Positive Electrode Active Material with Oxygen-Controlled Al Doping
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Solution Overview
Problem
Lithium nickel cobalt metal oxides used in lithium secondary batteries face limitations in high-temperature life characteristics and resistance due to poor thermal stability and surface defects caused by washing processes, which degrade battery performance.
Innovation Solution
A method involving sintering a mixture with 70 mol% nickel and a lithium-containing raw material, followed by secondary sintering with an aluminum-containing raw material in a controlled oxygen atmosphere, and subsequent heat treatment with a boron-containing raw material to form a coating layer, resulting in a positive electrode active material with improved high-temperature life and resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of nickel in lithium nickel cobalt metal oxide is increased to increase capacity, then the reversible capacity is improved, but thermal stability deteriorates and washing process becomes essential causing surface defects
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core contains high-nickel content (70-90 mol%) for high capacity, while the shell contains aluminum doping (0.01-0.2 mol%) for thermal stability. This spatial differentiation allows each region to have optimized properties for its specific function.
Solution Approach 2:
The patent uses composite materials by combining lithium nickel cobalt oxide with aluminum-containing compounds to form a composite structure. The aluminum-doped shell acts as a protective layer that maintains thermal stability while allowing the high-nickel core to provide high capacity.
2Quantity of substance
If washing process is performed to remove unreacted residual lithium, then purity is improved, but surface defects occur and life characteristics are degraded
Solution Approach 1:
The patent applies preliminary action by performing aluminum doping through sintering before the washing process. This pre-treatment creates a protective shell that prevents surface defects during subsequent washing, allowing thorough purification without damaging the surface.
Solution Approach 2:
The aluminum-doped shell serves as a cushioning layer that protects the underlying high-nickel material from surface defects during washing. This protective shell absorbs the mechanical and chemical stress of the washing process, preventing direct damage to the active material surface.
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 method enhances the high-temperature life and resistance characteristics of lithium secondary batteries by controlling the aluminum doping degree and forming a stable coating layer, leading to improved thermal stability and capacity retention.
Implementation Method 1
sintering a mixture of a positive electrode active material precursor containing 70 mol % or more of nickel (Ni), based on a total molar amount of metals in the precursor, and a lithium-containing raw material to prepare a pre-sintered product
Implementation Method 2
sintering a mixture of the pre-sintered product and an aluminum-containing raw material in an oxygen atmosphere containing 20 vol % to 100 vol % of oxygen
Implementation Method 3
sintering a mixture of the pre-sintered product and an aluminum-containing raw material in an oxygen atmosphere containing 20 vol % to 100 vol % of oxygen to prepare a lithium transition metal oxide
Implementation Method 4
heat treating the lithium transition metal oxide and a boron-containing raw material to form a coating layer on the lithium transition metal oxide
Data Source
AI summary
A positive electrode active material and a method of making the same, a positive electrode including the same, and a lithium secondary battery including the same are disclosed herein. In some embodiments, a method includes (A) sintering a mixture of a positive electrode active material precursor containing 70 mol % or more of nickel (Ni), based on a total amount of metals in the precursor, and a lithium-containing raw material to prepare a pre sintered product, (B) sintering a mixture of the pre-sintered product and an aluminum-containing raw material in an oxygen atmosphere containing 20 vol % to 100 vol % of oxygen to prepare a lithium transition metal oxide, wherein a concentration of oxygen is reduced according to sintering time, and (c) heat treating a mixture of the lithium transition metal oxide and a boron-containing raw material to form a coating layer on the lithium metal oxide.