Positive electrode and high-safety and high-cyclicity lithium metal solid-state battery

Abstract

The invention discloses a positive electrode and a lithium metal solid-state battery with high safety and high cyclicity, and belongs to the field of lithium metal solid-state batteries, the positive electrode of the lithium metal solid-state battery comprises an active substance, the bond energy of elements and oxygen in the active substance is greater than 390 kJ / mol, and the decomposition temperature of the active substance is greater than 250 DEG C. The proper active substance is screened out through the bond energy of the chemical bond and the decomposition temperature to serve as the positive electrode of the lithium metal solid-state battery, the active substance with large binding energy of elements and oxygen is selected, and the oxygen evolution reaction of the active substance in the charging process can be effectively reduced, so that the spontaneous combustion possibility of the lithium metal solid-state battery is reduced; the safety of the lithium metal solid-state battery is greatly improved; meanwhile, the selection of the active substance needs to meet the charging cut-off voltage for stabilizing the electrolyte, and the cycling stability of the battery is ensured.

Description

technical field [0001] The invention relates to the field of batteries, in particular to a positive electrode and a lithium metal solid-state battery with high safety and high cycle performance. Background technique [0002] Lithium metal solid-state batteries are widely used in the field of electronic products as renewable clean energy storage devices, which can meet the stringent requirements of emerging industries such as new energy vehicles, and are one of the most promising next-generation high-energy density storage devices. [0003] However, the safety issues and poor cycling performance of lithium metal solid-state batteries have always limited its practical use. After long-term research by the applicant of this patent, it was accidentally found that in the lithium metal solid-state battery, at the end of charging, the deposition of lithium on the negative electrode is about to end, and micron and nanoscale whiskers or small crystal grains will be formed on the initi...

AI Technical Summary

Problems solved by technology

Because of their short life and high reactivity, after migrating to the side of the metal lithium negative electrode, chain reactions with the tiny particles of metal lithium are very easy to occur. After the heat is released, the metal lithium melts at 180 ° C, which will make the lithium metal solid-state battery further Short circuit, and a series of chain reactions will eventually cause the battery to spontaneously ignite

In addition, if the thermal decomposition temperature of the positive electrode material in the fully charged state is too low, lower than 250°C, the lithium metal has gradually liquefied and gasified, and the combination of the liquefied lithium metal and the rapidly exothermic positive electrode material will further aggravate the thermal runaway of the battery cell. , detrimental to safety performance

[0004] In addition, some scholars proposed to use liquid electrolyte and diaphragm to assemble lithium metal solid-state battery, such as patent CN111916815A. However, during the charging process of lithium battery, the internal temperature rises, which will cause the electrolyte to decompose and generate a lot of heat, which will lead to The battery temperature rises further

In addition, after a lithium battery has been charged and discharged many times, the lithium negative electrode will produce lithium dendrites, which can easily pierce the diaphragm, resulting in short circuit, leakage or even explosion of the battery.

[0005] There are also some scholars who have proposed to use solid electrolyte membranes instead of ordinary diaphragms and electrolytes, such as CN209447927U. However, the long-term research of the applicant of this patent has found that when the voltage is above 4.2V, PEO, sulfide electrolytes, and some surface modifiers are all Unstable at the beginning, it will decompose and produce gas, which will also cause the temperature to rise, which will affect the cycle stability of the battery

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