High-Nickel Cathode Material Cooling Profile for Moisture Control
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Solution Overview
Problem
Lithium nickel cobalt metal oxides for lithium secondary batteries face challenges with unstable structure and low thermal stability, leading to issues like decomposition and ignition during internal short circuits, and existing methods fail to effectively control moisture penetration during preparation, affecting capacity and resistance.
Innovation Solution
A method involving mixing a lithium raw material with a high nickel-containing transition metal hydroxide, sintering at 700°C to 900°C, and incorporating an aging step during cooling to minimize moisture penetration, resulting in a positive electrode active material with a stable structure and reduced moisture content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of nickel in lithium nickel cobalt metal oxide is increased to achieve high reversible capacity, then capacity is improved, but thermal stability deteriorates and the material becomes prone to decomposition and ignition
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high-nickel content (Ni≥0.80) for high capacity, while the outer shell contains lower-nickel content (Ni=0.60-0.79) for thermal stability. This spatial differentiation of composition allows simultaneous optimization of both capacity and safety properties.
Solution Approach 2:
The patent uses composite materials by combining two different lithium nickel cobalt oxide compositions into a single electrode structure. The core region uses LiNi0.80-0.85Co0.10-0.15Mn0.05-0.10O2 for high capacity, while the shell region uses LiNi0.60-0.79Co0.10-0.15Mn0.05-0.10O2 for stability, creating a composite electrode that achieves both high capacity and thermal stability.
2Ease of manufacture
If conventional one-step sintering process is used for preparing lithium nickel cobalt metal oxide, then manufacturing process is simple, but reaction between precursor and lithium source is not smooth and unstable structure is formed
Solution Approach 1:
The patent segments the sintering process into two distinct stages: first sintering the precursor with lithium source at 600-700°C for 5-10 hours to ensure complete reaction, then performing a second sintering at 700-900°C for 5-10 hours to optimize the final structure. This two-step approach ensures both complete reaction and structural stability.
Solution Approach 2:
The patent applies preliminary action by performing the first sintering step to completely react the precursor with lithium source before conducting the second sintering step. This preliminary reaction ensures that all precursor material is converted to the desired phase, preventing unstable structures and improving overall manufacturing precision.
3Ease of manufacture
If cooling process is performed without moisture control, then manufacturing process is simple, but moisture penetrates into the material causing increased resistance
Solution Approach 1:
The patent uses an inert atmosphere (nitrogen or argon gas) during the cooling process to prevent moisture penetration into the lithium nickel cobalt metal oxide. The inert gas environment excludes oxygen and moisture, preventing oxidation and resistance increase while maintaining relatively simple manufacturing conditions.
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 approach enhances the stability and performance of the positive electrode active material, improving capacity and resistance characteristics, thereby increasing the reliability and efficiency of lithium secondary batteries.
Implementation Method 1
sintering the mixture to prepare a positive electrode active material, wherein the sintering includes a sintering step of heat-treating at 700°C to 900°C for 8 hours to 12 hours
Implementation Method 2
an aging step of having a holding time when a temperature reaches a specific point during the cooling step
Data Source
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AI summary
The present invention relates to a method of preparing a positive electrode active material, which includes mixing a lithium raw material with a high nickel-containing transition metal hydroxide containing nickel in an amount of 60 mol% or more based on a total number of moles of the transition metal hydroxide and sintering the mixture to prepare a positive electrode active material, wherein the sintering includes a sintering step of heat-treating at 700°C to 900°C for 8 hours to 12 hours, a cooling step of cooling to room temperature, and an aging step of having a holding time when a temperature reaches a specific point during the cooling step, a positive electrode active material which is prepared by the method and has a reduced moisture content, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material.