Positive Electrode Active Material Sintering for Low Lithium Impurities
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Solution Overview
Problem
Lithium secondary batteries face limitations due to the presence of lithium impurities on the surface of nickel-rich positive electrode active materials, which can lead to gas generation, safety issues, and defects, and existing methods have not effectively controlled these impurities.
Innovation Solution
A method involving a two-stage sintering process with temperature holding sections between 400° C. to 650° C. and 700° C. to 900° C. is used to mix a lithium compound, a transition metal precursor, and a metal oxide additive, enhancing reactivity and stabilizing the lithium transition metal oxide structure to suppress lithium impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a nickel-rich active material system is used to achieve high capacity, then battery capacity is improved, but lithium impurities remain on the surface which vaporize during charge/discharge to generate gas and reduce safety
Solution Approach 1:
The patent applies preliminary action by conducting a two-stage sintering process before battery assembly to remove lithium impurities from the positive electrode active material surface. The first stage (400-650°C) removes carbonates and hydroxides, while the second stage (700-900°C) removes remaining lithium compounds, preventing gas generation during subsequent battery charge/discharge cycles
Solution Approach 2:
The patent applies parameter changes by optimizing the sintering temperature profile with two distinct stages. The first stage operates at 400-650°C to remove specific impurities (carbonates and hydroxides), while the second stage operates at 700-900°C to remove remaining lithium compounds. This staged parameter adjustment enables selective removal of different impurity types without damaging the active material structure
2Quantity of substance
If a nickel-rich active material system is used to achieve high capacity, then battery capacity is improved, but lithium impurities cause the composition to gelate and agglomerate, creating defects on the electrode surface
Solution Approach 1:
The patent applies preliminary action by removing lithium impurities through two-stage sintering before the coating process. This preliminary purification prevents the gelation and agglomeration that would otherwise occur during composition preparation, ensuring uniform coating and defect-free electrode surfaces
Solution Approach 2:
The patent applies parameter changes by controlling the sintering temperature in two stages to selectively remove lithium impurities without affecting the active material's capacity properties. The first stage (400-650°C) removes carbonates and hydroxides, while the second stage (700-900°C) removes remaining lithium compounds, maintaining both capacity and surface quality
3Ease of manufacture
If lithium compound and transition metal precursor are mixed to form positive electrode active material, then the material is formed, but lithium impurities remain on the surface due to insufficient reactivity
Solution Approach 1:
The patent applies parameter changes by implementing a two-stage sintering process with optimized temperature ranges. The first stage (400-650°C) promotes initial reaction and removes carbonates and hydroxides, while the second stage (700-900°C) completes the reaction and removes remaining lithium impurities, achieving both ease of manufacture and low impurity content
Solution Approach 2:
The patent applies preliminary action by using the first sintering stage to remove carbonates and hydroxides before the second stage removes remaining lithium compounds. This staged approach preliminarily reduces impurity content after material formation, maintaining ease of manufacture while reducing lithium impurity content
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 reactivity between the lithium compound and transition metal precursor, reduces lithium impurities, and stabilizes the lithium transition metal oxide structure, enhancing the performance and safety of lithium secondary batteries.
Implementation Method 1
sintering the mixture to form a lithium transition metal oxide
Implementation Method 2
the sintering is performed through two-stage temperature holding sections, a temperature of a first temperature holding section is in a range of 400° C. to 650° C., and a temperature of a second temperature holding section is in a range of 700° C. to 900° C.
Implementation Method 3
improves reactivity between a lithium compound and a transition metal precursor
Data Source
AI summary
Provided is a method of preparing a positive electrode active material, which includes preparing a mixture by mixing a lithium compound, a transition metal precursor, and a metal oxide additive, and sintering the mixture to form a lithium transition metal oxide, wherein the sintering is performed through two-stage temperature holding sections, a temperature of a first temperature holding section is in a range of 400° C. to 650° C., and a temperature of a second temperature holding section is in a range of 700° C. to 900° C. A positive electrode including a positive electrode active material prepared according to the method, and a lithium secondary battery including the positive electrode is also provided.