Al2Ox-Coated Cathode Material for Solid-State Li-Ion Cycle Stability
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Solution Overview
Problem
Solid-state lithium-ion secondary batteries face challenges in maintaining consistent cycle characteristics due to oxidative decomposition of the solid electrolyte and increased internal resistance when the positive electrode active material is coated with an oxide, which inhibits lithium ion conduction.
Innovation Solution
A coated positive electrode active material is developed with a surface coating of Al2Ox (where 0<x<3), which reduces oxidative decomposition and conduction inhibition, thereby improving cycle characteristics by limiting the decomposition of the solid electrolyte and increasing lithium diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive electrode active material is coated with an oxide, then oxidative decomposition of the solid electrolyte is reduced, but lithium ion conduction is inhibited and internal resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material from conventional oxides to a specific compound containing Al, Li, and F elements with controlled atomic ratios. This parameter change allows the coating to simultaneously provide oxidative decomposition resistance and maintain lithium ion conduction, resolving the technical contradiction between protection and conductivity.
Solution Approach 2:
The patent uses a composite coating material comprising multiple elements (Al, Li, F) in specific ratios rather than a single oxide material. This composite approach enables the coating to exhibit both protective properties against oxidative decomposition and favorable ion conduction characteristics, overcoming the limitations of simple oxide coatings.
2Duration of action of stationary object
If the surface of the positive electrode active material is covered with a coating material, then cycle characteristics are improved, but lithium diffusion is reduced
Solution Approach 1:
The patent optimizes the atomic ratios of Al, Li, and F in the coating material to achieve a balance between cycle stability and lithium diffusion speed. By precisely controlling these compositional parameters, the coating provides sufficient protection for improved cycle characteristics while maintaining adequate lithium ion diffusion rates.
Solution Approach 2:
The coating material is designed with specific local compositional characteristics that facilitate lithium ion diffusion while providing oxidative protection. The presence of Li and F elements in controlled amounts creates local regions that are ion-conductive, resolving the contradiction between protection and diffusion.
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 coated positive electrode active material effectively enhances the cycle characteristics and charge-discharge capacity of batteries by reducing oxidative decomposition and internal resistance, leading to improved battery performance.
Implementation Method 1
oxidative decomposition of the solid electrolyte
Implementation Method 2
inhibits lithium ion conduction
Implementation Method 3
increasing lithium diffusion
Data Source
AI summary
A coated positive electrode active material includes a positive electrode active material and a coating material that covers at least a part of a surface of the positive electrode active material. The coating material includes Al2Ox where x satisfies 0<x<3. A positive electrode material includes the coated positive electrode active material and a first solid electrolyte material. The first solid electrolyte material includes Li, M, and X. M is at least one selected from the group consisting of metal elements and metalloid elements other than Li. X is at least one selected from the group consisting of F, Cl, Br, and I.