CN103991908A - Method for regulating and controlling stability of lithium ion sieve by cation doping - Google Patents

Abstract

The invention discloses a method for regulating the stability of a lithium ion sieve through cation doping, comprising preparing a composite oxide Li ₄ Mn _x R _y O ₁₂ , wherein the doping ions R are Sn, Zr, Ti, Fe, Ni, Co Or Al, and 2.5≤x≤4.996, 0.004≤y≤2.5, x+y is 5, the preparation includes: (1) mixing divalent manganese salt, lithium salt and R-containing compound, making the dopant ion R/ The manganese/lithium molar ratio is (0.625～0.001):(0.625～1.249):1.00, and the (R+manganese)/lithium molar ratio is 1.1～1.5; (2) the mixture obtained in step (1) is heated at 350～650° C. Calcining for 6-120 hours under dynamic air conditions to obtain the composite oxide. Also provided is a method for preparing the ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O, wherein the composite oxide is washed with water, dried, and then Li ⁺ is leached out through a leaching agent. The invention has simple process route, mild preparation conditions and short reaction period, and the obtained cubic phase ion sieve has stable structure and high adsorption capacity.

Description

A method for regulating the stability of lithium-ion sieves by cation doping

technical field

The invention relates to a method for regulating the stability of lithium ion sieves by cation doping, in particular to a method for preparing Li ₄ Mn _x R _y O ₁₂ composite oxides (wherein R=Sn, Zr, Ti, Fe, Ni, Co, or Al) and manganese ion sieve adsorbent Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O.

Background technique

The special physicochemical properties of lithium are widely used in many fields. Efficiently extracting lithium from salt lakes or seawater is an important solution to the lithium shortage in the world today.

my country is a resource-rich country, and liquid lithium resources are very rich. However, low-grade brine or seawater is the main form of liquid lithium resources in my country. The methods for extracting and separating lithium from salt lake brine mainly include precipitation method and solvent extraction method. However, these traditional separation and extraction methods are not suitable for extracting lithium from low-grade brine or seawater, especially brine with a very high ratio of magnesium to lithium. The adsorption method has greater advantages than other methods no matter from the environmental point of view or from the economic point of view, especially the advantage of extracting lithium from low-grade brine or seawater is more obvious. The key to the adsorption method is to develop an adsorbent with excellent performance, which requires the adsorbent to have a high selectivity for lithium in order to eliminate the interference of a large number of coexisting ions in brine. Spinel-type manganese dioxide has a unique three-dimensional internal tunnel, which is conducive to the intercalation and extraction of Li ⁺ , so it is widely used as an electrode material and adsorbent for lithium batteries.

MnO ₂ ·0.31H ₂ O is a manganese dioxide ion sieve with long research time, high adsorption capacity and relatively stable performance.

The MnO ₂ ·0.31H ₂ O ion sieve obtained by pickling the cubic Li ₄ Mn ₅ O ₁₂ composite oxide is favored in the The field of Li-ion sieves has been extensively studied. Although the ion sieve should only have Mn ⁴⁺ theoretically, there should be no manganese dissolution loss. However, in the actual preparation process, it is difficult to oxidize all manganese to tetravalent, resulting in the occurrence of manganese dissolution loss in the pickling process.

Contents of the invention

The present invention provides a simple method of doping metal ions into the cubic phase Li ₄ Mn ₅ O ₁₂ , mainly using tetravalent metal ions with stronger bonds with oxygen or metals with a valence lower than tetravalent. Doping, so as to stabilize the crystal structure or increase the valence state of manganese to reduce the amount of manganese dissolution loss in the acidic process. At the same time, the effect of doping on the amount of lithium ion adsorption was studied.

The method for regulating the stability of a lithium ion sieve by cationic doping of the present invention includes preparing a lithium ion sieve precursor composite oxide Li ₄ Mn _x R _y O ₁₂ , wherein the dopant ion R is Sn, Zr, Ti, Fe, Ni, Co, or Al, and 2.5≤x≤4.996, 0.004≤y≤2.5, x+y is 5.0, the preparation of the composite oxide Li ₄ Mn _x R _y O ₁₂ includes: (1) divalent manganese Salt, lithium salt and R-containing compound are mixed so that the dopant ion R/manganese/lithium molar ratio is (0.625～0.001):(0.625～1.249):1.00, and the (R+manganese)/Li molar ratio is 1.1～1.5 (2) calcining the mixture obtained in step (1) at 350-650° C. under dynamic air conditions for 6-120 hours to obtain the composite oxide.

