Polymer single ion conductor and preparation method thereof, composite cathode and solid state lithium battery

A lithium-sulfur battery, composite cathode technology, applied in secondary batteries, battery electrodes, non-aqueous electrolyte battery electrodes, etc. It can improve the cycle stability performance, improve the battery coulombic efficiency, and reduce the polarization effect of charge and discharge.

Active Publication Date: 2019-08-16
SAIC MOTOR
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

In this case, the ionic conductance of the electrolyte phase of the electrode is mainly characterized by the movement of anions. For the electrochemical reaction, the mass transfer rate of lithium ions is still insufficient, which makes the charge and discharge polarization effect large, and it is difficult for the battery to operate at a large current. work under density
On the other hand, since the lithium salt in PEO is not completely dissociated, but has a certain degree of dissociation, the migration of lithium ions and anions is also accompanied by the crystallization-dissociation process, which will cause lithium salts to be generated in the electrode. Uneven distribution, local depletion and precipitation on the interface affect the smoothness of the ion conduction path inside the positive electrode

Method used

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  • Polymer single ion conductor and preparation method thereof, composite cathode and solid state lithium battery
  • Polymer single ion conductor and preparation method thereof, composite cathode and solid state lithium battery
  • Polymer single ion conductor and preparation method thereof, composite cathode and solid state lithium battery

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preparation example Construction

[0046] The present invention also provides a method for preparing the above-mentioned polymer single ion conductor, comprising the following steps:

[0047] A) dissolving the carboxyl-containing polymer having the structure of formula (I) in deionized water to obtain an aqueous solution of the carboxyl-containing polymer;

[0048] B) adding lithium hydroxide to the aqueous solution of the carboxyl-containing polymer, mixing and stirring, and reacting to obtain a polymer single ion conductor;

[0049] Specifically, the carboxyl-containing polymer having the structure of formula (I) is dissolved in deionized water to obtain an aqueous solution of the carboxyl-containing polymer; the concentration of the carboxyl-containing polymer in the aqueous solution of the carboxyl-containing polymer is 0.01 wt%-50wt%, preferably 0.1wt%-40wt%, more preferably 1wt%-30wt%, even more preferably 5wt%-25wt%.

[0050] Next, lithium hydroxide was added to the aqueous solution of the carboxyl grou...

Embodiment 1

[0087] Polyacrylic acid (M w =4000000) was dissolved in deionized water to prepare a polyacrylic acid solution with a mass fraction of 1%. According to the stoichiometric ratio of carboxyl group: hydroxide group of 1:1, add lithium hydroxide and stir magnetically for one hour to obtain lithium polyacrylate hydrogel, and the lithium polyacrylate powder obtained after evaporating the solvent is a lithium ion single ion conductor .

[0088]

[0089] lithium polyacrylate

[0090] Take by weighing acetylene black-sulfur composite material (sulfur content=80%wt), VGCF carbon fiber and polyacrylic acid lithium with the mass ratio of 8:1:1, disperse with deionized water, make the slurry solid content be 8%, the slurry The material was ball-milled for 6 hours and evenly coated on aluminum foil, and then vacuum-dried at 60°C for 8 hours to obtain a sulfur cathode. Carry out scanning electron microscope observation to described anode, the result sees figure 1 , figure 1 A scannin...

Embodiment 2

[0093] Polymaleic acid (M w =50000) was dissolved in deionized water to prepare a polymaleic acid solution with a mass fraction of 2%. According to the stoichiometric ratio of carboxyl group: hydroxide group of 1:1, lithium hydroxide was added and magnetically stirred for one hour to obtain polylithium maleate hydrogel.

[0094]

[0095] Lithium polymaleate

[0096] with BF 3 : Li is added to BF at a stoichiometric ratio of 1:1 3 2H 2 O, magnetic stirring evenly. Take by weighing VGCF carbon fiber-sulfur composite material (sulfur content=80%wt) and SuperP with the mass ratio of 17:1, add this hydrogel, make sulfur carbon composite material, the mass ratio of SuperP and polylithium maleate is 17 :1:2, after dispersing with magnetic stirring for 30 minutes, add an appropriate amount of deionized water to make the solid content of the slurry 8%, ball mill the slurry for 8 hours, and evenly coat it on the aluminum foil, and dry it in vacuum at 60°C for 8 Hours later, a s...

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Abstract

The invention provides a polymer single ion conductor which is formed by reacting lithium hydroxide with a carboxyl-containing polymer with a structure shown in a formula (I). The polymer has a main chain structure of -CH2-CH-, the main chain is carried with carboxyl lithium side groups, under the action of a polymer chain segment motion, the carboxyl lithium moves with the main chain, and dissociation and combination of lithium ions between the two carboxyl lithium side groups so as to conduct the lithium ions. After a lithium ion dissociation agent containing BF3 is added, -COO<-<Li<+> forms-COOF3B<->Li<+>, and the dissociation degree of the lithium ions is further improved to improve the dissociation and combination rate of the lithium ions and further improve the lithium ion conductivity.

Description

technical field [0001] The invention belongs to the technical field of solid-state lithium-sulfur batteries, and in particular relates to a polymer single-ion conductor and a preparation method thereof, a composite positive electrode and an all-solid-state lithium-sulfur battery. Background technique [0002] The theoretical specific capacity of lithium-sulfur battery is 1675mAh / g, and the theoretical specific energy is 2600Wh / Kg, which is much higher than that of traditional lithium-ion batteries. At the same time, sulfur reserves are abundant, the price is low, and the pollution and toxicity are low, so the lithium-sulfur battery system has good development potential. However, the lithium polysulfide intermediate produced in its electrochemical reaction can dissolve in the organic electrolyte and cause the shuttle effect, resulting in the loss of active materials, corrosion of lithium metal in the negative electrode, rapid decline in cycle capacity, and reduced Coulombic e...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M4/13H01M10/0525C08F8/44C08F120/06C08F122/02C08F222/02C08F210/02
CPCH01M4/624H01M4/13H01M10/0525C08F8/44C08F120/06C08F122/02C08F222/02C08F210/02Y02E60/10
Inventor 洪晓恒朱冠楠汤艳萍冯奇
Owner SAIC MOTOR
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