High-Nickel Cathode Precursor Morphology for Better Cycle Stability
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Solution Overview
Problem
High-nickel positive electrode materials in lithium-ion batteries suffer from poor cycling performance due to phase transitions during charging and discharging, leading to structural degradation and fragmentation, which is exacerbated by irregular primary particle shapes and sizes, resulting in inferior electrochemical properties.
Innovation Solution
A lithium-ion battery positive electrode material precursor composed of primary particles with neatly stacked single-sheet layers, each with flat edges, controlled within specific size and shape ranges, and limited fracture counts, is produced through a method involving precise pH and ammonia concentration control during synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel positive electrode materials are used to increase capacity and reduce cost, then energy density and cost performance are improved, but cycling performance deteriorates due to phase transitions and structural degradation
Solution Approach 1:
The patent changes the morphological parameters of primary particles by controlling synthesis conditions (pH value, adding agents) to achieve a specific length-to-width ratio range (1.5-3.0). This parameter optimization reduces anisotropic stress during phase transitions, allowing high nickel content (improving capacity) while maintaining structural stability for good cycling performance.
Solution Approach 2:
The patent creates local quality differences by ensuring uniform distribution of metal elements within primary particles and controlling the internal structure of single-sheet layers. This local uniformity prevents localized stress concentration during charging-discharging cycles, reducing crack propagation while maintaining high overall nickel content for energy density.
2Ease of manufacture
If primary particles have irregular shapes and sizes to simplify manufacturing, then manufacturing complexity is reduced, but electrochemical performance deteriorates due to poor regularity and broad size distribution
Solution Approach 1:
The patent identifies and controls key synthesis parameters (pH value range, adding agent concentration, temperature) to transform the manufacturing process from producing irregular particles to systematically generating particles with controlled morphology. The length-to-width ratio is maintained within 1.5-3.0 through these parameter optimizations, achieving both manufacturing feasibility and particle regularity.
Solution Approach 2:
The patent replaces mechanical grinding or physical size-control methods with a chemical synthesis approach where particle morphology is controlled during formation through solution chemistry (pH control, complexing agents). This substitution allows precise morphological control without complex mechanical processing steps.
3Use of energy by moving object
If phase transitions occur during charging and discharging, then electrochemical activity is enhanced, but anisotropic stress increases leading to crack propagation and structural collapse
Solution Approach 1:
The patent changes the geometric parameters of primary particles (length-to-width ratio controlled at 1.5-3.0) to modify stress distribution patterns during phase transitions. This morphological optimization allows phase transitions to proceed with reduced anisotropic stress concentration, preventing crack initiation while maintaining electrochemical activity.
Solution Approach 2:
The patent creates a more robust particle structure beforehand through controlled synthesis, where the optimized morphology and uniform element distribution serve as a cushion against stress during subsequent phase transitions. This pre-engineered structure prevents crack propagation that would otherwise occur during normal charging-discharging cycling.
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 precursor ensures high regularity and integrity of primary particles, reducing side reactions and structural damage during cycling, thereby enhancing capacity retention and cycle performance.
Implementation Method 1
controlling a pH value to be 9.8-11.3, an ammonia concentration to be 2g/L-12g/L
Implementation Method 2
introducing a raw material including a nickel-containing metal salt solution, a precipitant and a complexing agent into a base solution for reaction
Data Source
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AI summary
The present application relates to the field of lithium-ion batteries, and provides a lithium-ion battery positive electrode material precursor and a preparation method therefor, a lithium-ion battery positive electrode material, a lithium-ion battery and an electric device. The lithium-ion battery positive electrode material precursor comprises a plurality of primary particles, one primary particle comprises a plurality of neatly stacked single-sheet layers, and the edges of the single-sheet layers are flat, wherein N is a positive integer, and N is greater than or equal to 2. The preparation method for the lithium-ion battery positive electrode material precursor comprises: introducing raw materials including a nickel-containing metal salt solution, a precipitant and a complexing agent into a base solution for reaction, and during the reaction, controlling the pH value to be 9.8-11.3, the ammonia concentration to be 2-12g/L, and the concentration of nickel in a supernatant to be 70-350ppm; and after the reaction, carrying out solid-liquid separation, drying, sieving and demagnetizing to obtain the lithium-ion battery positive electrode material precursor. In the lithium-ion battery positive electrode material precursor, the plurality of single-sheet layers forming the primary particles have the characteristics of high regularity and integrity, and the prepared positive electrode material has higher cycle, capacity and safety.