The method for regulating the stability of a lithium ion sieve by cation doping in the present invention comprises: washing and drying the complex oxide Li ₄ Mn _x R _y O ₁₂ described in the present invention, and then leaching Li through a lixiviating agent to obtain the Cation-doped lithium ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O.

The present invention also provides a composite oxide Li ₄ Mn _x R _y O ₁₂ , wherein the dopant ion R is Sn, Zr, Ti, Fe, Ni, Co, or Al, and 2.5≤x≤4.996, 0.004≤y ≤2.5, x+y is 5.0.

The present invention also provides a cation-doped lithium ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O, wherein the dopant ion R is Sn, Zr, Ti, Fe, Ni, Co, or Al, And 2.5≤x≤4.996, 0.004≤y≤2.5, x+y is 5.0.

Compared with the prior art, the present invention has the following beneficial effects:

1. The raw materials are cheap and easy to obtain, the molar ratio of lithium and manganese used is low, and the waste of lithium-containing raw materials is small;

2. The calcination temperature used is relatively low, which can reach 350°C, and the calcination time can be as short as 6 hours, and the obtained product has a single component and a uniform particle size;

3, the synthetic method of the present invention, experimental condition, product ratio are easy to control, and the condition range that can obtain ideal product is wide; And

4. The cubic phase Li ₄ Mn _x R _y O ₁₂ synthesized by the present invention has a spinel structure and stable properties; the synthesized ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O has manganese The dissolution loss is small, the lithium adsorption capacity is large, and the stability is good. It can be used to extract lithium from lithium-containing solutions such as salt lake brine and seawater.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is the XRD diagram of the cubic phase Li ₄ Mn _4.75 Ti _0.25 O ₁₂ synthesized in Example 1, wherein the X-ray diffractometer scans the entire diffraction area at an angle of 2θ;

Fig. 2 is the SEM picture of Li ₄ Mn _4.75 Ti _0.25 O ₁₂ synthesized in Example 1;

Fig. 3 is the XRD pattern of Li ₄ Mn _4.5 Ti _0.5 O ₁₂ synthesized in Example 2, wherein the X-ray diffractometer scans the entire diffraction area at an angle of 2θ;

Figure 4 is the XRD pattern of the ion sieve Mn _0.95 Ti _0.05 O ₂ ·0.31H ₂ O synthesized in Example 6, wherein the X-ray diffractometer scans the entire diffraction area at an angle of 2θ;

Fig. 5 is the SEM image of the ion sieve Mn _0.95 Ti _0.05 O ₂ ·0.31H ₂ O synthesized in Example 6;

Figure 6 is the XRD pattern of the ion sieve Mn _0.98 Co _0.02 O ₂ ·0.31H ₂ O synthesized in Example 7, wherein the X-ray diffractometer scans the entire diffraction area at an angle of 2θ;

Fig. 7 is the SEM image of the ion sieve Mn _0.98 Al _0.02 O ₂ ·0.31H ₂ O synthesized in Example 8;

Figure 8 is the XRD pattern of the ion sieve Mn _0.98 Ni _0.02 O ₂ ·0.31H ₂ O synthesized in Example 9, wherein the X-ray diffractometer scans the entire diffraction area Mn _0.98 Ni _0.02 O ₂ ·0.31H ₂ O at an angle of 2θ .

