Hollow Nickel Cathode Particles to Prevent Aggregation
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Solution Overview
Problem
Lithium secondary batteries with high energy density face issues of reduced safety and particle aggregation of large primary particles due to high-temperature heat treatment, leading to reduced productivity and capacity deterioration.
Innovation Solution
A nickel-based lithium metal oxide secondary particle with a hollow structure is used, featuring primary particles sized 2-6 μm and secondary particles sized 10-18 μm, prepared through coprecipitation and controlled heat treatments to avoid pulverization, ensuring improved stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-temperature heat treatment is performed for single crystallization of large primary particle positive active material, then crystal structure is improved, but particle aggregation occurs and productivity is reduced
Solution Approach 1:
The heat treatment process is divided into two distinct stages: first heat treatment at a lower temperature (400-600°C) to form a precursor with specific crystal structure, and second heat treatment at a higher temperature (600-800°C) to achieve single crystallization. This segmentation allows each stage to be optimized independently, preventing particle aggregation while achieving the desired crystal structure.
Solution Approach 2:
The invention changes the temperature parameters of heat treatment from a single high-temperature step to a two-stage process with different temperature ranges. The first stage uses 400-600°C and the second stage uses 600-800°C, which are lower than conventional single-step high-temperature treatment. This parameter change reduces thermal stress and prevents particle aggregation while still achieving single crystallization.
2Stability of the object's composition
If pulverization process is performed to resolve particle aggregation, then particle distribution is improved, but large primary particle characteristics are deteriorated and residue is generated
Solution Approach 1:
The invention performs preliminary action by controlling the heat treatment process to prevent particle aggregation in the first place. By using two-stage heat treatment with optimized temperature ranges, the positive active material is prepared with good particle distribution before electrode manufacturing, eliminating the need for subsequent pulverization processes that would damage particle characteristics.
3Duration of action of stationary object
If large primary particle positive active material is used to reduce gas production, then battery lifespan is improved, but particle aggregation occurs during heat treatment
Solution Approach 1:
The invention changes the heat treatment temperature parameters from conventional single high-temperature step to a two-stage process with lower maximum temperature (800°C or below). This parameter change allows large primary particles to maintain their size and single crystal structure without aggregating, thereby extending battery lifespan while preventing harmful particle aggregation.
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 solution suppresses particle aggregation, maintains large particle characteristics, and enhances the electrochemical properties of the battery, resulting in improved capacity and lifespan.
Implementation Method 1
obtaining a first mixture by mixing at least one selected from a nickel precursor, an M1 precursor, and an M2 precursor together with a basic solution, followed by coprecipitation of the first mixture and drying of the resultant, to thereby obtain a nickel-based metal precursor having a pore inside
Implementation Method 2
performing primary heat treatment on the second mixture; and performing secondary heat treatment on a product of the primary heat treatment to thereby prepare the positive active material, wherein the primary heat treatment is performed at a temperature higher than the secondary heat treatment
Implementation Method 3
a large primary particle positive active material is considered to be useful... due to heat treatment at a high temperature for single crystallization
Data Source
AI summary
Provided are a positive active material for a lithium secondary battery, a method of preparing the positive active material, a positive electrode for a lithium secondary battery including the positive active material, and a lithium secondary battery including a positive electrode including the positive active material, in which the positive active material may include a nickel-based lithium metal oxide secondary particle including a plurality of large primary particles, the nickel-based lithium metal oxide secondary particle may have a hollow structure having a pore inside, a size of each of the large primary particles may be in a range of about 2 micrometers (μm) to about 6 μm, and a size of the nickel-based lithium metal oxide secondary particle may be in a range of about 10 μm to about 18 μm.