WO2022120592A1 - 一种基于多羧酸钾盐石墨复合负极材料的制备及钾离子电池应用 - Google Patents

一种基于多羧酸钾盐石墨复合负极材料的制备及钾离子电池应用 Download PDF

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WO2022120592A1
WO2022120592A1 PCT/CN2020/134647 CN2020134647W WO2022120592A1 WO 2022120592 A1 WO2022120592 A1 WO 2022120592A1 CN 2020134647 W CN2020134647 W CN 2020134647W WO 2022120592 A1 WO2022120592 A1 WO 2022120592A1
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potassium
polycarboxylate
graphite
negative electrode
electrode material
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PCT/CN2020/134647
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English (en)
French (fr)
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唐永炳
潘庆广
仝兆鹏
苏元强
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深圳先进技术研究院
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • the invention belongs to the technical field of batteries, and in particular relates to the preparation of a graphite composite negative electrode material based on potassium polycarboxylate and the application of potassium ion batteries.
  • potassium ions such as intercalated graphite or carbon materials, transformation-type transition metal chalcogenides and alloy-type metal materials, etc.
  • these materials store potassium
  • researchers have also begun to explore the use of organic materials as potassium ion storage electrode materials.
  • potassium phthalate can reversibly store two potassium ions and reduce the generation of potassium dendrites, ensuring the safety of batteries.
  • Triazine-based covalent organic frameworks can also be used for potassium ion storage, but their cycle stability and cycle life are poor. (ACS Nano, 2019, 13, 14252-14261).
  • Existing negative electrode materials for potassium ion batteries include intercalated graphite or carbon materials, alloyed metal and transition metal oxides and sulfides, and some organic compounds. Among them, the diffusion rate of potassium ions in carbon materials is slow, and the structure of carbon materials is easy to expand and pulverize, resulting in low coulombic efficiency, poor battery stability and rate performance; metal oxides and sulfides, due to the dissolution of intermediates and poor electrical conductivity, resulting in poor cycle stability and low capacity retention; for conventional metal tin, antimony, bismuth and other negative electrodes, due to the severe volume expansion during the cycle process, it is easy to cause electrode pulverization, which leads to cycle However, the reported organic materials have problems such as few active sites, low theoretical capacity and poor stability.
  • the object of the present invention is to aim at the deficiencies of the prior art, the present invention provides a kind of based on polycarboxylate potassium salt/graphite (with 1,2,4,5-potassium pyromellitic acid/reduced graphene oxide, K 4 PM/RGO as an example) preparation method of anode material and its application in novel secondary potassium ion battery.
  • polycarboxylate potassium salt/graphite with 1,2,4,5-potassium pyromellitic acid/reduced graphene oxide, K 4 PM/RGO as an example
  • a graphite composite negative electrode material based on potassium polycarboxylate the potassium polycarboxylate is dispersed on the surface of the graphite material, the side length of the potassium polycarboxylate nanosheet is 1-5 microns, and the content of graphite is 50 mg/L.
  • the general formula of the polycarboxylic acid structure is as follows (here it is a tetracarboxylic acid structure), the carboxylic acid structure can be three, four, five or six or n carboxylic acids, wherein the R group is a benzene ring , pyridine ring, pyrazine ring, pyrimidine ring, pyran ring, pyrrole ring, thiophene, furan.
  • the R group is a benzene ring.
  • a preparation method based on polycarboxylate potassium salt graphite composite negative electrode material comprising the following steps:
  • Step 101 Dissolve polycarboxylic acid and potassium source (salt or alkali) with a molar ratio of (4-0.125) in a solvent, respectively, and magnetically stir for 1-2 hours; label A solution and B solution respectively; wherein B solution is added Graphite materials, evenly mixed;
  • Step 102 Mix the above stirred A solution and B solution together to obtain a mixed solution C, wherein the addition sequence is that A is added to the B solution, stirred for 1-2 hours, and the obtained mixed solution C is poured into the polytetrafluoroethylene Ethylene lining, and put it into the reaction kettle, the reaction kettle is transferred to the oven for reaction, the temperature is 80-200 degrees Celsius, the reaction time is 6-24 hours, and it is lowered to room temperature after the reaction is completed;
  • Step 103 Centrifuge the above-reacted mixed solution C with a centrifuge at a rotational speed of 6000-10000 rpm for 8-12 minutes, then wash with ethanol and repeat the centrifugation for 3-5 times, put it into an oven for vacuum drying, and dry at a temperature of 60 °C. -80 degrees Celsius, the time is 12-48 hours, and finally the polycarboxylate potassium salt/graphite composite negative electrode material is obtained.
  • the potassium source (salt or alkali) in the step 101 is potassium nitrate, potassium chloride, potassium sulfate or potassium hydroxide.
  • the potassium source is potassium hydroxide.
  • the solvent in the step 101 is an organic solvent of ethanol, ethylene glycol, glycerol, N-N dimethylformamide, dimethyl sulfoxide, and acetone.