Detailed ways

The purpose of the present invention is to obtain a more stable structure or manganese closer to tetravalent by doping into the cubic phase Li ₄ Mn ₅ O ₁₂ positive tetravalent metal ions or metal ions with a valence lower than four which have a stronger interaction with oxygen. Cubic phase Li ₄ Mn _x R _y O ₁₂ and Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O ion sieves, thereby further reducing the amount of manganese dissolution in the Li ₄ Mn ₅ O ₁₂ pickling process and improving the corresponding The adsorption capacity of ion sieves for lithium ions. The present invention provides a method for preparing Li ₄ Mn _x R _y O ₁₂ (wherein R is Sn, Zr, Ti, Fe, Ni, Co or Al, and 2.5≤x≤4.996, 0.004≤y≤2.5) and Mn _x/5 Simple method for R _y/5 O ₂ ·0.31H ₂ O ion sieves. The present invention uses cheap and easy-to-obtain manganese salts, lithium salts, and compounds with metal ions R to obtain cubic phase Li ₄ Mn _x R _y O ₁₂ composite oxides through low-temperature calcination; then acid treatment is performed on the precursors to extract the Li , and then washed, filtered, and dried to obtain an adsorbent that has a screening effect on lithium ions; that is to say, the present invention uses a relatively simple process route to synthesize an ion sieve adsorbent with high adsorption capacity and good stability. The cubic phase Li ₄ Mn _x Ry _{O 12} ternary composite oxide of the present invention is suitable as an electrode material for a lithium battery. The ion sieve adsorbent Mn _x/5 R _y5 O ₂ ·0.31H ₂ O of the present invention is particularly suitable for enrichment and extraction from solutions containing low lithium and high concentrations of impurities (such as: salt lake brine, well water, seawater and other lithium-containing solutions) lithium.

Method for preparing lithium ion sieve precursor composite oxide Li ₄ Mn _x R _y O ₁₂ , wherein the dopant ion R is Sn, Zr, Ti, Fe, Ni, Co, or Al, and 2.5≤x≤4.996, 0.004 ≤y≤2.5, x+y is 5.0, including: (1) mixing divalent manganese salt, lithium salt and R-containing compound, so that the dopant ion R/manganese/lithium molar ratio is (0.625～0.001):( 0.625～1.249): 1.00, and the molar ratio of (R+manganese)/Li is 1.1～1.5; (2) calcining the mixture obtained in step (1) at 350～650°C under dynamic air conditions for 6～120h to obtain the composite oxide.

Preferably, the divalent manganese salt is manganese carbonate, manganese sulfate, manganese fluoride, manganese chloride, manganese iodide or a combination thereof.

Preferably, the lithium salt is lithium nitrate, lithium carbonate, lithium sulfate, lithium phosphate, lithium hydroxide, lithium chloride or a combination thereof.

Preferably, the compound containing R is tin dioxide, zirconium dioxide, zirconium sulfate, zirconium chloride, zirconium nitrate, titanium dioxide, titanium sulfate, n-butyl titanate, iron nitrate, iron hydroxide, iron sulfate, oxide Iron, ferric chloride, nickel hydroxide, nickel sulfate, nickel nitrate, nickel chloride, nickel oxide, cobalt nitrate, cobalt sulfate, cobalt carbonate, cobalt hydroxide, tricobalt tetroxide, aluminum nitrate, aluminum sulfate, aluminum hydroxide, trioxide Dialuminum or combinations thereof.

Preferably, the molar ratio of R/manganese/lithium is (0.01-0.16):(1.24-1.09):1, the mixing is carried out in water, and the moisture is removed before the calcination in step (2).

Preferably, the molar ratio of R/manganese/lithium in step (1) is (0.07～0.16):(1.17～1.09):1, and the temperature of calcination in step (2) is 350～450°C, and the time is 12～ 72h.

The preparation of the lithium ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O of the present invention includes washing and drying the composite oxide Li ₄ Mn _x R _y O ₁₂ , and then leaching Li through a lixiviating agent to obtain the The cation-doped lithium ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O.

Preferably, the leaching agent is 0.1-1 mol/L hydrochloric acid, sulfuric acid, nitric acid, hypochlorous acid, chloric acid, perchloric acid or ammonium persulfate.

