Modified layered manganese dioxide positive electrode active material, preparation thereof and application of modified layered manganese dioxide positive electrode active material in aqueous zinc ion battery

Abstract

The invention belongs to the field of zinc ion batteries, and particularly relates to a modified layered manganese dioxide positive electrode active material, preparation thereof and application of the modified layered manganese dioxide positive electrode active material in an aqueous zinc ion battery, and the preparation method of the active material comprises the following steps: carrying out solvothermal modification treatment on a mixed solution A containing a manganese source, an auxiliary agent (# imgabs0 #) in a formula 1 and an alcohol-water solvent, the first-stage modified MnO2 subjected to interlayer grafting modification is prepared; and dispersing the first-stage modified MnO2 in a solution B dissolved with an elastic precursor compound and an oxidizing agent for second-stage modification to prepare the modified layered manganese dioxide positive electrode active material. The elastic precursor compound comprises at least one of a formula A (# imgabs 1 #), a formula B (# imgabs 2 #), a formula C (# imgabs 3 #) and a formula D (# imgabs 4 #). The material prepared by the method disclosed by the invention is beneficial to inducing deposition of zinc, improving wetting of an electrolyte and improving the capacity exerting rate of the material in a zinc battery and the performance of the material under high rate.

Description

Technical Field

[0001] The invention belongs to the field of aqueous zinc ion batteries, and in particular relates to the field of manganese dioxide positive electrode materials for zinc ion batteries. Background Art

[0002] Zinc-ion batteries (ZIBs) have become an important candidate for the next generation of energy storage systems due to their high safety, low cost, and environmental friendliness. 2 ) has attracted much attention as a cathode material for zinc-ion batteries due to its high theoretical capacity and abundant resources. 2 In practical applications, it faces problems such as slow zinc ion diffusion kinetics, poor structural stability and high interfacial reaction impedance, which seriously limit its electrochemical performance.

[0003] In view of the problems existing in manganese dioxide positive electrode active materials, the prior art has proposed some modification ideas such as element doping, surface modification and nanostructure design. For example, the patent document with publication number CN119706948A discloses a cerium-copper co-doped δ-MnO 2 Preparation method of microsphere aqueous zinc ion battery positive electrode material. Patent document with publication number CN119390126A discloses a method of preparing a positive electrode material of a microsphere aqueous zinc ion battery. 3 [Co(CN) 6 ] 2 A method for preparing a cobalt-doped manganese dioxide material for a hard template. Patent document No. CN114212826A discloses a Mo metal-doped MnO 2 Electrode material and preparation method thereof. Patent document with publication number CN114899389A discloses a Ga-modified MnO 2 Preparation method of nanorods. Patent document with publication number CN117747820A discloses an Al-doped α-MnO 2 The patent document with publication number CN116199264A discloses a non-metallic B-doped β-phase MnO 2 Electrode materials. For example, the patent document with publication number CN118888721A discloses a C-coated δ-MnO containing O vacancies. 2 Positive electrode material and its preparation method and application. Patent document with publication number CN117623393A discloses a positive electrode material MnO 2 @CNT and its preparation method.

[0004] In summary, although the prior art discloses many doping or coating modification schemes, the existing methods can often only improve one aspect of the performance, and it is difficult to simultaneously solve the problems of low conductivity, large Mn dissolution loss, unsatisfactory material capacity utilization, long cycle life, and rate performance. Summary of the invention

[0005] In view of the problems of low conductivity, Mn dissolution caused by Jahn-Teller effect and insufficient cycle life of existing manganese dioxide positive electrode active materials, the first object of the present invention is to provide a method for preparing a modified layered manganese dioxide positive electrode active material, aiming to prepare a positive electrode active material with dual interlayer and surface modifications and excellent electrochemical properties.

[0006] The second object of the present invention is to provide a modified layered manganese dioxide positive electrode active material obtained by the preparation method.

