Transition Metal Precursor Tap Density Ratio for Battery Stability
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Solution Overview
Problem
During the manufacturing of lithium secondary batteries, the particles constituting the active material are broken or crushed in the slurry preparation and rolling processes, leading to unstable surfaces that react with the electrolyte, forming high-resistance films and causing performance deterioration at the negative electrode, electrolyte consumption, and gas generation.
Innovation Solution
A transition metal precursor with a specific ratio of tap density to average particle diameter D50, ranging from 500:1 to 3500:1, is used to prepare a lithium transition metal oxide, which is then mixed with a lithium precursor and sintered, resulting in a lithium composite transition metal oxide with a controlled average particle diameter ratio, minimizing particle breakage and enhancing electrode stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the average particle diameter of the precursor is increased to increase tap density, then the packing density of the electrode increases, but the particles are more prone to breakage and crushing during slurry preparation and rolling processes
Solution Approach 1:
The invention changes the physical and chemical parameters of the precursor particles by controlling the average particle diameter within a specific range (1-30 μm) and optimizing the tap density to average particle diameter ratio. This parameter optimization allows the particles to maintain sufficient strength during processing while achieving high packing density in the electrode, resolving the contradiction between particle size and particle strength
Solution Approach 2:
The invention performs preliminary stabilization treatment on the precursor particles before electrode manufacturing. The particles are stabilized through controlled sintering conditions and surface treatment, which strengthens the particle structure in advance. This preliminary strengthening prevents breakage during subsequent slurry preparation and rolling processes, allowing the use of larger particles for high tap density without compromising particle integrity
2Area of stationary object
If the specific surface area of the active material is increased, then the reaction surface area increases, but the liquid phase ratio increases causing hindered electric flow and requiring more binder and conductive material
Solution Approach 1:
The invention optimizes the particle size parameters to achieve a balanced specific surface area that provides sufficient reaction surface while minimizing excessive surface area. By controlling the average particle diameter and particle size distribution, the invention reduces the total surface area that would otherwise require excessive binder and conductive material, thereby maintaining good electric flow and electrode reliability
3Manufacturing precision
If the particles are broken or crushed during manufacturing processes, then the particle size decreases, but the unstable surfaces react with electrolyte forming high-resistance films and causing performance deterioration
Solution Approach 1:
The invention applies preliminary stabilization treatment to the precursor particles before electrode manufacturing. The particles are stabilized through controlled sintering and surface treatment processes that create a stable surface layer. This preliminary stabilization prevents the formation of unstable surfaces that would otherwise react with the electrolyte to form high-resistance films, thereby maintaining electrode stability and performance
Solution Approach 2:
The invention provides beforehand protection to the particle surfaces by forming stable surface layers and structures during the precursor preparation and stabilization phases. This protective layer acts as a cushion against the harmful effects of particle breakage, preventing direct contact between fresh particle surfaces and the electrolyte, thus avoiding the formation of high-resistance films and performance deterioration
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 reduces particle breakage and stabilizes the electrode, improving the lifespan and safety of lithium secondary batteries by maintaining a high tap density while controlling particle size changes during sintering and pulverization, thus enhancing high-temperature characteristics and output performance.
Implementation Method 1
drying, and sintering under specific conditions, thereby obtaining lithium transition metal oxide particles
Data Source
AI summary
Disclosed are a transition metal precursor for preparation of a lithium transition metal oxide, in which a ratio of tap density of the precursor to average particle diameter D50 of the precursor satisfies the condition represented by Equation 1 below, and a lithium transition metal oxide prepared using the same.0<Tap densityAverage particle diameter D50 of transition of metal precursor<3500 (g/cc·cm)(1)