Specifically, the method for preparing Li ₄ Mn _x R _y O ₁₂ composite oxide and manganese-based ion sieve adsorbent Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O in the present invention includes, taking R as titanium as an example, Follow the steps below:

(1) Mix and grind 4.2×10 ^-2 ~1.8mmol of titanium sulfate, 14.2~12.1mmol of manganese dioxide and 11.4mmol of lithium nitrate until uniform. Wherein, the molar ratio of titanium/manganese/lithium is (0.01～0.16):(1.24～1.09):1 (or use tin dioxide, zirconium dioxide, iron nitrate, Nickel nitrate, cobalt tetroxide, aluminum nitrate, etc. instead of titanium sulfate);

(2) Transfer the mixture obtained in step (1) to a temperature of 350-450° C. (for example, in a muffle furnace), and calcinate in dynamic air for 6-24 hours to obtain a precursor;

(3) The precursor obtained in the step (2) is soaked with a leaching agent, and then dried to obtain an ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O. It should be pointed out that the manganese salt used in the present invention is not limited to the above-mentioned manganese dioxide, and can also be manganese carbonate, manganese sulfate, manganese fluoride, manganese chloride or manganese iodide; the lithium salt used is not limited to the above-mentioned lithium nitrate , can also be lithium hydroxide, lithium nitrate, lithium carbonate, lithium sulfate, lithium phosphate, lithium chloride; the zirconium salt used is not limited to the above-mentioned zirconium dioxide, but can also be zirconium sulfate, zirconium chloride, zirconium nitrate; use The titanium salt is not limited to the above-mentioned titanium sulfate, but can also be titanium dioxide, titanium sulfate, n-butyl titanate; the iron salt used is not limited to the above-mentioned iron nitrate, and can also be iron hydroxide, iron sulfate, iron oxide, chloride Iron; the nickel salt used is not limited to the above-mentioned nickel nitrate, it can also be nickel hydroxide, nickel sulfate, nickel chloride, nickel oxide; the cobalt salt used is not limited to the above-mentioned cobalt dioxide, it can also be cobalt nitrate, cobalt sulfate , cobalt carbonate, cobalt hydroxide; the aluminum salt used is not limited to the above-mentioned aluminum nitrate, it can also be aluminum sulfate, aluminum hydroxide, aluminum oxide; the above-mentioned leaching agent is hydrochloric acid, sulfuric acid, Nitric acid, hypochlorous acid, chloric acid, perchloric acid or ammonium sulfite. The preferred technical solution of the present invention is: the molar ratio of tetravalent R, divalent manganese and monovalent lithium in the preferred step (1) is (0.07～0.16): (1.17～1.09): 1, and calcined in the preferred step (2) The temperature is 350～450℃, and the time is 12～24h.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1

Dissolve 11.4 mmol of lithium nitrate in 15 ml of deionized water, then add 14.2 mmol of manganese dioxide and 4.2×10 ^-2 mmol of titanium sulfate, stir in a water bath at 80°C until the water is completely removed; transfer the resulting mixture to a muffle furnace calcination at 350°C for 24 hours to obtain the precursor Li ₄ Mn _4.75 Ti _0.25 O ₁₂ , the XRD pattern of the product is shown in Figure 1, and the SEM pattern is shown in Figure 2; Under the conditions, pure phase Li ₄ Mn _4.75 Ti _0.25 O ₁₂ can be obtained, and the particle size of the product is relatively uniform. Take 0.8g of the precursor and place it in 200ml of 0.5mol/L hydrochloric acid solution, put it into a constant temperature water bath oscillator to oscillate at a frequency of 130rpm, control the temperature at 30°C, and react for 12h to extract Li ⁺ from the precursor; further filter, use Completely wash with ionic water, take the specific conductance of the washing liquid as the standard of less than 10 ^-5 Ω ^-1 m ^-1 , filter with suction, and dry in static air at 60°C for 3 hours to obtain the ion sieve adsorbent Mn _0.95 Ti _0.05 O of the present invention ₂ · 0.31 H ₂ O.

Example 2

Mix and grind 1.0mmol ferric hydroxide, 90.0mmol lithium nitrate and 99.0mmol manganese carbonate evenly, place them in a muffle furnace, and calcinate at 400°C for 24 hours with an air flow rate of 50mL/min to obtain Li ₄ Mn _4.5 Fe _0.5 O ₁₂ , the XRD pattern of the product is shown in Figure 3. Take 0.8g of the precursor and place it in 200ml of 0.5mol/L hydrochloric acid solution, put it into a constant temperature water bath oscillator to oscillate at a frequency of 130rpm, control the temperature at 30°C, and react for 12h to extract Li ⁺ from the precursor; further filter, use Complete washing with ionic water, with the specific conductance of the washing liquid less than 10 ^-5 Ω ^-1 m ^-1 as the standard, suction filtration, and drying in static air at 60°C for 3 hours, the ion sieve adsorbent Mn _0.9 Fe _0.1 O of the present invention can be obtained ₂ · 0.31 H ₂ O. The manganese dissolution loss in the pickling process was 0.7%.