  • the solvent is a mixed solution of ethanol and ethylene glycol, and the volume ratio is 1:1.
  • the graphite material in the step 101 is graphite, expanded graphite, graphene, multi-layer graphene or graphene oxide.
  • the graphite material is graphene oxide.
  • the molar ratio of the polycarboxylic acid and potassium hydroxide in the step 101 is 1/8, the concentrations are respectively 10 and 80 mmol/L, and the content of the added graphite material is 50 mg/L.
  • the volume of the inner lining of the reactor is 250ml; the temperature of the reactor is 180 degrees Celsius, and the reaction time is 12 hours.
  • the centrifugal speed is 9000 rpm
  • the time is 10 minutes
  • the drying temperature is 70 degrees Celsius
  • the time is 24 hours.
  • An application based on a polycarboxylate potassium salt graphite composite negative electrode material is applied to lithium, sodium, potassium, and calcium ion batteries, and is used as a negative electrode material for lithium, sodium, potassium, and calcium ion batteries.
  • a potassium ion battery based on a polycarboxylate potassium salt graphite composite negative electrode material comprising a metal potassium sheet, a potassium ion half-cell negative electrode sheet, a diaphragm, an electrolyte and an outer shell, and the negative electrode sheet consists of an active material, a conductive agent, a viscose After the binder is mixed, an organic solvent is added, and it is ground into a slurry and then coated on a current collector to obtain; the active material in the negative electrode sheet is a polycarboxylate potassium salt/graphite composite material.
  • a preparation method of a potassium ion battery based on a polycarboxylate potassium salt graphite composite negative electrode material comprising the following steps: mixing the polycarboxylate potassium salt/graphite composite material, a conductive agent, and a binder in a mass ratio of 6:3:1 After mixing in proportions, nitrogen methyl pyrrolidone is added, and the slurry is ground and coated on copper foil.
  • the electrolyte includes one or more of inorganic potassium salts and organic potassium salts, which can be decomposed into K + and anions, and the diaphragm material is glass fiber.
  • the electrolyte is one of KPF 6 , K 2 SO 4 , KBH 4 , KBF 4 , KClO 4 , potassium bis-trifluoromethanesulfonimide (KTFSI) or potassium bisfluorosulfonimide (KFSI).
  • KPF 6 KPF 6 , K 2 SO 4 , KBH 4 , KBF 4 , KClO 4 , potassium bis-trifluoromethanesulfonimide (KTFSI) or potassium bisfluorosulfonimide (KFSI).
  • KTFSI potassium bis-trifluoromethanesulfonimide
  • KFSI potassium bisfluorosulfonimide
  • the electrolyte is KFSI, and the concentration of the electrolyte is 1 mol/L.
  • the organic solvent includes one or more of esters, sulfones, ethers, and nitrile organic solvents.
  • the organic solvent includes propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, One or more of dimethyl sulfone and dimethyl ether.
  • the electrolyte is 1 mol/L potassium bisfluorosulfonimide dissolved in ethylene glycol dimethyl ether (DME).
  • DME ethylene glycol dimethyl ether
  • the polycarboxylic acid potassium salt/graphite composite material is obtained by using polycarboxylic acid, potassium source and graphite materials as raw materials, organic liquids such as alcohols as solvents, and hydrothermal reaction. Utilize abundant carboxylate active sites to store potassium ions, and at the same time, introduce graphite-like materials as supports, which is conducive to the kinetic performance of electron transfer, and at the same time prevents the powdering of particles during the cycle, thereby improving the electrical conductivity. chemical properties.
  • the present invention adopts the above-mentioned technical scheme, and its beneficial effects are: one of the objects of the present invention is to provide a new method for synthesizing potassium polycarboxylate/graphite composite material, the preparation method is synthesized in one step, the operation is simple, and the synthesis method has The raw materials needed are abundant and cheap.
  • the second purpose of the present invention is to solve the problem of low rate performance of existing electrodes.
  • the potassium polycarboxylate/graphite composite material is a nanosheet structure, which provides a convenient potassium ion diffusion channel, which is beneficial to improve the diffusion kinetics, thereby improving the battery rate performance.
  • the third purpose of the present invention is to solve the problems that the existing organic electrodes have few active sites and low theoretical potassium storage capacity.
  • the synthesized potassium polycarboxylate/graphite composite material has abundant potassium storage sites, therefore, the theoretical potassium storage capacity is higher, which can better meet the actual needs.
  • the fourth purpose of the present invention is to solve the problems of poor cycle stability, low rate capability and low Coulombic efficiency of the existing electrodes due to severe volume expansion and pulverization.
  • the use of graphite materials as a support can effectively alleviate the volume expansion problem of organic salts during the charging and discharging process, thereby improving the stability, rate performance and Coulomb efficiency of the electrode.
  • a new method for synthesizing potassium polycarboxylate/graphite composite material is provided, which adopts a one-step method, has simple preparation steps, and has abundant raw material sources and low price.