[0007] The third object of the present invention is to provide an application of the modified layered manganese dioxide positive electrode active material in the preparation of an aqueous zinc ion battery.

[0008] The fourth object of the present invention is to provide an aqueous zinc ion battery comprising the modified layered manganese dioxide positive electrode active material.

[0009] A method for preparing a modified layered manganese dioxide positive electrode active material, comprising subjecting a mixed solution A comprising a manganese source, an auxiliary agent of formula 1 and an alcohol-water solvent to a solvent thermal modification treatment to obtain a first-stage modified MnO 2 ; Then a modified MnO 2 Dispersing in a solution B containing an elastic precursor compound and an oxidant for second stage modification to obtain the modified layered manganese dioxide positive electrode active material;

[0010]

[0011] Formula 1

[0012] In formula 1, R 1 , R 2 Alone for H, C 1 ~C 4 Alkyl or C 1 ~C 4 or, R 1 , R 2 Ring closure to form an aromatic ring;

[0013] The elastic precursor compound comprises at least one of Formula A, Formula B, Formula C and Formula D;

[0014] Formula A;

[0015] Formula B;

[0016] Formula C;

[0017] Formula D;

[0018] R 3 C 1 ~C 4 The alkyl group;

[0019] R 4 H or C 1 ~C 4 of alkyl.

[0020] The present invention innovatively performs solvent thermal treatment on the manganese source and the auxiliary agent of formula 1 in an alcohol-water solvent, so that layered manganese dioxide can be synthesized, and manganese dioxide and the reaction-modified material of formula 1 are selectively modified in situ between the layers of manganese dioxide, so as to construct a better zinc deposition space and optimize the uniformity of zinc deposition. In addition, the second stage modification is further performed using an elastic precursor compound and an oxidant, so as to construct an elastic modified interface of a pro-electrolyte on the surface of manganese dioxide. The present invention has shown that the combination of the interlayer modification assisted by the solvent thermal participation of the alcohol-water solvent of formula 1 and the surface modification participated by the elastic precursor compound can achieve synergy, help induce the deposition of zinc, improve the wetting of the electrolyte, and help improve the capacity utilization rate of the material in the zinc battery and the performance at high rates.

[0021] In the present invention, the manganese source includes MnSO 4 、Mn(CH 3 COO 2 、KMnO 4 At least one of; preferably a mass ratio of 0.2 to 1.2: 1, and further can be 0.6 to 0.8: 1 of potassium permanganate and manganese sulfate.

[0022] In the present invention, the manganese source is solvent-thermally modified in a system containing an auxiliary agent of formula 1 and an alcohol-water solvent, so that layered manganese dioxide can be successfully prepared. Not only that, it is also beneficial to graft zinc-philic and hydrophobic modified materials between the layers of the layered manganese dioxide, which is beneficial to the combined synergy with the subsequent second-stage modification to improve the capacity and high-rate performance of the material.

[0023] In Formula 1 of the present invention, R 1 , R 2 They may be independent substituents, or they may be fused together to form an aromatic ring, and the aromatic ring may be, for example, a benzene ring.

[0024] Further, the auxiliary agent of formula 1 includes at least one of formula 1A and formula 1B;

[0025] Formula 1A

[0026] Formula 1B.

[0027] The present invention shows that the use of Formula 1B as an auxiliary agent of Formula 1 can further improve process synergy, help to further improve the interlayer modification effect of manganese dioxide, and help to further improve the performance of the prepared material.

[0028] The weight ratio of the additive of formula 1 to the manganese source is 0.5-1.5:1; further, it can be 0.6-1:1; further, it can be 0.7-0.8:1.

[0029] In the present invention, the use of the alcohol-water solvent is helpful for forming layered manganese dioxide. Moreover, it is also beneficial for combining with the auxiliary agent of formula 1 to in-situ induce zinc-philic and hydrophobic modified structures between the layers of the layered manganese dioxide.

