Oxygen-Deficient Cathode Material for Battery Stability
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Solution Overview
Problem
Lithium secondary batteries using traditional cathode active materials like LiCoO2 face reduced service life, structural instability, and risk of explosion due to repeated charge/discharge cycles, with inadequate electrochemical properties and stability, necessitating the development of improved cathode active materials with enhanced lithium diffusion, reduced interfacial resistance, and improved charge/discharge performance.
Innovation Solution
A method involving the heat-treatment of a first metal oxide in a nitrogen-containing gas atmosphere to form a second metal oxide with a lower oxygen ratio, followed by firing with lithium salt to create a lithium metal oxide with a core-shell structure and pore formation, enhancing lithium diffusion and content within the cathode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional cathode active materials like LiCoO2 are used, then high energy density and operating voltage are achieved, but service life is rapidly reduced and structural instability occurs due to repeated charge/discharge
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen ratio of the metal oxide precursor during heat treatment. By adjusting the oxygen ratio to be lower than stoichiometric (creating oxygen deficiency), the crystal structure and electrochemical properties are modified, resulting in improved service life and stability while maintaining high energy density in the final lithium metal oxide cathode material.
2Power
If traditional cathode active materials like LiCoO2 are used, then high operating voltage is achieved, but structural instability and risk of explosion occur due to repeated charge/discharge
Solution Approach 1:
The patent modifies the oxygen ratio parameter of the metal oxide precursor to create a controlled oxygen-deficient structure. This parameter change stabilizes the crystal structure during charge/discharge cycles, preventing structural collapse and reducing the risk of explosion, while maintaining the high operating voltage characteristics necessary for battery performance.
3Stability of the object's composition
If metal oxide with high oxygen ratio is used, then complete oxidation is achieved, but lithium diffusion coefficient is low and interfacial resistance is high
Solution Approach 1:
The patent deliberately changes the oxygen ratio parameter to be lower than the stoichiometric value, creating an oxygen-deficient metal oxide precursor. This parameter modification reduces interfacial resistance and increases the lithium diffusion coefficient, thereby improving electrochemical performance while maintaining appropriate oxidation state for the final cathode material.
Solution Approach 2:
The oxygen-deficient structure created by controlling the oxygen ratio generates a porous or defective crystal structure with increased surface area and reduced diffusion pathways. This porous characteristic facilitates faster lithium ion diffusion and reduces interfacial resistance, improving overall electrochemical performance.
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
This approach improves the charge/discharge properties and lifespan of lithium secondary batteries by facilitating easier lithium diffusion and increasing lithium content, resulting in improved electrochemical performance and stability.
Implementation Method 1
preparing a second metal oxide having an oxygen ratio lower than that of the first metal oxide by heat-treating the first metal oxide in a nitrogen-containing gas atmosphere
Implementation Method 2
preparing a lithium metal oxide by firing the second metal oxide and lithium salt
Data Source
AI summary
A method for preparing a cathode active material is provided. The method for preparing a cathode active material can comprise the steps of: preparing a first metal oxide; preparing a second metal oxide having an oxygen ratio lower than that of the first metal oxide by heat treating the first metal oxide in a nitrogen-containing gas atmosphere; and preparing a lithium metal oxide by firing the second metal oxide and a lithium salt.