Lithium-sulfur battery positive electrode and preparation method thereof

Abstract

The invention discloses a lithium-sulfur battery positive electrode and a preparation method thereof. The preparation method comprises the steps of uniformly mixing a positive active substance, a conducting agent and a bonding agent to obtain a mixture, smearing the mixture on a current collector as an active substance layer, and drying the current collector to obtain a positive substrate; uniformly mixing a conducting agent, a bonding agent and a dispersing agent to obtain a conducting sizing agent, smearing the conducting sizing agent on the outer surface of the positive substrate as a protective layer, and drying the positive substrate to obtain the lithium-sulfur battery positive electrode. The preparation method is simple and easy to operate, easy to control and suitable for industrialized production; in the prepared lithium-sulfur battery positive electrode, the protective layer plays a role of a conducting, sulfur intercepting and electrode stabilizing structure, so that the capacity, multiplying power and cycling stability of a lithium-sulfur battery can be effectively improved, the thickness of the protective layer is easy to control, and the influence on the sulfur content of the positive electrode can be reduced as far as possible.

Description

technical field [0001] The invention relates to the technical field of lithium-sulfur batteries, in particular to a lithium-sulfur battery positive electrode and a preparation method thereof. Background technique [0002] With the growth of population and economy and the improvement of people's living standards, the demand for energy is increasing year by year, and the environmental pollution caused by the use of fossil energy is also becoming more and more serious. In order to reduce dependence on fossil energy, new energy technologies based on renewable energy are rapidly developed and applied. Lithium-sulfur battery is an inexpensive rechargeable battery with high energy density (the theoretical energy density of lithium-sulfur battery is as high as 2600W h kg -1 ), considered to be one of the most attractive battery systems in the future. However, lithium-sulfur battery technology also faces many problems from materials and systems: First, the resistivity of active mat...

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Problems solved by technology

However, lithium-sulfur battery technology also faces many problems from materials and systems: First, the resistivity of active material sulfur is relatively high (5×10 -30 S cm -1 , 25°C); secondly, sulfur will expand in volume during the charge-discharge cycle, leading to the destruction of the sulfur electrode structure; thirdly, the polysulfides formed during the cycle are easy to dissolve in the electrolyte, and the electrode active materials gradually decrease. Lower specific capacity

Other methods improve the utilization of active materials by designing new battery configurations, for example, Arumugam Manthiram et al [Su Y S, Manthiram A. Lithium–sulfur batteries with a microporous carbon paper as a bifunctional interlayer. [J] Nature Communications, 2012, 3: 1166.] A porous conductive interlayer is added between the pole piece and the separator to prevent the shuttle of polysulfide compounds and achieve the purpose of improving the electrochemical performance of lithium-sulfur batteries. However, the addition of the interlayer will increase the quality of the positive electrode, resulting in Low energy density, and the manufacturing process of the interlayer is complicated, which is not conducive to industrial production; the Chinese patent application "a lithium-sulfur battery with an adsorption layer" (application number: 201110092817.2) proposed by Tu Muchun et al. directly on the diaphragm Coating an adsorption layer to achieve the purpose of adsorbing polysulfides to improve the electrochemical performance of lithium-sulfur batteries, however, the method of coating the adsorption layer on the separator is difficult and may cause short circuit of the battery

In addition, the Chinese patent application "a multi-layer structure composite positive electrode for lithium-sulfur secondary battery and its preparation method" (application number: 201210538945.X) proposed by Zhang Kai et al. sputters a layer of Conductive film, the purpose is to play the role of conduction and sulfur interception, but this method is complicated and costly

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