Example 3

Dissolve 39.9mmol of lithium chloride in 20ml of deionized water, then add 1.0mmol of zirconium dioxide and 44.8mmol of manganese sulfate, stir in a water bath at 80°C until the water is completely evaporated to dryness; transfer the resulting mixture to a muffle furnace, Calcined at 450°C for 48 hours to obtain the precursor Li ₄ Mn ₄ ZrO ₁₂ . Take 0.8g of the precursor and place it in 200ml of 0.5mol/L ammonium persulfate solution, put it into a constant temperature water bath oscillator to oscillate at a frequency of 130rpm, control the temperature at 30°C, and react for 12h to extract Li ⁺ from the precursor; further filter, Completely wash with deionized water, take the specific conductance of the washing liquid to be less than 10 ^-5 Ω ^-1 m ^-1 as the standard, filter with suction, and dry in static air at 60°C for 3 hours to obtain the ion sieve adsorbent Mn _0.8 Zr of the present invention _0.2 O ₂ ·0.31 H ₂ O. The manganese dissolution loss in the pickling process is 0.5%.

Example 4

Dissolve 39.9mmol of lithium chloride in 20ml of deionized water, add 1.0mmol of tin dioxide and 44.8mmol of manganese sulfate, stir in a water bath at 80°C until the water is completely evaporated to dryness; transfer the resulting mixture to a muffle furnace, Calcined at 450°C for 48 hours to obtain the precursor Li ₄ Mn ₄ SnO ₁₂ . Take 0.8g of the precursor and place it in 200ml of 0.5mol/L ammonium persulfate solution, put it into a constant temperature water bath oscillator to oscillate at a frequency of 130rpm, control the temperature at 30°C, and react for 12h to extract Li ⁺ from the precursor; further filter, Wash completely with deionized water, take the specific conductance of the washing liquid as less than 10 ^-5 Ω ^-1 m ^-1 as the standard, filter with suction, and dry in static air at 60°C for 3 hours to obtain the ion sieve adsorbent Mn _0.8 Sn of the present invention _0.2 O ₂ ·0.31 H ₂ O. The manganese dissolution loss in the pickling process was 0.6%.

Example 5

Take 0.8g of the precursor of Example 1 Li ₄ Mn _4.75 Ti _0.25 O ₁₂ and add 200mL of 0.5mol/L ammonium persulfate solution, put it into a constant temperature water bath oscillator to vibrate at a frequency of 130rpm, control the temperature at 30°C, and react for 12h to leach out Li ⁺ in the precursor; further filtered, washed completely with deionized water, with the specific conductance of the washing solution less than 10 ^-5 Ω ^-1 m ^-1 as the standard, suction filtered, and dried in static air at 60°C for 3 hours, to obtain The ion sieve adsorbent of the present invention is Mn _0.95 Ti _0.05 O ₂ ·0.31H ₂ O. The manganese dissolution loss in the pickling process was 0.7%.

Example 6

Take 0.8g of Li ₄ Mn _4.75 Ti _0.25 O ₁₂ from Example 1 and add 200mL of 0.1mol/L HCl solution, put it into a constant temperature water bath oscillator to vibrate at a frequency of 130rpm, control the temperature at 30°C, and react for 12h to leach out the Li ⁺ ; further filtered, washed completely with deionized water, with the specific conductance of the washing liquid less than 10 ^-5 Ω ^-1 m ^-1 as the standard, suction filtered, and dried in static air at 120°C for 8 hours to obtain the ions of the present invention Sieve Mn _0.95 Ti _0.05 O ₂ ·0.31 H ₂ O. The XRD pattern of the ion sieve is shown in Figure 4, and the SEM image of the ion sieve is shown in Figure 5; comparing Figure 1 with Figure 4, it can be found that the structure has not changed significantly before and after pickling, and is still a spinel structure. Comparing Figure 2 with Figure 5, it can be seen that the morphology of the ion sieve does not change significantly after pickling.

