Positive Electrode Composition for Stable Li-Ion Voltage Platform
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Solution Overview
Problem
Lithium manganese iron phosphate batteries face limitations in energy density and power output stability, hindering their development for electric vehicles and energy storage applications.
Innovation Solution
A positive electrode plate is designed with a specific composition and structure, including a first active material (LiMnmFe1-mPO4) and a second active material (Li1+a[NixCoyMz]O2−bAb), where the area ratio of a bright region in the scanning electron microscope image of the cross-section is controlled between 10% to 70% to optimize voltage platform smoothing and direct current resistance management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium manganese iron phosphate material is used to improve energy density, then energy density increases, but power output stability deteriorates
Solution Approach 1:
The positive electrode active material is segmented into two distinct components: lithium manganese iron phosphate (LiMnmFe1-mPO4) and a layered oxide material (Li1+a[NixCoyMz]O2−bAb). This segmentation allows each material to contribute its strengths - the lithium manganese iron phosphate provides high energy density while the layered oxide maintains voltage stability and reduces resistance fluctuations, thereby resolving the contradiction between energy density improvement and power output stability.
Solution Approach 2:
The invention creates a composite positive electrode active material system by combining lithium manganese iron phosphate with layered oxide material in specific proportions (5% to 95% mass ratio of layered oxide). This composite structure enables the synergistic effect where the layered oxide compensates for the resistance instability of lithium manganese iron phosphate during charge-discharge cycles, achieving both high energy density and stable power output.
2Stability of the object's composition
If the area ratio of bright region is increased to improve voltage platform smoothing, then voltage stability improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention transforms the complex multi-parameter optimization problem into a single critical parameter control - the area ratio of the bright region in the scanning electron microscope image. By establishing a specific range (10% to 70%) for this parameter, the patent simplifies the manufacturing control process while ensuring optimal voltage platform smoothing performance, balancing voltage stability improvement with manageable manufacturing precision requirements.
Data Source
AI summary
The invention provides a positive electrode plate and applications thereof. The positive electrode plate includes a positive electrode current collector, and a positive electrode active layer at least disposed on one side of the positive electrode current collector. The positive electrode active layer includes a first positive electrode active material and a second positive electrode active material. The positive electrode active layer is analyzed with a scanning electron microscope, and in a region with a test area of 50 μm×40 μm, an area of a bright region is 10% to 70% of the test area. Through the positive electrode plate and applications thereof according to the invention, the voltage platform and the sudden increase in direct current resistance of the lithium-ion battery can be improved, and the performance of the lithium-ion battery can be enhanced.