[0030] In the present invention, the alcohol in the alcohol-water solvent is C 1 ~C 4 The monoalcohol, diol or triol can be selected from the group consisting of methanol, ethanol, isopropanol, etc.

[0031] In the alcohol-water solvent, the volume ratio of water to alcohol is 2-6:1; further, it can be 3-5:1.

[0032] In the mixed solution A, the weight ratio of the manganese source to the alcohol-water solvent may be 1:1-20; considering the processing scale and cost, it may be further 1:3-10.

[0033] In the present invention, the temperature of the solvent thermal modification treatment is 100-200° C., further 120-180° C., and further 120-150° C. In the present invention, preferably at the solvent thermal temperature, the modification effect of the additive of formula 1 can be further enhanced, which helps to further improve the high current long cycle effect of the prepared material.

[0034] In the present invention, the solvent thermal modification treatment time is 8 to 20 hours, and can further be 10 to 12 hours.

[0035] In the present invention, a modified MnO 2 Dispersed in solution B containing an elastic precursor compound, an oxidant, based on the elastic precursor compound, the oxidant and a first modified MnO 2 The combination of surface characteristics is conducive to the construction of a lyophilic modified interface on its surface, which is conducive to combining with the first stage modification (solvent thermal modification) to synergistically enhance the performance of the material.

[0036] In the present invention, the solvent in solution B is at least one of water and an organic solvent; wherein the organic solvent includes C1 ~C 4 At least one of alcohol, acetonitrile and acetone.

[0037] Preferably, the solvent in solution B comprises a mixed solvent of water-organic solvent in a mass ratio of 5 to 15:1. The present invention shows that the use of the preferred solvent to assist the modification of the elastic precursor compound is helpful to further combine with the additive of formula 1 to strengthen the interlayer and surface modification effect of manganese dioxide, and to further improve the stability of the prepared material, especially to improve its long cycle stability under high current.

[0038] In the present invention, the elastic precursor compound is preferably Formula B. Studies have shown that Formula B, compared with other components, can be further combined with the process of the present invention to further improve the long cycle stability of the assembled battery under high current.

[0039] In the present invention, in solution B, the elastic precursor compound and a modified MnO 2 The weight ratio is 0.2~3:1; more preferably 0.5~0.8:1.

[0040] In the present invention, the oxidant is a persulfate, for example, at least one of sodium persulfate and ammonium persulfate.

[0041] In the present invention, the oxidant is a modified MnO 2 The amount may be 0.002 to 0.01 times by weight, and may further be 0.003 to 0.005 times by weight.

[0042] In the present invention, in solvent B, a modified MnO 2 The mass concentration can be 5-30%; further can be 10-20%.

[0043] In the present invention, the temperature of the second modification process is 25-50° C. and the time is 2-10 hours.

[0044] In the present invention, after the second stage modification, a third stage modification treatment with the participation of alkali solution can be selectively carried out as required.

[0045] The alkali solution is a sodium hydroxide solution with a concentration of 0.5-2M.

[0046] The weight ratio of the alkaline solute in the alkali solution to the product of the second stage modification can be 0.1 to 1 times, and further can be 0.4 to 0.6 times.

[0047] The invention also provides a modified layered manganese dioxide positive electrode active material prepared by the preparation method.

[0048] The preparation method of the present invention can give the prepared material special physical and chemical characteristics, for example, a layered manganese dioxide can be obtained, and a conversion modification layer of formula 1 and a surface layer converted by an elastic precursor compound can be constructed between the layers. In addition, the material with special physical and chemical characteristics prepared by the preparation method of the present invention can improve zinc deposition, improve lyophilicity and ion and electron conduction pathways, and help significantly improve its performance.

[0049] The present invention also provides an application of the modified layered manganese dioxide positive electrode active material prepared by the preparation method, which is used as a positive electrode active material to prepare an aqueous zinc ion battery.