Example 7

Dissolve 80.0 mmol of lithium nitrate in 20 ml of deionized water, and then add 98.0 mmol of manganese carbonate and 1.0 mmol of dicobalt trioxide. Stir in an 80°C water bath and evaporate to dryness. The obtained mixture was transferred to a muffle furnace, calcined at 450° C. for 24 hours, cooled and eluted in 1 mol/l ammonium persulfate solution to obtain an ion sieve Mn _0.98 Co _0.02 O ₂ ·0.31H ₂ O. The manganese dissolution loss rate in the pickling process is only 0.7%. The XRD pattern of this product is shown in 6.

Example 8

Dissolve 40mmol of lithium hydroxide in 5ml of deionized water, add 49mmol of manganese chloride and 1mmol of aluminum nitrate, stir in a water bath at 80°C, and evaporate to dryness. Grind evenly in a mortar; transfer the obtained mixture to a muffle furnace, calcinate at 400°C for 24 hours, cool and elute in 1mol/l hydrochloric acid solution to obtain ion sieve Mn _0.98 Al _0.02 O ₂ ·0.31H ₂ O. The manganese dissolution loss rate in the pickling process is only 0.9%. The SEM image of the product is shown in Figure 7.

Example 9

Dissolve 80.0 mmol of lithium nitrate in 20 ml of deionized water, and then add 98.0 mmol of manganese carbonate and 2.0 mmol of nickel sulfate. Stir in an 80°C water bath and evaporate to dryness. The resulting mixture was transferred to a muffle furnace, calcined at 450°C for 24 hours, cooled and eluted in 1 mol/l ammonium persulfate solution to obtain an ion sieve Mn _0.98 Ni _0.02 O ₂ ·0.31H ₂ O. The manganese dissolution loss rate in the pickling process is only 1%. The XRD pattern of the product is shown in Figure 8.

Adsorption effect test 1

The sample ion sieve adsorbent prepared by weighing 100mg examples 1, 2, 3, 7, 8 and 9 (respectively doped with titanium, iron, zirconium, cobalt, aluminum and nickel ions) is put into a conical flask with a sieve, Add 10mL of 10mmol/L mixed ion solution (Li ⁺ , Na ⁺ , K ⁺ , Ca ²⁺ , and Mg ²⁺ , pH=10.1), place on an intelligent multifunctional large-scale shaker and vibrate at a frequency of 130rpm, and control the temperature at 30 °C, reacted for 120 h, took the supernatant and monitored the concentration of each ion in it with IC, the results are shown in Table 1.

Adsorption selectivity of table 1 ion sieve

It can be seen from Table 1 that the ion sieve has higher selectivity for the adsorption of Li ions than common coexisting ions, and has important practical value for lithium extraction from salt lakes and seawater.

Adsorption effect test 2

Weigh 100 mg of the sample ion sieves prepared in Examples 1, 3 and 6, respectively, and put them into a conical flask with a sieve, and add 100 mL of Chaerhan brine. Put it on an intelligent multifunctional large-scale shaker and oscillate at a frequency of 130rpm, control the temperature at 30°C, and react for 48 hours. Take the upper clear layer and use IC to monitor the concentration of lithium ions in it. The amount of lithium ions adsorbed by the ion sieve is 3.2mmol/g. , 5.5 mmol/g and 4.1 mmol/g.

Comparative test:

Weigh 100 mg sample ion sieve prepared by Example 4 and MnO ₂ ·0.4H ₂ O not doped with other ions, respectively, and put them into a conical flask with a sieve, and add 100 mL of Chaerhan brine. Put it on an intelligent multifunctional large-scale shaker and oscillate at a frequency of 130rpm, control the temperature at 30°C, and react for 48 hours. Take the upper clear layer and use IC to monitor the concentration of lithium ions in it. The amount of lithium ions adsorbed by the ion sieve is 3.8mmol/g. and 3.5mmol/g. The manganese dissolution rate is 0.4% and 2%, respectively. It can be seen that by selecting appropriate doping ions and doping amounts, not only the adsorption capacity of ion sieves for lithium ions can be effectively increased, but also the manganese dissolution loss rate can be greatly reduced, and products with better stability can be prepared.

