LiMPO4 Cathode Crystal Alignment for Lower Resistance and Higher Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-containing composite oxides in lithium ion secondary batteries have high resistance, limiting the increase of discharge capacity and energy density.
Innovation Solution
A lithium ion secondary battery with a positive electrode active material layer comprising flat single crystal lithium-containing composite oxides (LiMPO4) where the b-axis is shorter than the a-axis and c-axis, and forms a specific angle with the current collector, facilitating easier lithium ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-containing composite oxides with small particle diameters and less variation in particle size are used, then discharge capacity and energy density increase, but internal resistance remains high
Solution Approach 1:
The patent changes the crystal orientation parameters of lithium-containing composite oxides by controlling the hydrothermal synthesis process to make the b-axis perpendicular to the current collector surface, optimizing the arrangement of lithium ion diffusion pathways and reducing internal resistance while maintaining small particle size
Solution Approach 2:
The patent uses composite lithium-containing composite oxides with specific crystal structures (olivine structure) combined with conductive materials in the positive electrode layer, creating a composite structure that reduces internal resistance while maintaining high discharge capacity
2Quantity of substance
If lithium-containing composite oxides with small particle diameters and less variation in particle size are used, then discharge capacity and energy density increase, but power output is limited
Solution Approach 1:
The patent optimizes the crystal orientation parameters by making the b-axis perpendicular to the current collector surface, which shortens the lithium ion diffusion path and improves ion transport kinetics, thereby increasing power output while maintaining high discharge capacity
Solution Approach 2:
The patent transitions from considering only particle size to considering crystal orientation in three-dimensional space, specifically orienting the b-axis perpendicular to the current collector surface, which creates optimal lithium ion diffusion pathways and enhances power output
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 configuration reduces internal resistance and enhances discharge capacity and power output of the lithium ion secondary battery.
Implementation Method 1
facilitating easier lithium ion migration
Data Source
AI summary
A lithium ion secondary battery includes a positive electrode, a negative electrode, and an electrolyte provided between the positive electrode and the negative electrode. The positive electrode includes a positive electrode current collector and a positive electrode active material layer over the positive electrode current collector. The positive electrode active material layer includes a plurality of lithium-containing composite oxides each of which is expressed by LiMPO4 (M is one or more of Fe (II), Mn (II), Co (II), and Ni (II)) that is a general formula. The lithium-containing composite oxide is a flat single crystal particle in which the length in the b-axis direction is shorter than each of the lengths in the a-axis direction and the c-axis direction. The lithium-containing composite oxide is provided over the positive electrode current collector so that the b-axis of the single crystal particle intersects with the surface of the positive electrode current collector.