Preparation method of lithium yttrium halide and application thereof in solid electrolyte and battery

Abstract

The invention provides a preparation method of lithium yttrium halide and application thereof in a solid electrolyte and a battery. The preparation method of the lithium yttrium halide comprises the following steps: (1) supplying yttrium halide salt and lithium salt to a ball mill tank for mechanical synthesis; (2) annealing a mechanically synthesized product under the protection of inert gas to obtain the lithium yttrium halide with a chemical formula of Li3YAxB6-x, wherein A is Cl<-> and/or Br<->, and B is selected from at least one of I<->, F<->, BF<4->, PF<6->, BOB<->, TFSI<-> and FSI<->;x is more than 0 and less than or equal to 6. The method can be carried out under normal pressure, and the raw materials are low in cost; the prepared Li3YCl6 is high in thermal stability and high incrystallinity, and has relatively high electrical conductivity at normal temperature.

Description

technical field [0001] The invention relates to the technical field of solid-state batteries, in particular to a preparation method of yttrium-lithium halide and its application in solid-state electrolytes and batteries. Background technique [0002] Since Sony's lithium-ion battery was launched in 1991, it has been widely used in electronic products, and in recent years has been used for mobility and transportation. The energy density of existing lithium-ion batteries can be as high as 265Wh / Kg, and the number of charge-discharge cycles at an operating temperature of -20 to 40°C and a continuous charging time of 1.5h is usually between 2000 and 4000 times. The cell consists of a graphite-based anode and a Ni / Co-containing cathode separated by an insulating polymer separator. Lithium ions shuttle back and forth into the anode during charging and into the cathode during discharge. To ensure efficient transport of lithium ions between the electrodes, the anode, separator, and...

AI Technical Summary

Problems solved by technology

[0004] At present, polymer electrolytes have been successfully commercialized in electric vehicles, and the density of polymer electrolytes is about 1.7 g / cm 3 , most are amorphous and soft, which facilitates casting of thin films (200MPa) , the density of the LPS electrolyte is ~2.2 g / cm 3 , and have higher conductivity than polymer electrolytes at room temperature

However, the raw material cost of LPS is high and expensive, and it cannot be well connected with lithium metal anodes or 3.5V / 4V level cathodes, and it is also necessary to form a coating on the active surface of the cathode to reduce the reaction between the LPS electrolyte and the cathode material. High voltage is required to lower the grain boundary resistance when assembling the battery, and battery assembly needs to be done in an expensive dry room to avoid the reaction of LPS with moisture in the air, which not only makes the battery assembly more complicated, but also reduces the energy density of the battery ; solid electrolyte LLZO based on oxygen and composed of crystalline phases of lithium, lanthanum, zirconium and oxygen Unlike LPS, this material is stable for lithium metal anodes, but it is difficult to obtain a good interface

Recent research results show that LLZO is not thermodynamically stable in 4V-level cathodes, has a high hardness and a higher density of about 4.5g / cm 3 Even higher, its interfacial impedance has a greater influence on the diffusion mobility of lithium ions, and it is also necessary to obtain a conductivity similar to that of a liquid electrolyte (at room temperature about 0.2mS / cm), these parameters make battery assembly more difficult

[0005] In summary, in practical battery applications, inorganic electrolytes may be more conductive than polymer electrolytes at room temperature, but have a higher crystallinity for the diffusion and migration of lithium ions due to their high density and hardness properties. Boundary resistance and high pressure (>200MPa) or high annealing temperature (>700°C) (due to the high temperature reaction with the cathode powder), increasing the difficulty of forming a complete battery with their electrode composition

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