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A two-layer or multi-layer polymer electrolyte and a battery

An electrolyte and polymer technology, applied in the field of double-layer polymer electrolyte, can solve the problems of reducing battery energy density and cycle performance, difficulty reaching 300Wh/kg, and violating solid-state batteries, etc., to assist lithium ion transport and avoid reaction loss , Promote the effect of lithium salt dissolution

Active Publication Date: 2018-12-07
周伟东
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the oxidation potential of PEO in practical batteries is lower than 4 V, which can only be compared with low-voltage cathodes (such as LiFePO 4 ) match, if with high voltage LiCoO 2 The positive contact is easily oxidized, which violates the original intention of using solid-state batteries to increase energy density, and it is difficult to meet the demand of 300Wh / kg
Therefore, although metal lithium solid-state batteries based on polymer electrolytes have the advantages of high energy density and high safety performance, the electrochemical window of the polymer electrolyte is narrow, and it is easy to be catalyzed by high-voltage positive electrodes and reduced by metal lithium negative electrodes. Reduce the energy density and cycle performance of the battery

Method used

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  • A two-layer or multi-layer polymer electrolyte and a battery
  • A two-layer or multi-layer polymer electrolyte and a battery
  • A two-layer or multi-layer polymer electrolyte and a battery

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Embodiment 1

[0052] The double-layer electrolyte structure provided by this embodiment is as figure 1 shown. In this embodiment, there is a double-layer electrolyte composed of two layers of polymer electrolytes between the positive electrode and the negative electrode, wherein the positive electrode is lithium cobaltate (LiCoO 2 , LCO), the negative electrode is lithium metal. The first layer of polymer electrolyte is a solid electrolyte that is electrochemically stable to high voltage, and it is in contact with the positive electrode. The polymer electrolyte used is poly(N-methyl-malonic amide (Poly(N-methyl-malonic amide, PMA); the second polymer electrolyte layer is a solid electrolyte that is electrochemically stable at low voltage, which is in contact with the negative electrode, and the polymer electrolyte used is polyethylene oxide (PEO) containing lithium salt.

[0053] figure 1 A schematic diagram of the double-layer electrolyte structure.

[0054] In conventional liquid Li-i...

Embodiment 2

[0059] Performance Test of Double Layer Solid Electrolyte Membrane

[0060] Differential scanning calorimeter (DSC) was used to test DLPSE, and the two endothermic peaks obtained in the range of 65-85 °C corresponded to the melting points of the PEO layer and the PMA layer (such as figure 2 shown).

[0061] figure 2 Show the DSC curve graph of PEO, PMA and PEO / PMA three kinds of polymers, image 3 The ion conductivities of PEO, PMA and PEO / PMA three polymers at different temperatures are shown.

[0062] image 3 The ionic conductivities of PEO-Li thin films, PMA-Li thin films and DLPSE at different temperatures (25-65°C) are shown. We can notice that the ionic conductivity of DLPSE in the high temperature region (50–65°C) is between that of PEO-Li and PMA-Li, which indicates that due to the good adhesion between the polymers, PEO-Li and PMA-Li The interface resistance is sufficiently low. Such as image 3 As shown, the conductivity of the dry PMA-Li film at 65 °C is a...

Embodiment 3

[0066] Performance testing of all-solid-state lithium-ion batteries

[0067] To evaluate the electrochemical performance of double-layer electrolytes for practical batteries, we assembled the Li / DLPSE / LiCoO 2 Battery.

[0068] Figure 8 Li / DLPSE / LiCoO 2 The voltage curve of the battery in the first 5 weeks and 100 weeks, the voltage test range is 2.5 ~ 4.2V vs Li / Li + , with a current density of 0.2C (100μA cm -2 ), we can observe that LiCoO 2 The characteristic charge-discharge curves; moreover, the discharge capacity gradually increased in the first 5 weeks due to the electrode infiltration.

[0069] Figure 9 It shows that when the current density is 0.2C, the capacity can be maintained at 108.5mAh g after 100 charge-discharge cycles –1 , up to the highest discharge capacity (119mAh g –1 ), demonstrating the electrochemical stability in charge-discharge cycles.

[0070] Figure 10 It shows that when the current density is 0.1C, 0.2C and 0.5C, the battery capacity ...

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Abstract

The present invention provides a two-layer or multilayer polymer electrolyte comprising a laminated arrangement of a first electrolyte layer for contacting and electrochemically stabilizing a positiveelectrode and a second electrolyte layer for contacting and electrochemically stabilizing a negative electrode. In the two-layer polymer solid electrolyte provided by the invention, a high-voltage stable polymer electrolyte layer is in contact with a positive electrode, and a low-voltage stable polymer electrolyte layer is in contact with a negative electrode. At the same time, the stability conditions of the positive electrode and the negative electrode are satisfied, and a wide redox window is obtained. In addition, the flexibility of the polymer helps to reduce the interfacial resistance.The present invention provides a novel strategy for the design and optimization of solid polymer electrolyte materials, in which a high-voltage positive electrode and a low-voltage metal negative electrode coexist in a battery by utilizing a two-layer structure. This new solid-state electrolyte design will greatly accelerate the development and commercialization of solid-state secondary batteries.

Description

technical field [0001] The invention belongs to the technical field of batteries, and mainly relates to a double-layer polymer electrolyte and a battery including the double-layer polymer electrolyte. Background technique [0002] With the increasing demand for high-energy-density batteries, traditional lithium-ion battery electrode materials are difficult to meet the energy requirements of electric vehicles, so electrode materials with high specific energy need to be considered. For now, only improving the energy density of cathode materials can no longer meet the demand. Using metal lithium instead of traditional graphite carbon anode can greatly improve the energy density of batteries. Therefore, metal lithium batteries have become the focus of next-generation batteries. [0003] The carbonate-based organic liquid electrolyte used in traditional lithium-ion batteries has the lowest unoccupied orbital (Lowest Unoccupied Molecular Orbital, LUMO) of the Fermi level 1.2eV low...

Claims

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Application Information

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IPC IPC(8): H01M10/0565
CPCH01M10/0565H01M2300/0082Y02E60/10
Inventor 周伟东
Owner 周伟东
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