Lithium Reduction Resistant Layer Composition for Solid Electrolyte Interface
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Solution Overview
Problem
The existing lithium reduction resistant layers in all-solid-state lithium secondary batteries exhibit poor Li ion conductivity at the interface with the solid electrolyte layer, despite having excellent conductivity within the layer, due to point-contact interactions between particles, leading to potential short circuits and dendrite growth.
Innovation Solution
A composition comprising a solvent, lithium compound, lanthanum compound, zirconium compound, and a metal compound (M) is used to form a lithium reduction resistant layer with a specific stoichiometric ratio, which is then processed into a cubic garnet-type crystal structure through a multistage heating treatment, ensuring excellent Li ion conductivity and reduction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a lithium reduction resistant layer is formed by solid phase reaction with particle mixing, then the layer can be manufactured with simple process, but the Li ion conductivity at the interface between layers deteriorates due to point-contact between particles
Solution Approach 1:
The invention changes the physical state parameter of the starting materials from solid particles to soluble compounds in liquid form. By dissolving lithium compound, lanthanum compound, zirconium compound, and metal compound M in a solvent to form a homogeneous liquid composition, the invention eliminates the point-contact issue between solid particles. After coating and heating treatment, this liquid-based approach produces a lithium reduction resistant layer with continuous structure and excellent Li ion conductivity at the interface, while maintaining manufacturing simplicity through solution processing.
2Stability of the object's composition
If lithium compound is added in excess (4-20 atom %) to compensate for Li loss during high temperature sintering, then the final composition achieves stoichiometric balance, but the manufacturing process complexity increases due to multiple addition steps and precise control requirements
Solution Approach 1:
The invention performs preliminary action by pre-calculating and incorporating the exact stoichiometric amount of lithium compound into the liquid composition before coating. Unlike the conventional approach that adds lithium after sintering to compensate for losses, this method formulates the liquid precursor with the precise final composition required. The heating treatment then directly converts the liquid composition to the target lithium reduction resistant layer without needing subsequent lithium addition steps, thereby simplifying the manufacturing process while ensuring compositional accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting lithium reduction resistant layer demonstrates enhanced Li ion conductivity and reduction resistance, improving the overall performance and safety of the lithium secondary battery by preventing short circuits and dendrite growth.
Implementation Method 1
a lithium compound, a lanthanum compound, a zirconium compound, and a compound containing a metal M, each showing solubility in the solvent
Implementation Method 2
processed into a cubic garnet-type crystal structure through a multistage heating treatment
Implementation Method 3
the obtained mixture is temporarily fired. Then, in order to compensate a loss of Li in the final sintering which is a post-process, an Li compound is added
Data Source
AI summary
A composition for forming a lithium reduction resistant layer includes a solvent, and a lithium compound, a lanthanum compound, a zirconium compound, and a compound containing a metal M, each of which shows solubility in the solvent, and in which with respect to the stoichiometric composition of a compound represented by the general formula (I), the lithium compound is contained in an amount 1.05 times or more and 2.50 times or less, the lanthanum compound and the zirconium compound are contained in an amount 0.70 times or more and 1.00 times or less, and the compound containing a metal M is contained in an equal amount.Li7-xLa3(Zr2-x,Mx)O12 (I)