The nickel-cobalt-aluminum oxide is mixed with the lithium source, sintered at high temperature in an oxygen atmosphere, and after crushing and screening, the nickel-cobalt-aluminum powder, which is the positive electrode material of the lithium-ion battery, is obtained; The complexing agent in the step (1) is an aqueous ammonia solution of 4 to 10mol/L; In the step (2), the pre-sintering temperature is 500-750° C., the heating rate is 1-6° C./min, and the holding time is 2-8 hours. 2. the preparation method of lithium-ion battery cathode material nickel-cobalt-aluminum according to claim 1 is characterized in that: nickel salt, cobalt salt and aluminum salt in described step (1) are all nitrates, according to Ni:Co :Al molar ratio 0.80:0.15:0.05. 3. The preparation method of nickel-cobalt-aluminum anode material for lithium ion battery according to claim 1, characterized in that: the precipitating agent in the step (1) is 1mol/L-5mol/L sodium hydroxide solution. 4. The preparation method of nickel-cobalt-aluminum anode material for lithium ion battery according to claim 1, characterized in that: the bottom liquid in the step (1) is 4-10 mol/L ammonia solution. 5. The preparation method of nickel-cobalt-aluminum anode material for lithium ion battery according to claim 1, characterized in that: the pH in the step (1) is 10-11. 6 . The preparation method of nickel-cobalt-aluminum anode material for lithium ion battery according to claim 1 , characterized in that: the precipitation reaction temperature in the step (1) is 40-60° C. 7. The preparation method of nickel-cobalt-aluminum anode material of lithium ion battery according to claim 1, characterized in that: the stirring speed in the precipitation reaction process of the step (1) is 500-1500 rpm. 8. The preparation method of nickel-cobalt-aluminum anode material for lithium ion battery according to any one of claims 1-7, characterized in that: the sintering temperature in the step (2) is 750-850° C., and the heating rate is 1 ~6°C/min, holding time is 10~20h. 9. according to the preparation method of lithium-ion battery cathode material nickel-cobalt-aluminum described in any one in claim 1～7, it is characterized in that: the mol ratio of nickel-cobalt-aluminum oxide and lithium source in described step (2) is 1: (1~1.05). 10. according to the preparation method of lithium-ion battery cathode material nickel-cobalt-aluminum described in any one in the claim 1～7, it is characterized in that: lithium source is lithium hydroxide, lithium carbonate, lithium nitrate in described step (2) , one or more of lithium sulfate, lithium oxalate, lithium acetate, lithium chloride. 11. The method for preparing the lithium-ion battery cathode material nickel-cobalt-aluminum according to any one of claims 1 to 7, characterized in that: the content detection method of Ni ²⁺ and Ni ³⁺ in the step (2) is Calculation of loss of ignition rate and X-ray photoelectron spectroscopy analysis method.