[0050] The present invention also provides an aqueous zinc ion battery, wherein the positive electrode of the aqueous zinc ion battery comprises the modified layered manganese dioxide positive electrode active material obtained by the preparation method.

[0051] The aqueous zinc ion battery of the present invention, in addition to comprising the modified layered manganese dioxide positive electrode active material of the present invention, may have other components and structures that are well known.

[0052] Beneficial Effects

[0053] The present invention innovatively synthesizes layered manganese dioxide with the assistance of an auxiliary agent of formula 1 and an alcohol-water solvent, and constructs a zinc-philic hydrophobic modified structure in situ of the layered manganese dioxide, and further performs a second stage modification with the participation of an elastic precursor compound and an oxidant, so that a lyophilic structure can be constructed on the surface of the manganese dioxide. The present invention studies show that the material with special physical and chemical characteristics prepared by the preparation method is helpful in inducing zinc deposition, improving the wetting of the electrolyte, and helping to improve the capacity utilization rate of the material in a zinc battery and the performance at high rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a cycle performance diagram of the zinc ion battery obtained in Example 1 at 25°C and a current density of 0.2 A / g;

[0055] Figure 2 This is a cycle performance diagram of the zinc ion battery obtained in Example 1 at 25°C and 2 A / g current density. DETAILED DESCRIPTION

[0056] In the present invention, as an illustrative solution, the elastic precursor material may be a component of formula B and formula C, wherein, as a specific optional solution, the formula B may be specifically exemplified by formula B1, which is R 3The compound of formula B is a methyl compound. In the present invention, after the second stage modification treatment is performed using the component, an alkali solution treatment may be optionally continued to obtain the final product. The alkali solution of the alkali solution treatment may be a sodium hydroxide solution with a concentration of 0.5 to 2M. The weight ratio of the alkali in the alkali solution to the formula B1 may be 0.4 to 0.8:1. The alkali solution treatment time may be 1 to 5 hours.

[0057] In the present invention, the formula C is represented by formula C1, which is specifically R 4 The formula is C of H.

[0058] Example 1

[0059] Step 1: Premix:

[0060] The auxiliary agent of formula 1 (formula 1B in this case), a manganese source (the manganese source is potassium permanganate and manganese sulfate in a mass ratio of 0.7:1) and solvent A (a mixed solution of water and ethanol in a volume ratio of 3:1) in a mass ratio of 0.8:1:4 are fully mixed.

[0061] Step 2: First modification

[0062] The mixture obtained in step 1 was transferred to a polytetrafluoroethylene solvent thermal reactor (pressure reactor), and the solvent thermal reaction was carried out at 130°C for 12 hours, followed by filtration and washing to obtain a modified manganese dioxide material (labeled as Z-MnO 2 ).

[0063] Step 3: Second modification

[0064] Solvent B (a mixed solution of water and methanol in a mass ratio of 12:1) with a mass ratio of 9:0.6:1:0.005, an elastic precursor compound (in this case, Formula B1, which is R 3 Formula B), Z-MnO 2 , potassium persulfate was modified by stirring at 30°C for 5 hours; then 1M NaOH (the solvent is methanol; wherein the sodium hydroxide is 0.5-0.6 times the weight of formula B1) was modified by stirring at 30°C for 3 hours, and then filtered and cleaned to obtain HZ-MnO 2 .

[0065] Example 2

[0066] Compared with Example 1, the only difference is that the auxiliary agent of Formula 1 in Step 1 is changed to Formula 1A, and the other operations and parameters are the same as those in Example 1.

[0067] Example 3

[0068] Compared with Example 1, the only difference is that in step 1, the weight ratio of the auxiliary agent of formula 1 (formula 1B in this case), the manganese source (the manganese source is potassium permanganate and manganese sulfate in a mass ratio of 0.6:1) and the solvent A (a mixed solution of water and ethanol in a volume ratio of 5:1) is 0.7:1:8; the temperature in step 2 is 160°C and the time is 10 h.

