阅读说明：本技术 一种锂离子电池共轭羧酸盐负极材料的制备方法 (Preparation method of conjugated carboxylate negative electrode material of lithium ion battery ) 是由 刘强 卞荣荣 廖圣云 于 2019-09-12 设计创作，主要内容包括：本发明公开了一种锂离子电池共轭羧酸盐负极材料的制备方法,步骤如下：[2,2′：6′,2″-三联吡啶]-4,4′,4″-三甲酸与碱发生中和反应合成[2,2′：6′,2″-三联吡啶]-4,4′,4″-三羧酸锂,与第四周期元素金属钴、镍、铜、锌对应的硝酸盐在60℃下反应5h合成[2,2′：6′,2″-三联吡啶]-4,4′,4″-三羧酸盐。将上述合成材料与乙炔黑、聚偏氟乙烯在N-甲基吡咯烷酮中研磨并涂在铜箔上,烘干后裁片在手套箱里制作扣式电池,并进行电化学性能表征。本发明提供的方法合成的共轭羧酸盐,含有变价金属中心和羧酸根等多个放电位点；此法合成的共轭羧酸盐可以很好发挥羧酸盐、共轭芳香体系和变价金属间的协同储锂效应,提高材料的电化学性能。通过恒流充放电测试发现有较高的放电比容量和优异的循环性能。(The invention discloses a preparation method of a conjugated carboxylate cathode material of a lithium ion battery, which comprises the following steps: [2,2': 6 ', 2' -terpyridine ] -4, 4 '-tricarboxylic acid is subjected to neutralization reaction with a base to synthesize a [2, 2': 6 ', 2' -terpyridine ] -4, 4 '-lithium tricarboxylate is reacted with nitrate corresponding to the fourth phase element cobalt, nickel, copper and zinc at 60 ℃ for 5 hours to synthesize [2, 2': 6 ', 2 "-terpyridine ] -4, 4', 4" -tricarboxylic acid salt. Grinding the synthetic material, acetylene black and polyvinylidene fluoride in N-methyl pyrrolidone, coating the ground material on copper foil, drying the copper foil, cutting the parts into pieces, manufacturing the button cell in a glove box, and characterizing the electrochemical performance. The conjugate carboxylate synthesized by the method provided by the invention contains a plurality of discharge sites such as a valence-variable metal center and carboxylate radical; the conjugated carboxylate synthesized by the method can well play the synergistic lithium storage effect among the carboxylate, a conjugated aromatic system and a valence-variable metal, and the electrochemical performance of the material is improved. The constant current charge and discharge test shows that the material has higher specific discharge capacity and excellent cycle performance.)

1. A preparation method of a conjugated carboxylate cathode material of a lithium ion battery is characterized by comprising the following steps: the conjugate carboxylic acid ligand firstly reacts with alkali to generate conjugate lithium carboxylate, then reacts with nitrate corresponding to the fourth period metal element to synthesize a conjugate carboxylic acid metal compound, and a button cell is manufactured in a glove box for electrochemical performance characterization.

2. The preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: the conjugated carboxylic acid ligand contains 3 pyridines, each of which contains 1 carboxyl group, and is poorly soluble in water.

3. The preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: conjugated carboxylic acid ligand [2, 2': the base used in the acid-base neutralization of 6 ', 2 "-terpyridine ] -4, 4', 4" -tricarboxylic acid is lithium hydroxide, sodium hydroxide, etc.

4. The preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: conjugated lithium carboxylate [2, 2': lithium 6 ', 2 "-terpyridine ] -4, 4', 4" -tricarboxylate is readily soluble in water.

5. the preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: the nitrates corresponding to the metal element in the fourth period are respectively cobalt nitrate hexahydrate, nickel nitrate hexahydrate, copper nitrate hexahydrate and zinc nitrate hexahydrate.

6. The preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: conjugated lithium carboxylate [2, 2': the reaction temperature of the 6 ', 2 ' -terpyridine ] -4, 4 ' -lithium tricarboxylate and the nitrate is 50-80 ℃, and the reaction time is 3-7 h.

7. The preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: the electrolyte used in the battery has the proportion of 1M LiPF₆Solution of (EC/DEC ═ 1: 1), LiPF₆Lithium hexafluorophosphate, EC ethylene carbonate and DEC diethyl carbonate.

