Gel polymer binder for lithium sulfur battery electrode material and preparation method thereof

Abstract

The invention discloses a gel polymer binder for a lithium sulfur battery electrode material and a preparation method thereof. The preparation method comprises the following steps: (1) weighing 1,3-dichloro-2-propanol and polyethylene glycol, uniformly mixing, introducing N2 to deoxygenize, adjusting temperature, keeping constant temperature, adding a catalyst to accelerate a polymerization reaction, extracting a target product 1,3-dichloro-2-propyl alcohol polyethylene glycol ether, and then adjusting the pH value of the solution with an alkaline solution; (2) weighing a sulfosalt, completely dissolving the sulfosalt in distilled water, adjusting temperature, keeping constant temperature, and adding elemental sulfur to prepare a polysulfide salt; (3) mixing a product 1,3-dichloro-2-propyl alcohol polyethylene glycol ether in the step (1) and a product polysulfide salt in the step (2), adjusting temperature, keeping constant temperature, taking out a gel-like substance, and rotatably evaporating at a certain temperature to obtain a gel polymer binder for a lithium sulfur battery. The gel polymer binder prepared by the invention has the characteristics of easiness in operation, good bonding effect, high electrode active material utilization rate, good battery rate capability and the like.

Description

technical field [0001] The invention relates to a gel polymer binder for lithium-sulfur battery electrode materials and a preparation method thereof, belonging to the field of preparation of lithium-sulfur battery electrode materials. Background technique [0002] S 8 The theoretical specific capacity of the Li / S battery is 1672 mAh / g, the theoretical discharge voltage of the Li / S battery is 2.287 V, and the theoretical energy density is 3823.9 Wh / kg. Comparing the energy density and relative price of various materials in the secondary battery, elemental sulfur is At present, the positive electrode material with the highest energy density, compared with the mainstream lithium-ion battery on the market, the lithium-sulfur battery has a theoretical specific capacity 2 to 5 times of the former, so the lithium-sulfur battery has a good application prospect; lithium-ion battery and lithium-sulfur battery The positive electrode materials of the battery are all powdery substances,...

AI Technical Summary

Problems solved by technology

[0003] At present, the oily binder used in lithium-sulfur batteries is mainly polyvinylidene fluoride (PVDF) N-methylpyrrolidone solution, which is harmful to the environment Pollution is harmful to the health of operators, and it is expensive and non-conductive; in recent years, the research of water-based adhesives has also made some progress. Compared with oil-based adhesives, it is more environmentally friendly and the cost is lower. It will be lower, but its cycle performance and low temperature performance are not as good as oily binders, and it is slightly lacking in practicability. In addition, due to the limitation of coating methods, the sulfur loading per unit area in sulfur electrodes is often kept at 10mg / cm Below 2, thicker electrode sheets require a higher proportion of binder, which will lead to a decrease in the proportion of sulfur active materials in the electrode; at the same time, the binder is not conductive, which will lead to poor In addition, in the process of charging and discharging, the repeated dissolution and deposition of lithium metal is easy to form lithium dendrites, which are easy to fall off from the plate, resulting in a decrease in battery capacity; if lithium dendrites grow gradually, it will stimulate Extending through the diaphragm to the positive electrode leads to internal short circuit, causing unsafe factors such as fire or explosion; at the same time, its activity is too strong, causing the interface between it and the electrolyte to be unstable

[0004] In the prior art, PS (DCP-PEG) is used as a general gel type solid electrolyte, 1,3-dichloro-2-propanol poly Ethylene glycol ether-based sulfide PS (DCP-PEG) and lithium perchlorate were dissolved in tetrahydrofuran at a molar ratio of 8:1, and poured into a polytetrafluoroethylene mold to make a composite polymer electrolyte membrane, and PS (DCP-PEG) was characterized, and the ionic conductivity of the composite polymer electrolyte membrane was tested. The composite electrolyte membrane has not been actually prepared into a battery, and the electrochemical performance test has not been carried out.

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