[0069] Other operations and parameters are the same as in Example 1.

[0070] Example 4

[0071] Compared with Example 1, the only difference is that the conditions of step 3 are changed, and the experimental groups are:

[0072] Group A: Solvent B is water;

[0073] Group B: solvent B is methanol;

[0074] Other operations and parameters are the same as in Example 1.

[0075] Example 5

[0076] Compared with Example 1, the only difference is that the conditions of step 3 are changed, and the experimental groups are:

[0077] Group A: The elastic precursor compound is of formula C1; after modification in step 3, no subsequent sodium hydroxide treatment is required;

[0078] Group B: Solvent B is a mixed solution of water and ethanol with a mass ratio of 10:1, and solvent B, elastic precursor compound, Z-MnO 2 , the weight ratio of ammonium persulfate is 8:0.7:1.5:0.004, the reaction temperature is 45°C, and the reaction time is 3 hours.

[0079] Other operations and parameters are the same as in Example 1.

[0080] Comparative Example 1

[0081] Compared with Example 1, the only difference is that in step 1, no auxiliary agent of formula 1 is added, and other operations and parameters are the same as in Example 1.

[0082] Comparative Example 2

[0083] Compared with Example 1, the only difference is that in step 1, the same weight of The auxiliary agent of formula 1 is replaced, and other operations and parameters are the same as those in Example 1.

[0084] Comparative Example 3

[0085] Compared with Example 1, the only difference is that in step 1, the same weight of The auxiliary agent of formula 1 is replaced, and other operations and parameters are the same as those in Example 1.

[0086] Comparative Example 4

[0087] Compared with Example 1, the only difference is that in step 1, solvent A is water, the amount of solvent A and other operations and parameters are the same as in Example 1.

[0088] Comparative Example 5

[0089] Compared with Example 1, the only difference is that in step 1, solvent A is methanol, the amount of solvent A and other operations and parameters are the same as in Example 1.

[0090] Comparative Example 6

[0091] Compared with Example 1, the only difference is that in step 3, no elastic precursor compound is added, and other operations and parameters are the same as in Example 1.

[0092] Comparative Example 7

[0093] Compared with Example 1, the only difference is that the elastic precursor compound in solution B is added to the solvent A in step 1, and the auxiliary agent of formula 1 in solvent A is added to solution B. Other operations and parameters are the same as in Example 1.

[0094] Full cell assembly and performance determination

[0095] The manganese dioxide active material, conductive carbon black, and polyvinylidene fluoride finally obtained in each case were mixed evenly in a mass ratio of 7:2:1, and an appropriate amount of NMP was added as a dispersant to make a uniform slurry. The slurry was then coated on the surface of the stainless steel mesh current collector and transferred to 60°C for vacuum drying for 12 hours to obtain the positive electrode sheet. It was then cut into circular electrodes with a diameter of about 10 mm using a cutting machine. The surface load of the obtained positive electrode sheet was about 1.5 mg / cm 2 . The positive battery shell, positive electrode sheet, glass fiber separator, 0.1 mm zinc foil negative electrode, nickel foam, and negative battery shell were assembled into a CR2025 button battery. 2M ZnSO 4 +0.1MMnSO 4 Aqueous electrolyte, and finally sealed with a battery packaging machine. At 25°C, the assembled aqueous zinc ion battery was charged and discharged using a low current of 0.2A / g and a high current of 2A / g to explore the electrochemical properties of the material. The voltage range of the test was 0.8V-1.8V, and the test instrument was a Blue Electric electrochemical measurement system. The results are shown in Table 1:

[0096]

[0097] It can be seen from Example 1 and Comparative Examples 1 to 7 that by pre-synthesizing layered manganese dioxide with the aid of the auxiliary agent of formula 1 of the structure described in the present invention and an alcohol-water solvent, and then performing a second-stage modification with the participation of an elastic precursor compound, a lyophilic structure can be constructed on the surface of manganese dioxide, which helps to improve the capacity utilization rate of the material in zinc batteries and the performance at high rates.