  • the synthesized potassium polycarboxylate/graphite composite material is a two-dimensional nanosheet layer of potassium polycarboxylate dispersed on the graphite surface, with a high specific surface area, which not only promotes the contact between the electrode and the electrode liquid, but also greatly shortens the potassium
  • the transport path of ions reduces the diffusion energy barrier and improves the reaction kinetics.
  • the synthesized potassium polycarboxylate has abundant potassium storage sites, so the theoretical capacity of potassium storage is higher, which can better meet the actual needs.
  • the synthesized potassium polycarboxylate/graphite composite material, supported by graphite materials, can effectively alleviate the volume expansion problem of the organic salt structure, thereby improving the stability, rate capability and Coulomb efficiency of the electrode.
  • Fig. 1 is the Fourier transform infrared spectroscopy (FT-IR) of the potassium tetracarboxylate/graphite composite.
  • FIG. 2 is a scanning electron microscope (SEM) and an energy X-ray spectrum (EDS) image of the potassium tetracarboxylate/graphite composite material.
  • Figure 4 shows the long-cycle performance of the potassium ion half-cell of the potassium tetracarboxylate/graphite composite anode material at a current density of 500 mA/g.
  • an embodiment of the present invention provides a method for preparing a potassium ion battery based on a polycarboxylate potassium salt graphite composite negative electrode material.
  • Example 1 Preparation of potassium tetracarboxylate/reduced graphene oxide (K 4 PM/RGO) composite material (best), the steps are as follows:
  • potassium tetracarboxylate/graphite composite material, conductive carbon black, and PVDF are evenly mixed together according to the mass ratio of 6:3:1, hand milled for 30 minutes, and NMP is added to make a paste slurry. It is evenly coated on the copper foil, and then vacuum-dried at 70 degrees Celsius; after rolling the dried copper foil, it is cut into 10mm diameter discs and used as a negative electrode.
  • step (1) of Example 1 1,2,4,5-benzenetetracarboxylic acid was replaced with 1,3,5-benzenetricarboxylic acid (Comparative Example 3), benzenepentacarboxylic acid (Comparative Example 4), benzene Hexacarboxylic acid (Comparative Example 5), Pyrazinetetracarboxylic acid (Comparative Example 6), Pyrimidinetetracarboxylic acid (Comparative Example 7), Pyrantetracarboxylic acid (Comparative Example 8), Pyrroletetracarboxylic acid (Comparative Example 8) Example 9), thiophene tetracarboxylic acid (Comparative Example 10), pyridinetetracarboxylic acid (Comparative Example 11), etc., the obtained products were potassium 1,3,5-benzenetricarboxylate (Comparative Example 3), benzene Potassium Pentaformate (Comparative Example 4), Potassium Mellitic Acid (Comparative Example 5), Pot
  • the test results are as follows.
  • step (1) of Example 1 graphene oxide was replaced with graphite (Comparative Example 12), expanded graphite (Comparative Example 13), graphene (Comparative Example 14), and multi-layer graphene (Comparative Example 15) ) etc., the products obtained are respectively potassium polycarboxylate/graphite (Comparative Example 12), potassium polycarboxylate/expanded graphite (Comparative Example 13), potassium polycarboxylate/graphene (Comparative Example 14) , Potassium polycarboxylate/multilayer graphene (Comparative Example 15)
  • the test results are as follows.
  • K 4 PM/RGO potassium tetracarboxylate/reduced graphene oxide
  • the molar ratio of tetracarboxylic acid and KOH is changed.
  • the morphology of the product will be significantly changed, and at the same time, the specific surface area of the product will be changed, which directly affects the electrochemical properties.
  • K 4 PM/RGO potassium tetracarboxylate/reduced graphene oxide
  • This comparative example is to change the amount of graphene oxide added.
  • the amount of graphene oxide added is low, the proportion of organic tetracarboxylate dispersed on graphene is small, which cannot effectively alleviate the volume expansion of the electrode. Therefore, During cycling, the stability of the electrode is weakened.
  • K 4 PM/RGO potassium tetracarboxylate/graphite
  • the reaction temperature is changed.
  • the reaction temperature is lowered, the reduction of graphene oxide is incomplete, resulting in poor conductivity of the electrode.
  • the reaction temperature is low, the morphology of the product will change, and its specific surface area will be changed. reduce. resulting in lower electrode capacity.

