Chargeable alkali metal-sulfur liquid flow battery

Abstract

A chargeable alkali metal-sulfur liquid flow battery comprises a positive electrode chamber portion, a diaphragm and a negative electrode chamber portion, wherein the positive electrode chamber portion comprises a positive electrode reaction chamber and a liquid storage tank communicated with a positive electrode chamber pipeline. The positive reaction chamber comprises a positive electrode collector and positive electrode sizing, and the positive electrode sizing used for a positive electrode circulates between the positive electrode reaction chamber and the liquid storage tank. The negative electrode chamber portion comprises a negative electrode reaction chamber comprising a negative electrode, a negative electrode collector and negative electrode electrolyte, and the diaphragm is a single-ion conductor diaphragm and is arranged between the positive electrode reaction chamber and the negative reaction chamber. Only one working ion rather than any other substances such as non-working ions is guaranteed to conduct between the positive electrode and the negative electrode. The positive electrode sizing is composed of positive electrode electrolyte and positive active matters mixed in the positive electrode electrolyte, and the positive active matters are one or more kinds of MxSy (M=Li or Na; 0(x< / =2; 0(y< / =12).

Description

technical field [0001] The present invention relates to a chemical battery. In particular, it relates to an alkali metal-sulfur flow battery. Background technique [0002] Since the successful development of lithium-ion batteries, they have been widely used in portable appliances such as mobile phones, notebook computers and cameras due to their advantages such as good safety, high voltage and specific energy, and long charge and discharge life. With the miniaturization and portability of electronic equipment, and the emergence and vigorous development of green and environmentally friendly electric vehicles, lithium-ion batteries as energy and power sources have put forward higher requirements. How to further improve the specific capacity and high-rate discharge performance of lithium-ion batteries on the existing basis has become a current hot issue. In addition, how to improve the temperature adaptability of electronic and power equipment using lithium-ion battery power ...

AI Technical Summary

Problems solved by technology

[0003] The current commercial use of lithium-ion battery cathode materials is mainly concentrated on transition metal lithium intercalation oxides, including cobalt, iron, nickel, manganese oxides and their doping compounds, but such compounds are limited by their own theoretical capacity. The energy density reaches 300Wh / Kg, and since this material is solid, ions are controlled by diffusion during charge and discharge, so it is difficult to improve the rate performance and there is not much space. In addition, the diffusion process of lithium ions in it is greatly affected by temperature changes , so that the temperature range of lithium-ion batteries is very limited

Lithium-sulfur batteries due to their high energy density (S 8 1675mAh / g), the theoretical energy density can reach 2800Wh / kg, which is considered to be the development direction of lithium-ion batteries in the future, but due to the large technical difficulties in this system, it is still in the laboratory stage

The main problems of its existence are: 1) the charging product elemental sulfur S 8 and the discharge product Li 2 The conductivity of S is similar to that of an insulator, and the conductivity is extremely poor. If it is used as an active material, it needs to be combined with a large number of conductive materials to work, or its particles should be reduced to the nanometer or molecular level.

And as the number of charge and discharge increases, the internal resistance of the battery continues to rise, and the specific energy gradually decreases, which is the main reason for the short cycle life of lithium-sulfur batteries.

2) The reaction of the positive electrode material elemental sulfur charge and discharge process is a multi-step reaction, and the intermediate product Li 2 S 8 , Li 2 S 6 , Li 2 S 4 It is easily soluble in the electrolyte, and the polysulfide ions dissolved in the electrolyte will also shuttle back and forth between the positive and negative electrodes, resulting in low charge and discharge efficiency and large self-discharge

[0007] In the C / 10 rate constant current charge and discharge, the composite material discharges 612mAh / g in the first week, but due to the strong "shuttle effect" overcharge is obvious, the efficiency in the first week is 137%, and the specific capacity retention rate after 50 weeks is only 51%.

Images