[0098] In addition, it can be seen from Examples 1 and 2 that by using Formula 1B as an auxiliary agent of Formula 1, better process synergy can be obtained. It can be seen from Examples 1 and 4 that by innovatively carrying out the second stage modification treatment assisted by the elastic precursor compound in an alcohol-water mixed solvent, better process synergy can be obtained. It can be seen from Examples 1 and 5 that by using Formula B described in the present invention as an elastic precursor compound, better process modification effect can be obtained.

Claims

1. A method for preparing a modified layered manganese dioxide positive electrode active material, characterized in that: A mixed solution A containing a manganese source, an additive of formula 1 and an alcohol-water solvent is subjected to solvothermal modification to obtain a first-stage modified MnO2 with interlayer grafting modification; and the first-stage modified MnO2 is dispersed in a solution B containing an elastic precursor compound and an oxidant for a second stage modification to obtain the modified layered manganese dioxide positive electrode active material; ； Formula 1 In Formula 1, R1 and R2 are independently H, C1-C4 alkyl or C1-C4 alkoxy; or, R1 and R2 are cyclized to form an aromatic ring; The elastic precursor compound comprises at least one of Formula A, Formula B, Formula C and Formula D; Formula A; Formula B; Formula C; Formula D; R3 is a C1~C4 alkyl group; R4 is H or a C1~C4 alkyl group.

2. The method for preparing the modified layered manganese dioxide positive electrode active material according to claim 1, characterized in that: The manganese source includes at least one of MnSO4, Mn(CH3COO)2, and KMnO4; The auxiliary agent of formula 1 includes at least one of formula 1A and formula 1B; Formula 1A; Formula 1B; The weight ratio of the additive of formula 1 to the manganese source is 0.5-1.5:

1.

3. The method for preparing the modified layered manganese dioxide positive electrode active material according to claim 1, characterized in that: The alcohol in the alcohol-water solvent is a C1-C4 monoalcohol, diol or triol; In the alcohol-water solvent, the volume ratio of water to alcohol is 2-6:1; In the mixed solution A, the weight ratio of the manganese source to the alcohol-water solvent is 1:1-20.

4. The method for preparing the modified layered manganese dioxide positive electrode active material according to any one of claims 1 to 3, characterized in that: The temperature of the solvent thermal modification treatment is 100~200℃, and the time is 8~20h.

5. The method for preparing the modified layered manganese dioxide positive electrode active material according to claim 1, characterized in that: The solvent in solution B is at least one of water and an organic solvent; wherein the organic solvent includes at least one of C1-C4 alcohol, acetonitrile and acetone.

6. The method for preparing the modified layered manganese dioxide positive electrode active material according to claim 5, characterized in that: In solution B, the solvent comprises a mixed solvent of water and an organic solvent in a mass ratio of 5 to 15:

1.

7. The method for preparing the modified layered manganese dioxide positive electrode active material according to claim 1, 5 or 6, characterized in that: The oxidant is persulfate; The oxidant is 0.002-0.01 times the weight of the first-stage modified MnO2; The weight ratio of the elastic precursor compound to the first-stage modified MnO2 is 0.2~3:1; In solution B, the mass concentration of the first-stage modified MnO2 is 5-30%; The temperature of the second modification process is 25~50℃ and the time is 2~10h.

8. A modified layered manganese dioxide positive electrode active material obtained by the preparation method according to any one of claims 1 to 7.

9. An application of a modified layered manganese dioxide positive electrode active material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: It is used as a positive electrode active material to prepare aqueous zinc ion batteries.

10. An aqueous zinc ion battery, characterized in that: The positive electrode of the aqueous zinc ion battery comprises a modified layered manganese dioxide positive electrode active material obtained by the preparation method described in any one of claims 1 to 7.

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