LiMnPO4 Cathode Material Hydrothermal Synthesis for Battery Performance
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Solution Overview
Problem
Existing methods for producing LiMnPO4 particles for lithium ion batteries face challenges in shortening the crystal lattice length in the b-axis direction, leading to poor charge and discharge characteristics, and are limited in achieving sufficient fineness and stability, especially with mechanical pulverization and high-boiling polyhydric alcohol methods.
Innovation Solution
The method involves setting specific ranges for lattice constants a, b, and c of LiMnPO4 particles to 10.41 Å<a≦10.43 Å, 6.070 Å<b≦6.095 Å, and 4.730 Å<C≦4.745 Å, achieved through hydrothermal synthesis by heating a raw material slurry with a solvent containing water under compression, to produce particles with a shortened b-axis crystal lattice length while maintaining long a-axis and c-axis lengths, resulting in improved Li diffusion and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If mechanical pulverization is used to make LiMnPO4 particles fine, then particle size is reduced, but crystal lattice length in b-axis direction cannot be shortened sufficiently
Solution Approach 1:
The patent applies parameter changes by controlling hydrothermal synthesis conditions (temperature, pressure, time, pH) to achieve specific crystal lattice dimensions. By adjusting these parameters, the crystal lattice length in the b-axis direction is shortened to 6.070-6.095 Å while maintaining a-axis (10.41-10.43 Å) and c-axis (4.730-4.745 Å) lengths, resolving the limitation of mechanical pulverization.
2Volume of moving object
If high-boiling polyhydric alcohol method is used to make particles fine, then particle fineness is improved, but crystal lattice length in b-axis direction remains too long
Solution Approach 1:
The patent changes the synthesis method from high-boiling polyhydric alcohol to hydrothermal synthesis using water-based solvents. By controlling temperature (100-150°C), pressure (0.1-10 MPa), and pH (2-7) parameters in the hydrothermal process, the crystal lattice b-axis length is precisely controlled to 6.070-6.095 Å, achieving both particle fineness and crystal structure optimization.
3Speed
If Li diffusion distance is reduced by shortening b-axis crystal lattice, then charge-discharge characteristics improve, but material utilization remains poor
Solution Approach 1:
The patent optimizes multiple crystal lattice parameters simultaneously (a-axis: 10.41-10.43 Å, b-axis: 6.070-6.095 Å, c-axis: 4.730-4.745 Å) to achieve the optimal balance between Li diffusion distance and material utilization. The shortened b-axis (6.070-6.095 Å) reduces diffusion distance for high-speed charge-discharge, while the maintained a-axis and c-axis lengths preserve structural stability and material utilization.
Solution Approach 2:
The patent creates a composite structure by controlling crystal morphology and particle size distribution. The optimized crystal lattice parameters produce particles with specific morphologies that combine short diffusion paths with high active material content, improving both charge-discharge characteristics and material utilization synergistically.
4Speed
If crystal lattice length in b-axis direction is shortened for high-speed charge-discharge, then Li diffusion improves, but stability and safety at high voltage deteriorate
Solution Approach 1:
The patent precisely controls the crystal lattice parameters within specific ranges (a-axis: 10.41-10.43 Å, b-axis: 6.070-6.095 Å, c-axis: 4.730-4.745 Å) to achieve optimal performance. The b-axis length is shortened to improve Li diffusion, while the a-axis and c-axis lengths are maintained within ranges that preserve structural stability and high-voltage safety, preventing crystal structure collapse during 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
This approach enables lithium ion batteries with enhanced stability, safety at high voltage, high energy density, high load characteristics, and long-term cycle performance by optimizing the crystal structure and size of LiMnPO4 particles for efficient Li diffusion.
Implementation Method 1
a method of producing the same by a hydrothermal synthesis method, including a step of heating raw material slurry obtained by mixing a Li source, a P source, and a Mn source with a solvent containing water as a main component to a temperature within a range of 100° C. to 150° C., and performing synthesis under compression
Data Source
AI summary
Provided is a positive electrode active material for lithium ion batteries, which is capable of realizing stability and safety at a high voltage, a high energy density, high load characteristics, and long-term cycle characteristics by controlling a crystal shape of LiMnPO4 particles having a crystal structure very suitable for Li diffusion or controlling an average primary particle size, a production method thereof, an electrode for lithium ion batteries, and a lithium ion battery. The positive electrode active material for lithium ion batteries of the invention is a positive electrode active material for lithium ion batteries, which is formed from LiMnPO4. Values of lattice constants a, b, and c, which are calculated from an X-ray diffraction pattern, satisfy 10.41 Å<a≦10.43 Å, 6.070 Å<b≦6.095 Å, and 4.730 Å<C≦4.745 Å, and an average particle size is 10 to 100 nm.