Asymmetric semi-solid electrolyte, preparation method and metal lithium secondary battery

Abstract

The invention provides an asymmetric semi-solid electrolyte, a preparation method and a metal lithium secondary battery. By coating different solid electrolyte components on both sides of the separator, the electrolyte membrane on the side facing the positive electrode is composed of lithium salt, a polymer matrix that can conduct lithium ions, and inorganic ceramic powder. The electrolyte membrane on the side facing the negative electrode is A gel electrolyte formed of a polymer and a pore-forming agent. Such an asymmetric design, compared with the traditional pure asymmetric all-solid-state electrolyte system, not only solves the problem that the solid electrolyte needs to withstand high voltage on the positive side, but also regulates the deposition and growth of lithium on the negative side, avoiding the The generation of dendrites accelerates the reaction kinetics, which can be effectively applied in high energy density metal lithium secondary battery systems, greatly improving its cycle life.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to an asymmetric semi-solid electrolyte, a preparation method and a metal lithium secondary battery using the semi-solid electrolyte. Background technique [0002] As one of the most important energy storage and conversion devices, lithium-ion batteries use reversible chemical reactions to construct recyclable energy supply modules, which are the most practical means of energy conversion. It has been widely used in smartphones, notebook computers, electric vehicles, 3C digital products, wearable equipment, and large-scale energy storage power stations. However, existing lithium-ion batteries based on graphite as the negative electrode and lithium-containing transition metal oxides as the positive electrode are difficult to meet the growing demand for consumer electronics. At the same time, the safety factor of the liquid electrolyte used is low, and it cannot be assem...

AI Technical Summary

Problems solved by technology

[0003] However, due to the very high chemical and electrochemical reactivity of metallic lithium, the problem of dendrites still exists when metallic lithium is used as the negative electrode in solid-state batteries.

If we consider the problem from the positive electrode side; although the traditional inorganic solid-state electrolyte has high mechanical strength and high ion transmission rate, its preparation is complicated and the cost is very high. At the same time, the contact between it and the positive electrode material is very poor, which will lead to interface The impedance is very high, which makes it difficult to apply in commercial practical batteries

The organic polyethylene oxide-based polymer solid electrolyte has a low voltage window, which is difficult to apply to high-voltage lithium cobaltate, ternary and other positive electrode materials

If we consider the problem from the negative electrode side, if we use the traditional inorganic solid-state electrolyte; although it can suppress the puncture of lithium dendrites and improve safety by virtue of its high mechanical strength, its preparation is complicated and costly. The contact between them is very poor, which makes the interfacial impedance increase, which is difficult to apply in actual batteries, especially in actual batteries under high rate cycles

If the traditional organic polyoxyethylene solid electrolyte is used, although its cost is low and the interface contact is good, its lithium ion transmission rate is small and its mechanical strength is low, it is difficult to inhibit the puncture of lithium dendrites and the application of charge and discharge at high rates in process

The most important thing is: none of the above methods fundamentally change the deposition behavior of lithium, the growth behavior of lithium is still dendritic growth, there will still be a decrease in Coulombic efficiency caused by uneven deposition of lithium, short circuits in the battery, etc. behavior, in other words, lithium safety issues have not been fundamentally addressed

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