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Abstract

本发明提供一种基于多羧酸钾盐石墨复合负极材料的制备及钾离子电池应用，属于电池技术领域，通过以多羧酸、钾源和石墨类材料为原料，醇类等有机液体为溶剂，通过水热反应，得到多羧酸钾盐/石墨复合材料。利用丰富的羧酸盐活性位点，储存钾离子，同时，引入石墨类材料作为支撑，有利于电子的传输动力学性能，与此同时也防止在循环过程中颗粒的粉化，从而提升了电化学性能。提供一种合成多羧酸钾盐/石墨复合材料的新方法，采用一步法，制备步骤简单，该物质所需要的原料来源丰富、价格廉价。合成的多羧酸钾盐/石墨复合材料，以石墨类材料为支撑，可以有效缓解有机盐结构的体积膨胀问题，从而提升电极的稳定性、倍率性能和库伦效率。

Description

一种基于多羧酸钾盐石墨复合负极材料的制备及钾离子电池应用 技术领域
本发明属于电池技术领域，具体涉及一种基于多羧酸钾盐石墨复合负极材料的制备及钾离子电池应用。
背景技术
近年来，可充电的锂离子电池因为高能量密度和长循环稳定性，已经占据了3C产品及电动车等领域储能器件的主要市场。然而，日益增长的储能需求及锂资源的匮乏制约了锂离子电池在可持续社会的进一步发展。因此，开发下一代储能器件对于后锂时代可持续的能源存储及转化具有重要意义。尽管钾离子(-2.93Vvs.标准电极电势)展现了比锂离子(-3.04Vvs.标准电极电势)更高的还原电势，但是钾离子电池因为钾储量丰富、价格低廉的优势，受到了广泛关注，有望成为替代锂离子电池的下一代储能器件。然而，钾离子半径比锂离子大，诱导产生了缓慢的离子扩散动力学，并造成宿主材料结构膨胀，导致电池容量的衰减。因此，寻找合适的储钾材料对于钾离子电池的进一步发展具有重大意义。
当前，尽管众多无机类材料已经尝试用于钾离子存储，比如：插层型石墨或碳材料、转化型过渡金属硫属化合物和合金型金属材料等，但是，这些材料储钾后，普遍存在体积膨胀及粉化等情况，从而造成电池循环稳定性差、库伦效率低及倍率性能差等问题(Chem,2020,6,2442-2460)。为此，科研工作者也开始探索用有机类材料作为钾离子存储电极材料，例如：対苯二甲酸钾能够可逆存储两个钾离子，并且减少钾枝晶产生，保障了电池安全性，但是其钾离子存储位点较少，理论容量较低(Mater.Today Energy,2020,17,100454)。三嗪基共价有机框架也可以用于钾离子存储，但是其循环稳定性较差，循环寿命低。(ACS Nano,2019,13,14252-14261)。
现有的钾离子电池负极材料包括插层型石墨或碳材料、合金型金属和转化型过渡金属氧化物及硫化物，以及部分有机物等。其中，碳材料中钾离子的扩散速率缓慢且碳材料结构易膨胀及粉化，导致较低的库伦效率，较差的电池稳定性和倍率性能；金属氧化物、硫化物，由于中间体的溶解和导电性差，从而导致差的循环稳定性和低的容量保持率；对于常规的金属锡、锑、铋等负极，由于在循环过程中严重的体积膨胀，容易造成电极粉化现象，从而导致循环性能差、库伦效率低等问题；而报道的有机材料存在活性位点少，理论容量低且稳定性差等问题。
发明内容
有鉴于此，本发明的目的在于针对现有技术的不足，本发明提供一种基于多羧酸钾盐/石墨(以1,2,4,5-均苯四甲酸钾/还原氧化石墨烯，K 4PM/RGO为例)负极材料的制备方法及其在新型二次钾离子电池的应用。
一种基于多羧酸钾盐石墨复合负极材料，多羧酸钾盐分散在石墨类材料表面，多羧酸钾盐纳米片的边长1-5微米，石墨投料含量为50mg/L。
优选的，所述多羧酸结构通式如下(此处为四羧酸结构)，羧酸结构可以为三个、四个、五个或六个或n个羧酸，其中R基为苯环、吡啶环、吡嗪环、嘧啶环、吡喃环、吡咯环、噻吩、呋喃。
Figure PCTCN2020134647-appb-000001
优选的，所述R基为苯环。
一种基于多羧酸钾盐石墨复合负极材料的制备方法，包括步骤如下：
步骤101：取摩尔比为(4-0.125)的多羧酸和钾源(盐或碱)分别溶解在溶剂中，磁力搅拌1-2小时；分别标记A溶液和B溶液；其中B溶液中加入石墨类材料，混合均匀；
步骤102：将上述搅拌好的A溶液和B溶液混合到一起，得到混合液C，其中加入顺序为A加入到B溶液中，搅拌1-2小时，将得到的混合液C倒入聚四氟乙烯内衬，并放入反应釜中，将反应釜转入烘箱中反应，温度80-200摄氏度，反应时间6-24小时，等反应结束后降到室温；
步骤103：将上述反应后的混合液C用离心机离心，转速6000-10000转/分钟,时间8-12分钟，然后用乙醇洗涤、离心重复3-5次，放入烘箱真空干燥，温度60-80摄氏度，时间12-48小时，最后得到多羧酸钾盐/石墨复合负极材料。