Those skilled in the art understand that the improvement of stability is mainly reflected in the reduction of manganese dissolution rate. The manganese dissolution loss rate is reduced, and the ion sieve can be used more times, that is to say, the stability is improved.

It can be seen from the above examples that the synthesis method, experimental conditions and product ratio of the present invention are easy to control, and the conditions for obtaining ideal products are wide; the ion sieve adsorbent Mn _x/5 R _y/5 O ₂ synthesized by the present invention is ·0.31H ₂ O (where R=Sn, Zr, Ti, Fe, Ni, Co, or Al) can be used to extract lithium from lithium-containing solutions such as salt lake brine and seawater, and has the advantages of large adsorption capacity and good repeatability.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (10)

1. A method for regulating the stability of lithium-ion sieves by cation doping, comprising preparing lithium-ion sieve precursor composite oxides Li ₄ Mn _x R _y O ₁₂ , wherein the dopant ions R are Sn, Zr, Ti, , Fe , Ni, Co, or Al, and 2.5≤x≤4.996, 0.004≤y≤2.5, x+y is 5.0, the preparation of the composite oxide Li ₄ Mn _x R _y O ₁₂ includes: (1) Mix divalent manganese salt, lithium salt and R-containing compound so that the molar ratio of R/manganese/lithium is (0.625～0.001):(0.625～1.249):1.00, and (R+manganese)/lithium mole The ratio is 1.1~1.5; (2) Calcining the mixture obtained in step (1) at 350-650° C. under dynamic air conditions for 6-120 hours to obtain the composite oxide. 2. The method according to claim 1, characterized in that, in step (1), the divalent manganese salt is manganese carbonate, manganese sulfate, manganese fluoride, manganese chloride, manganese iodide or a combination thereof. 3. The method according to claim 1, wherein in step (1), the lithium salt is lithium nitrate, lithium carbonate, lithium sulfate, lithium phosphate, lithium hydroxide, lithium chloride or a combination thereof. 4. The method according to claim 1, characterized in that, in step (1), the compound containing R is tin dioxide, zirconium dioxide, zirconium sulfate, zirconium chloride, zirconium nitrate, titanium dioxide, titanium sulfate , n-butyl titanate, ferric nitrate, ferric hydroxide, ferric sulfate, ferric oxide, ferric chloride, nickel hydroxide, nickel sulfate, nickel nitrate, nickel chloride, nickel oxide, cobalt nitrate, cobalt sulfate, cobalt carbonate, Cobalt hydroxide, cobalt tetroxide, aluminum nitrate, aluminum sulfate, aluminum hydroxide, aluminum oxide, or combinations thereof. 5. The method according to claim 1, characterized in that, in step (1), the molar ratio of R/manganese/lithium is (0.01-0.16): (1.24-1.09): 1, and the mixing is carried out in water , and remove moisture before carrying out the calcination of step (2). 6. The method according to claim 1, characterized in that the molar ratio of R/manganese/lithium in step (1) is (0.07～0.16): (1.17～1.09): 1, and the calcined The temperature is 350-450°C, and the time is 12-72 hours. 7. A method for regulating the stability of a lithium ion sieve by cation doping, comprising: the composite oxide Li _{Mn x} R _y O ₁₂ obtained in any one of claims 1-6 Washing, drying, and then leaching The cation-doped lithium ion sieve Mn _x/ 5R _y/5 O ₂ ·0.31H ₂ O is obtained. 8. The method according to claim 7, wherein the leaching agent is 0.1-1 mol/L hydrochloric acid, sulfuric acid, nitric acid, hypochlorous acid, chloric acid, perchloric acid or ammonium persulfate. 9. A composite oxide Li ₄ Mn _x R _y O ₁₂ , wherein the dopant ion R is Sn, Zr, Ti, Fe, Ni, Co, or Al, and 2.5≤x≤4.996, 0.004≤y≤2.5 , x+y is 5.0. 10. A cation-doped lithium ion sieve Mn _x/5 R _y/5 O ₂ ·0.31H ₂ O, wherein the dopant ion R is Sn, Zr, Ti, Fe, Ni, Co, or Al, and 2.5 ≤x≤4.996, 0.004≤y≤2.5, x+y is 5.0.