Method for suppressing shuttle flying of polysulfide ions in lithium-sulfur battery

Abstract

The invention relates to a method for suppressing shuttle flying of polysulfide ions in a lithium-sulfur battery. A complexing agent is added to a negative electrode electrolyte or a positive electrode of the lithium-sulfur battery; by forming a polysulfide ion complex in the negative electrode of the lithium-sulfur battery, diffusion speed of the polysulfide ions can be lowered and diffusion speed to the negative electrode can be lowered; the complex is formed by the complexing agent and the polysulfide ions in a compounding manner; and the complexing agent can be a nitrogen element-containing organic compound. The complexing agent does not affect the electrochemical activity of the polysulfide ions and the dissolving deposition reaction of the metal lithium in the negative electrode; and meanwhile, generation of a secondary reaction between lithium polysulfide and a lithium sheet can be blocked, and the effect of the metal lithium can be protected.

Description

technical field [0001] The present invention relates generally to lithium-sulfur batteries, and more particularly to diffusion inhibition of polysulfide-containing ions within sulfur batteries. Background technique [0002] Lithium-sulfur batteries have been developed in the 1990s, but they have been silent for a while. Now, due to its incomparable high specific energy and other properties, it has received the attention of researchers again. Relevant research work at home and abroad has been quite active in recent years, and it is now at the critical stage of technological breakthroughs. Typical rechargeable batteries of this type include an anode with lithium metal as the active material, a lithium metal alloy as the active material, or a lithium metal / carbon composite as the active anode material. Such batteries include a cathode that contains sulfur as the active material. [0003] When charging a lithium-sulfur battery, lithium ions at the anode are reduced to lithium...

AI Technical Summary

Problems solved by technology

[0005] Despite the above advantages, lithium-sulfur batteries are still far from being practical. The current main problems include: (1) The lithium metal on the negative electrode reacts with the lithium polysulfide dissolved in the electrolyte, and the elemental sulfur on the positive electrode side gradually The generated lithium polysulfide enters the electrolyte, and then reacts with metal lithium, which eventually causes the loss of positive and negative active materials and the collapse of the region; (2) During the discharge process of the lithium-sulfur battery, the formed lithium polysulfide enters the electrolyte and is highly rich The accumulated polysulfide lithium causes the viscosity of the electrolyte to increase, resulting in a decrease in the conductivity of the electrolyte and a significant drop in battery performance; (3) The operating temperature of the lithium-sulfur battery system is as high as 300-400°C, which requires more expensive high-temperature-resistant materials and complex The preparation process to prevent the battery from burning

1) "Acta Electrochemical Society" (ElectrochimicaActa70, 2012, 344–348) reported the work of Sheng S. Zhang adding complexing agent lithium nitrate to the electrolyte. The addition of lithium nitrate can form a protective layer on the surface of the lithium negative electrode, but the The protective layer will be consumed gradually, and it will gradually fail after a dozen charge-discharge cycles

2) "Journal of Power Sources" (Journal of Power Sources 183, 2008, 441–445) introduced another method, that is, adding toluene, methyl acetate, etc. to the electrolyte to inhibit the dissolution of lithium polysulfide, but this method It is easy to cause a decrease in the conductivity of the electrolyte

The lithium-sulfur battery is characterized by a relatively large volume change, and the dissolution and deposition of lithium ions are not fixed, so this solid ceramic film is difficult to withstand the long-term operation of the battery.

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