优选的，所述步骤101中的钾源(盐或碱)为硝酸钾、氯化钾、硫酸钾或氢氧化钾。
优选的，所述钾源为氢氧化钾。
优选的，所述步骤101中的溶剂为乙醇、乙二醇、丙三醇、N-N二甲基甲酰胺、二甲基亚砜、丙酮有机溶剂。
优选的，溶剂为乙醇与乙二醇混合溶液，体积比为1:1。
优选的，所述步骤101中的石墨类材料为石墨、膨胀石墨、石墨烯、多层石墨烯或者氧化石墨烯。
优选的，所述石墨类材料为氧化石墨烯。
优选的，所述步骤101中的多羧酸和氢氧化钾摩尔比为1/8，浓度分别为10和80mmol/L，所加石墨类材料的含量为50mg/L。
优选的，所述步骤102中反应釜内衬容积为250ml；反应釜的温度为180摄氏度，反应时间为12小时。
优选的，所述步骤103中，离心转速为9000转/分钟，时间为10分钟，干燥温度为70摄氏度，时间为24小时。
一种基于多羧酸钾盐石墨复合负极材料的应用，应用于锂、钠、钾、钙离子电池，作为锂、钠、钾、钙离子电池的负极材料使用。
一种基于多羧酸钾盐石墨复合负极材料的钾离子电池，包括金属钾片、钾离子半电池负极片、隔膜、电解液及外壳，所述的负极片分别将活性材料、导电剂、粘结剂混合后再加入有机溶剂，磨成浆料后涂覆于集流体得到；负极片中活性材料为多羧酸钾盐/石墨复合材料。
一种基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，包括以下步骤：将多羧酸钾盐/石墨复合材料、导电剂、粘结剂按质量比6:3:1的比例混合后再加入氮甲基吡咯烷酮，磨成浆料后涂覆于铜箔上，涂覆后于70摄氏度下真空干燥24小时，切割成极片。
优选的，电解液包括无机钾盐、有机钾盐中的一种或几种，可以分解成K +和阴离子，隔膜材料为玻璃纤维。
优选的，电解液为KPF 6、K 2SO 4、KBH 4、KBF 4、KClO 4、双三氟甲基磺酰亚胺钾(KTFSI)或双氟磺酰亚胺钾(KFSI)中的一种或几种，电解液的浓度为0.5-5mol/L。
优选的，电解液为KFSI，电解液的浓度为1mol/L。
优选的，有机溶剂包括酯类、砜类、醚类、腈类有机溶剂中的一种或几种。
优选的，有机溶剂包括碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、氟代碳酸乙烯酯、乙二醇二甲醚、二乙二醇二甲醚、二甲基砜、二甲醚中的一种或多种。
优选的，电解液为1mol/L双氟磺酰亚胺钾溶于乙二醇二甲醚(DME)。
本发明通过以多羧酸、钾源和石墨类材料为原料，醇类等有机液体为溶剂，通过水热反应，得到多羧酸钾盐/石墨复合材料。利用丰富的羧酸盐活性位点，储存钾离子，同时，引入石墨类材料作为支撑，有利于电子的传输动力学性能，与此同时也防止在循环过程中颗粒的粉化，从而提升了电化学性能。
本发明采用上述技术方案，其有益效果在于：本发明的目的之一在于提供一种合成多羧酸钾盐/石墨复合材料的新方法，该制备方法一步合成，操作简单，而且该合成方法所需要的原材料储量丰富，价格廉价。
本发明的目的之二在于解决现有电极倍率性能低的问题。多羧酸钾盐/石墨复合材料是纳米片层结构，提供了便捷的钾离子扩散通道，有利于提升扩散动力学，从而提升电池倍率性能。
本发明的目的之三在于解决现有有机类电极活性位点少，理论储钾容量低的问题。合成的多羧酸钾盐/石墨复合材料具有丰富的储钾位点，因此，储钾理论容量较高，更能满足实际需求。
本发明的目的之四在于解决现有电极由于严重的体积膨胀及粉化导致的循环稳定性差、倍率性能低、库伦效率低的问题。采用石墨类材料作为支撑，在充放电过程可以有效缓解有机盐的体积膨胀问题，从而提升电极的稳定性、倍率性能及库伦效率。
本发明的优点：1)提供一种合成多羧酸钾盐/石墨复合材料的新方法，采用一步法，制备步骤简单，该物质所需要的原料来源丰富、价格廉价。
2)合成的多羧酸钾盐/石墨复合材料为二维纳米片层多羧酸钾盐分散在石墨表面，具有较高比表面积，不仅促进了电极与电极液的接触，而且极大地缩短钾离子的传输路径，降低扩散能垒，提升反应动力学。
3)合成的多羧酸钾盐具有丰富的储钾位点，因此，储钾理论容量较高，更能满足实际需求。
4)合成的多羧酸钾盐/石墨复合材料，以石墨类材料为支撑，可以有效缓解有机盐结构的体积膨胀问题，从而提升电极的稳定性、倍率性能和库伦效率。
附图说明
图1为四羧酸钾盐/石墨复合材料的傅里叶红外光谱图(FT-IR)。
图2为四羧酸钾盐/石墨复合材料扫描电子显微镜图(SEM)及X射线能谱图(EDS)。
图3为四羧酸钾盐/石墨复合负极材料的钾离子半电池在不同电流密度下的充放电曲线。(1C＝100mA/g)
图4为四羧酸钾盐/石墨复合负极材料的钾离子半电池在500mA/g电流密度条件下的长循环性能。
具体实施方式
请参看图1至图4，本发明实施例提供了一种基于多羧酸钾盐石墨复合负极材料的钾离子电池制备方法。
