Positive Electrode Particle Orientation for High-Voltage Cycling
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Solution Overview
Problem
Existing positive electrodes in secondary batteries, particularly lithium-ion batteries, face challenges in maintaining high-voltage cycling performance due to issues like pulverization and phase changes caused by uneven distribution and orientation of lithium transition metal composite oxides on the current collector.
Innovation Solution
A positive electrode is designed with a controlled morphology and orientation of lithium transition metal composite oxides, where the average particle sizes in parallel and perpendicular directions to the current collector plane are within specific ratios, ensuring proper distribution and maintaining active and inactive crystal plane proportions, thereby enhancing stability and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium transition metal composite oxide particles are used in positive electrode, then capacity and electrochemical performance are improved, but particle pulverization and phase changes occur during cycling
Solution Approach 1:
The patent changes the particle morphology parameters of lithium transition metal composite oxide, specifically controlling the aspect ratio (Dp/Dv) to be between 1.1 and 2.3. This parameter optimization reduces internal stress during lithium insertion/extraction cycles, preventing particle pulverization and phase changes while maintaining high capacity and cycling performance
Solution Approach 2:
The patent introduces orientation control as a new dimension of particle arrangement on the current collector surface. By controlling the orientation of particles, the patent distributes stress more evenly during cycling, preventing the pulverization and phase changes that occur with random orientation, thereby improving both particle stability and cycling performance
2Quantity of substance
If particle size of lithium transition metal composite oxide is increased, then capacity is improved, but particle pulverization occurs during charge-discharge cycles
Solution Approach 1:
The patent optimizes the particle size parameters by controlling the average particle size in the plane direction (Dp) to be between 5-25 μm and the aspect ratio (Dp/Dv) to be between 1.1 and 2.3. This parameter optimization allows particles to maintain larger size for high capacity while the controlled aspect ratio prevents internal stress concentration, avoiding pulverization during cycling
3Reliability
If conventional positive electrode structure is used, then manufacturing is simple, but high-voltage cycling performance deteriorates due to uneven particle distribution
Solution Approach 1:
The patent adds orientation control as a new dimension to particle arrangement on the current collector surface. By controlling both the position and orientation of particles, the patent achieves uniform distribution that prevents localized stress concentration during high-voltage cycling, improving cycling performance without requiring complex manufacturing processes
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 results in improved high-voltage cycling performance and stability by preventing pulverization and maintaining crystallinity, as evidenced by minimal peak shifts and broadening in X-ray diffraction spectra after multiple charge-discharge cycles.
Implementation Method 1
the capacity of intercalation and deintercalation of lithium ions of the lithium transition metal composite oxide
Implementation Method 2
an X-ray diffraction spectrum at least has a characteristic peak P1 and a characteristic peak P2 in a range of 17° to 20°
Data Source
AI summary
A positive electrode, including a current collector and a positive electrode active material layer provided on the current collector, the positive electrode active material layer including a lithium transition metal composite oxide, where in a direction parallel to a plane on which the current collector is located, an average particle size of the lithium transition metal composite oxide is Dp, and in a direction perpendicular to the plane on which the current collector is located, an average particle size of the lithium transition metal composite oxide is Dv, satisfying:1.1≤Dp/Dv≤2.3.