8. The preparation method of the conjugated carboxylate negative electrode material of the lithium ion battery according to claim 1, characterized in that: the conjugated carboxylate synthesized by the method is applied to the lithium ion battery cathode material, the first period discharge specific capacity is up to 1567mAh/g, after 200 times of circulation, the discharge specific capacity is 974mAh/g, and the coulombic efficiency is close to 100%.

The technical field is as follows:

The invention belongs to the field of electrochemistry, and relates to a novel lithium ion battery cathode material which is high in discharge specific capacity and excellent in cycle performance. The negative electrode material synthesizes corresponding conjugate carboxylate through the reaction of conjugate carboxylate and nitrate corresponding to the fourth period element metal cobalt, nickel, copper and zinc.

Background of the invention:

in recent years, energy problems and the resulting environmental problems have become the focus of our human attention, traditional energy safety problems and price increases have also made us challenging, and the ever-increasing energy demand and consumption of fossil fuels have led global scientists to attempt to come up with sustainable energy alternatives.

Lithium ion batteries have received great attention as alternative energy sources due to their high energy density, long cycle life and high efficiency. In the organic cathode material, the conjugated carboxylic acid has the advantages of moderate working voltage, large theoretical capacity, long cycle life and the like, but in practical application, the conjugated carboxylic acid has low capacity and poor cycle stability due to poor conductivity and easy dissolution in electrolyte. In order to solve the above problems, the following methods are proposed: (1) the formation of the organic small molecular weight metal salt can maintain the capacity of the organic component and reduce the solubility of the electrode material in the electrolyte due to the formation of ionic bonds; (2) the conjugated system is increased, so that intermolecular electron transmission is facilitated, the chemical stability is improved, and the solubility in organic electrolyte is reduced;

In view of the problems encountered in the charge and discharge processes of the conventional lithium ion battery conjugated carboxylic acid cathode material, in order to realize multi-electron reaction by synergistically utilizing inorganic metal with redox activity and conjugated carboxylate and exert the synergistic lithium storage effect among the carboxylate, a conjugated aromatic system and variable-valence metal, a novel conjugated carboxylate electrode material is designed and synthesized.

The invention content is as follows:

The invention provides a preparation method of a conjugated carboxylate cathode material of a lithium ion battery, and the cathode material prepared by the method has excellent electrochemical performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

(1)[2,2': 6 ', 2 "-terpyridine ] -4, 4 ', 4" -tricarboxylic acid is neutralized with a base to make a soluble [2, 2 ': lithium 6 ', 2 "-terpyridine ] -4, 4', 4" -tricarboxylate;

(2) Reacting the material prepared in the step (1) with nitrates corresponding to the fourth period elements of cobalt, nickel, copper and zinc in deionized water, heating and stirring at 50-80 ℃ for 3-7 h to synthesize [2, 2': 6 ', 2 "-terpyridine ] -4, 4', 4" -tricarboxylic acid salt;

(3) And (3) grinding the material prepared in the step (2), acetylene black and polyvinylidene fluoride according to a certain proportion, coating the ground material on copper foil, drying the copper foil, cutting the pieces into pieces, manufacturing the button cell in a glove box, and characterizing the electrochemical performance.

Further, the base used in step (1) is lithium hydroxide, sodium hydroxide, or the like.

furthermore, the adding amount of the deionized water in the step (2) is 60-100 mL.

Further, the water oxygen value of the glove box in the step (3) is less than 1 ppm.

The invention has the following advantages:

(1) the specific energy density of the active material is improved by increasing a plurality of carboxyl active sites, variable valence metal centers and conjugation degrees, so that the specific capacity of the active material is improved;

(2) the synergistic lithium storage effect among carboxylate, a conjugated aromatic system and variable-valence metals is exerted, and the electrochemical performance of the material is improved.

Description of the drawings:

Fig. 1 is a schematic diagram of a cobaltate synthesis scheme according to an embodiment of the present invention.

Fig. 2 is a diagram of a cobaltate constant current charge-discharge cycle according to an embodiment of the present invention.

The specific implementation mode is as follows:

the present invention is further described by way of examples, which should not be construed as limiting the scope of the invention, and any simple modifications, equivalent substitutions, improvements and the like made to the following examples by those skilled in the art without departing from the technical spirit of the present invention are within the scope of the technical solution of the present invention.