多羧酸钾盐/石墨复合材料的制备具体实施例：
实施例1：四羧酸钾盐/还原氧化石墨烯(K 4PM/RGO)复合材料的制备(最佳)，步骤如下：
(1)称量1.25mmol的1,2,4,5-苯四羧酸溶解在100ml无水乙醇中标记为A溶液；称量10mmol的KOH和10mg氧化石墨烯溶解于50ml无水乙醇和50ml乙二醇的混合溶液中，标记为B溶液，分别磁力搅拌1小时；
(2)将搅拌好的溶液混合到一起，其中加入顺序为A加入到B溶液中，标记为C溶液，搅拌2小时，将C溶液转入250ml聚四氟乙烯内衬，并放入反应釜中，将反应釜放入烘箱中反应，温度180摄氏度，反应时间12小时，等反应降到室温；
(3)将反应液用离心机离心，转速9000转/分钟,时间10分钟。然后用乙醇洗涤、离心重复3次，放入烘箱真空干燥，温度70摄氏度，时间24小时。最后得到K 4PM/RGO复合负极材料。
组装钾离子半电池具体实例(最佳):
制备负极：四羧酸钾盐/石墨复合材料、导电炭黑、PVDF按照质量比6:3:1均匀混合在一起，手磨30分钟，加入NMP制成糊状浆料，然后，把浆料均匀涂覆在铜箔上，接着在70摄氏度下真空干燥；把干燥过的铜箔滚压后，裁切成直径10mm的圆片后作为负极备用
制备对电极：钾片裁切成直径12mm的圆片后作为对电极备用。
制备隔膜：将玻璃纤维膜裁切成直径16mm的圆片后作为隔膜备用。
配制电解液：称取3mmol KFSI加入到3ml的DME溶剂中，搅拌至KFSI完全溶解，充分搅拌均匀后作为电解液备用。
组装：在惰性气体保护的手套箱中，将上述制备好的正极、隔膜、负极依次紧密堆叠，滴加电解液使隔膜完全浸润，然后将上述堆叠部分封装入扣式壳体，完成钾基半电池的组装。
对比实施例2
四羧酸钾盐(K 4PM)的制备，步骤如下：
(1)称量1.25mmol的1,2,4,5-苯四羧酸溶解在100ml无水乙醇中标记为A溶液；称量10mmol的KOH溶解于100ml无水乙醇溶液中，标记为B溶液，分别磁力搅拌1小时；
(2)将搅拌好的溶液混合到一起，其中加入顺序为A加入到B溶液中，标记为C溶液，搅拌2小时，将C溶液转入250ml聚四氟乙烯内衬，并放入反应釜中，将反应釜放入烘箱中反应，温度180摄氏度，反应时间12小时，等反应降到室温；
(3)将反应液用离心机离心，转速9000转/分钟,时间10分钟。然后用乙醇洗涤、离心重复3次，放入烘箱真空干燥，温度70摄氏度，时间24小时。最后得到K 4PM/RGO复合负极材料。
该对比例是制备单一的有机四羧酸钾盐，不加入石墨类材料，该材料存在严重的团聚现象，而且结构稳定性差，电池循环稳定性不理想。
对比实施例3-11
多羧酸钾盐的制备：
将实施例1的步骤(1)中1,2,4,5-苯四羧酸换成1,3,5-苯三甲酸(对比例3)、苯五甲酸(对比实施例4)、苯六甲酸(对比实施例5)、吡嗪四羧酸(对比实施例6)、嘧啶四羧酸(对比实施例7)、吡喃四羧酸(对比实施例8)、吡咯四羧酸(对比实施例9)、噻吩四羧酸(对比实施例10)、吡啶四羧酸(对比实施例11)等，所得产物分别为1,3,5-苯三甲酸钾(对比实施例3)、苯五甲酸钾(对比实施例4)、苯六甲酸钾(对比实施例5)、吡嗪四羧酸钾(对比实施例6)、嘧啶四羧酸钾(对比实施例7)、吡喃四羧酸钾(对比实施例8)、吡咯四羧酸钾(对比实施例9)、噻吩四羧酸钾(对比实施例10)吡啶四羧酸钾(对比实施例11)
将上述实施例电芯采用0.5C(1C＝100mAg -1)的充放电倍率，在电压范围为0.01～3V条件下，进行充放电测试，其测试结果如下。
表1.本发明实施例1和对比实施例2-9电池测试数据
Figure PCTCN2020134647-appb-000002
对比实施例12-15
多羧酸钾盐/石墨类复合材料的制备：
将实施例1的步骤(1)中氧化石墨烯换成石墨(对比实施例12)、膨胀石墨(对比实施例13)、石墨烯(对比实施例14)、多层石墨烯(对比实施例15)等，所得产物分别为多羧酸钾盐/石墨(对比实施例12)、多羧酸钾盐/膨胀石墨(对比实施例13)、多羧酸钾盐/石墨烯(对比实施例14)、多羧酸钾盐/多层石墨烯(对比实施例15)
将上述实施例电芯采用0.5C(1C＝100mAg -1)的充放电倍率，在电压范围为0.01～3V条件下，进行充放电测试，其测试结果如下。
表2.本发明实施例1和对比实施例12-15电池测试数据
Figure PCTCN2020134647-appb-000003
对比实施例16
四羧酸钾盐/还原氧化石墨烯(K 4PM/RGO)复合材料的制备，步骤如下：
(1)称量5mmol的1,2,4,5-苯四羧酸溶解在100ml无水乙醇中标记为A溶液；称量5mmol的KOH和10mg氧化石墨烯溶解于50ml无水乙醇和50ml乙二醇的混合溶液中，标记为B溶液，分别磁力搅拌1小时；
