Alkali metal-sulfur secondary battery containing a polymer-encapsulated sulfur cathode and manufacturing method

Abstract

Provided is a rechargeable alkali metal-sulfur cell comprising an anode active material layer, an electrolyte, and a cathode active material layer containing multiple particulates of a sulfur-containing material selected from a sulfur-carbon hybrid, sulfur-graphite hybrid, sulfur-graphene hybrid, conducting polymer-sulfur hybrid, metal sulfide, sulfur compound, or a combination thereof and whereinat least one of the particulates is composed of one or a plurality of sulfur-containing material particles being embraced or encapsulated by a thin layer of a high-elasticity ultra-high molecular weight polymer having a recoverable tensile strain no less than 2%, a lithium ion conductivity no less than 10-6 S / cm at room temperature, and a thickness from 0.5 nm to 10 [mu]m. This battery exhibits an excellent combination of high sulfur content, high sulfur utilization efficiency, high energy density, and long cycle life.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Patent Application No. 15 / 483,347, filed April 10, 2017, which is incorporated herein by reference. technical field [0003] The present invention provides a unique cathode composition and structure in secondary or rechargeable alkali metal-sulfur batteries, including lithium-sulfur batteries, sodium-sulfur batteries, and potassium-sulfur batteries. Background technique [0004] Rechargeable lithium-ion (Li-ion) and lithium metal batteries (including Li-sulfur and Li metal-air batteries) are considered to be used in electric vehicles (EV), hybrid electric vehicles (HEV) and portable electronic devices such as laptop Promising power sources for top-end computers and cell phones. With any other metal or metal intercalation compound as an anode active material (except Li with a specific capacity of 4,200mAh / g 4.4 Lithium, which is a metal element, has the highest capacity (3,861 mA...

AI Technical Summary

Problems solved by technology

During cycling, lithium polysulfide anions can migrate through the separator to the Li negative electrode, so they are reduced to solid precipitates (Li 2 S 2 and / or Li 2 S), resulting in a loss of active mass

In addition, the solid products precipitated on the surface of the positive electrode during discharge become electrochemically irreversible, which also contributes to the active mass loss

[0013] (4) More generally, significant disadvantages of cells containing cathodes comprising elemental sulfur, organosulfur, and carbon-sulfur materials involve soluble sulfide, polysulfide, organosulfide, carbon-sulfide, and / or carbon-sulfur Dissolution of polysulfides (hereafter referred to as anion reduction products) and excessive outward diffusion from the cathode into the rest of the cell

This process leads to several problems: high self-discharge rate, loss of cathode capacity, corrosion of current collectors and electrical leads leading to loss of electrical contact with active cell components, fouling of the anode surface leading to anode failure, and loss of electrical contact in the cell membrane diaphragm. Clogging of pores (resulting in loss of ion transport and large increase in internal resistance in the cell)

[0025] A specific object of the present invention is to provide a rechargeable alkali metal-sulfur cell based on rational materials and cell design, which overcomes or significantly reduces the The following problems: (a) dendrite formation (internal short circuit); (b) the very low electrical and ionic conductivity of sulfur, requires a large proportion (typically 30%-55%) of inactive conductive fillers and has significant proportion of inaccessible or inaccessible sulfur or alkali metal polysulfides); (c) dissolution of S and alkali metal polysulfides in the electrolyte; (d) migration of alkali metal sulfides from the cathode to the anode (which react irreversibly with Li, Na, or K), leading to active material loss and capacity fading (shuttle effect); and (e) short cycle life

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