Preparation method of low-temperature sodium-sulfur battery diaphragm and low-temperature sodium-sulfur battery

Abstract

The invention relates to the technical field of sodium batteries, and aims to provide a preparation method of a low-temperature sodium-sulfur battery diaphragm and a low-temperature sodium-sulfur battery. The preparation method comprises the following steps: adding a dendritic microporous PBO diaphragm modified by carbon quantum dots into a poly-sodium sulfide solution; and dipping for 12 hours at 50 DEG C, and carrying out THF washing and drying to obtain the low-temperature sodium-sulfur battery diaphragm treated by the poly-sodium sulfide. According to the invention, high strength and high heat-resistant temperature characteristics of the PBO resin are utilized, and the safety and reliability of the sodium-sulfur battery are greatly improved through the diaphragm with the PBO resin as the raw material. Directional dendritic pore channels are obtained through flash freezing pore forming, so that sodium ion transfer is facilitated. Carbon quantum dots on the walls of the dendritic PBO micropores are beneficial to adsorption of long-chain polysulfide, the adsorption capacity of polysulfide is improved, the concentration gradient of polysulfide is established in the membrane, the content of sodium ions is increased, the internal impedance of the sodium-sulfur battery is reduced, growth of sodium dendrites is passivated so the sodium dendrites are prevented from passing through the diaphragm, the possibility of contact between the sodium dendrites and a positive electrode in the charging and discharging process is eliminated, and short circuit of the battery is prevented.

Description

technical field [0001] The invention relates to the technical field of sodium batteries, in particular to a preparation method of a low-temperature sodium-sulfur battery diaphragm capable of preventing sodium dendrite penetration and polysulfide ion shuttle, and a sodium-sulfur battery. Background technique [0002] Lithium-ion batteries have high energy density and basically no pollution to the environment. They are currently the most widely used secondary batteries. However, the cost of lithium-ion batteries is high and lithium resources are limited, so it is urgent to develop energy storage batteries with abundant resources and low cost. Sodium-sulfur battery is a kind of energy storage battery with high energy density, low cost and abundant resources. Traditional sodium-sulfur batteries work at high temperatures, and the composites of metallic sodium Na and elemental sulfur S and carbon C are used as active materials for the negative and positive electrodes, respectivel...

AI Technical Summary

Problems solved by technology

However, there are problems with sodium-sulfur batteries: (1) high operating temperature; (2) not suitable for intermittent work, the continuous switching of high and low temperatures may easily cause leakage of the stack, and material fatigue damage; (3) the scale of the flow battery should not be too large, etc. question

However, the dendrites generated during the charging and discharging process of the sodium-sulfur battery can easily penetrate the separator and short circuit with the positive electrode, resulting in the extremely poor battery cycle life of the sodium-sulfur battery.

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