(2)将搅拌好的溶液混合到一起，其中加入顺序为A加入到B溶液中，标记为C溶液，搅拌2小时，将C溶液转入250ml聚四氟乙烯内衬，并放入反应釜中，将反应釜放入烘箱中反应，温度180摄氏度，反应时间12小时，等反应降到室温；
(3)将反应液用离心机离心，转速9000转/分钟,时间10分钟。然后用乙醇洗涤、离心重复3次，放入烘箱真空干燥，温度70摄氏度，时间24小时。最后得到K 4PM/RGO复合负极材料。
该对比例是在改变四羧酸与KOH的摩尔比，通过改变四羧酸和KOH的摩尔比，产物形貌会发生明显改变，同时，产物比表面积会发生改变，从而直接影响电化学性质。
对比实施例17
四羧酸钾盐/还原氧化石墨烯(K 4PM/RGO)复合材料的制备，步骤如下：
(1)称量1.25mmol的1,2,4,5-苯四羧酸溶解在100ml无水乙醇中标记为A溶液；称量10mmol的KOH和5mg氧化石墨烯溶解于50ml无水乙醇和50ml乙二醇的混合溶液中，标记为B溶液，分别磁力搅拌1小时；
(2)将搅拌好的溶液混合到一起，其中加入顺序为A加入到B溶液中，标记为C溶液，搅拌2小时，将C溶液转入250ml聚四氟乙烯内衬，并放入反应釜中，将反应釜放入烘箱中反应，温度180摄氏度，反应时间12小时，等反应降到室温；
(3)将反应液用离心机离心，转速9000转/分钟,时间10分钟。然后用乙醇洗涤、离心重复3次，放入烘箱真空干燥，温度70摄氏度，时间24小时。最后得到K 4PM/RGO复合负极材料。
该对比例是在改变氧化石墨烯的加入量，当氧化石墨烯的加入量较低时，有机的四羧酸盐分散在石墨烯上的比例较少，无法有效缓解电极的体积膨胀，因此，电极在循环过程中，稳定性有所减弱。
对比实施例18
四羧酸钾盐/石墨(K 4PM/RGO)复合材料的制备，步骤如下：
(1)称量1.25mmol的1,2,4,5-苯四羧酸溶解在100ml无水乙醇中标记为A溶液；称量10mmol的KOH和10mg氧化石墨烯溶解于50ml无水乙醇和50ml乙二醇的混合溶液中，标记为B溶液，分别磁力搅拌1小时；
(2)将搅拌好的溶液混合到一起，其中加入顺序为A加入到B溶液中，标记为C溶液，搅拌2小时，将C溶液转入250ml聚四氟乙烯内衬，并放入反应釜中，将反应釜放入烘箱中反应，温度100摄氏度，反应时间12小时，等反应降到室温；
(3)将反应液用离心机离心，转速9000转/分钟,时间10分钟。然后用乙醇洗涤、离心重复3次，放入烘箱真空干燥，温度70摄氏度，时间24小时。最后得到K 4PM/RGO复合负极材料。
该对比例是在改变反应温度，当反应温度降低时，氧化石墨烯的还原不完全，会造成电极的导电性较差，同时，反应温度低时，产物的形貌会发生改变，其比表面积降低。造成电极容量较低。
以上所揭露的仅为本发明较佳实施例而已，当然不能以此来限定本发明之权利范围，本领域普通技术人员可以理解实现上述实施例的全部或部分流程，并依本发明权利要求所作的等同变化，仍属于发明所涵盖的范围。

Claims (22)

  1. 一种基于多羧酸钾盐石墨复合负极材料，其特征在于：多羧酸钾盐分散在石墨类材料表面，多羧酸钾盐纳米片的边长为1-5微米，石墨投料含量为50mg/L。
  2. 如权利要求1所述的一种基于多羧酸钾盐石墨复合负极材料，其特征在于：所述多羧酸结构通式如下(此处为四羧酸结构)，羧酸结构为三个、四个、五个或六个或n个羧酸，其中R基为苯环、吡啶环、吡嗪环、嘧啶环、吡喃环、吡咯环、噻吩、呋喃。
    Figure PCTCN2020134647-appb-100001
  3. 如权利要求2所述的一种基于多羧酸钾盐石墨复合负极材料，其特征在于：所述R基为苯环。
  4. 一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：包括步骤如下：
    步骤101：取摩尔比为(4-0.125)的多羧酸和钾源(盐或碱)分别溶解在溶剂中，磁力搅拌1-2小时；分别标记A溶液和B溶液；其中B溶液中加入石墨类材料，混合均匀；
    步骤102：将上述搅拌好的A溶液和B溶液混合到一起，得到混合液C，其中加入顺序为A加入到B溶液中，搅拌1-2小时，将得到的混合液C倒入聚四氟乙烯内衬，并放入反应釜中，将反应釜转入烘箱中反应，温度80-200摄氏度，反应时间6-24小时，等反应结束后降到室温；
    步骤103：将上述反应后的混合液C用离心机离心，转速6000-10000转/分钟,时间8-12分钟，然后用乙醇洗涤、离心重复3-5次，放入烘箱真空干燥，温度60-80摄氏度，时间12-48小时，最后得到多羧酸钾盐/石墨复合负极材料。
  5. 如权利要求4所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述步骤101中的钾源(盐或碱)为硝酸钾、氯化钾、硫酸钾或氢氧化钾。
  6. 如权利要求5所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述钾源为氢氧化钾。
  7. 如权利要求4所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述步骤101中的溶剂为乙醇、乙二醇、丙三醇、N-N二甲基甲酰胺、二甲基亚砜、丙酮有机溶剂。
  8. 如权利要求7所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：溶剂为乙醇与乙二醇混合溶液，体积比为1:1。
  9. 如权利要求4所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述步骤101中的石墨类材料为石墨、膨胀石墨、石墨烯、多层石墨烯或者氧化石墨烯。
  10. 如权利要求9所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述石墨类材料为氧化石墨烯。
  11. 如权利要求4所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述步骤101中的多羧酸和氢氧化钾摩尔比为1/8，浓度分别为10和80mmol/L，所加石墨类材料的含量为50mg/L。
  12. 如权利要求4所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述步骤102中反应釜内衬容积为250ml；反应釜的温度为180摄氏度，反应时间为12小时。
  13. 如权利要求4所述的一种基于多羧酸钾盐石墨复合负极材料的制备方法，其特征在于：所述步骤103中，离心转速为9000转/分钟，时间为10分钟，干燥温度为70摄氏度，时间为24小时。
  14. 一种基于多羧酸钾盐石墨复合负极材料的应用，其特征在于：应用于锂、钠、钾、钙离子电池，作为锂、钠、钾、钙离子电池的负极材料使用。
  15. 一种基于多羧酸钾盐石墨复合负极材料的钾离子电池，其特征在于：包括金属钾片、钾离子半电池负极片、隔膜、电解液及外壳，所述的负极片分别将活性材料、导电剂、粘结剂混合后再加入有机溶剂，磨成浆料后涂覆于集流体得到；负极片中活性材料为多羧酸钾盐/石墨复合材料。
  16. 一种如权利要求15所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：包括以下步骤：将多羧酸钾盐/石墨复合材料、导电剂、粘结剂按质量比6:3:1的比例混合后再加入氮甲基吡咯烷酮，磨成浆料后涂覆于铜箔上，涂覆后于70摄氏度下真空干燥24小时，切割成极片。
  17. 一种如权利要求15所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：电解液包括无机钾盐、有机钾盐中的一种或几种，可以分解成K +和阴离子，隔膜材料为玻璃纤维。
  18. 一种如权利要求15所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：电解液为KPF 6、K 2SO 4、KBH 4、KBF 4、KClO 4、双三氟甲基磺酰亚胺钾(KTFSI)或双氟磺酰亚胺钾(KFSI)中的一种或几种，电解液的浓度为0.5-5mol/L。
  19. 一种如权利要求15所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：电解液为KFSI，电解液的浓度为1mol/L。
  20. 一种如权利要求15所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：有机溶剂包括酯类、砜类、醚类、腈类有机溶剂中的一种或几种。
  21. 一种如权利要求20所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：有机溶剂包括碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、氟代碳酸乙烯酯、乙二醇二甲醚、二乙二醇二甲醚、二甲基砜、二甲醚中的一种或多种。
  22. 一种如权利要求21所述的基于多羧酸钾盐石墨复合负极材料的钾离子电池的制备方法，其特征在于：电解液为1mol/L双氟磺酰亚胺钾溶于乙二醇二甲醚(DME)。
PCT/CN2020/134647 2020-12-08 2020-12-08 一种基于多羧酸钾盐石墨复合负极材料的制备及钾离子电池应用 WO2022120592A1 (zh)

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