Composite Cathode Composition for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Current lithium-ion batteries face limitations in charge capacity and fast-charging performance due to the combination of lithium iron phosphate-based and ternary positive electrode materials, despite improvements in cycling performance and energy density.
Innovation Solution
A positive electrode material composition comprising a phosphate-based material and a ternary material, with specific weight ratios and particle sizes, forms polycrystalline secondary spheres, and includes doping elements to enhance stability and conductivity, thereby improving charge capacity and fast-charging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lithium iron phosphate-based positive electrode material and a ternary positive electrode material are combined, then the cycling performance and energy density are improved, but the charge capacity cannot be improved
Solution Approach 1:
The patent combines lithium iron phosphate-based positive electrode material and ternary positive electrode material in specific weight ratios (30-70 wt% and 70-30 wt% respectively) to create a composite positive electrode material that achieves synergistic effects, improving cycling performance while enhancing charge capacity
Solution Approach 2:
The patent optimizes the weight ratio parameters of the two materials, specifically setting the lithium iron phosphate-based material at 30-70 wt% and ternary material at 70-30 wt%, to achieve the best balance between cycling performance and charge capacity
2Use of energy by moving object
If a layered transition metal oxide is used in ternary positive electrode material, then the energy density is high, but the structural instability during cycling leads to shorter service life
Solution Approach 1:
The patent creates a composite system where lithium iron phosphate-based material (with high stability and long service life) compensates for the structural instability of ternary material, while the ternary material compensates for the lower energy density of lithium iron phosphate-based material
Solution Approach 2:
The patent applies different materials with complementary properties to different extents in the composite structure, allowing each material to contribute its advantageous properties (stability from lithium iron phosphate, energy density from ternary) to the overall system
3Ease of manufacture
If monocrystalline positive electrode materials are used, then the manufacturing process is simple, but the bulk diffusion impedance is high, leading to lower charge capacity
Solution Approach 1:
The patent combines monocrystalline and polycrystalline materials in a composite structure, where the monocrystalline material provides ease of manufacture and the polycrystalline material provides low bulk diffusion impedance and high charge capacity
Data Source
AI summary
A positive electrode material composition, a secondary battery, and an electric apparatus. The positive electrode material composition includes a phosphate-based positive electrode material and a ternary positive electrode material, where a weight of the phosphate-based positive electrode material is denoted as W1; a weight of the ternary positive electrode material is denoted as W2; α=W1/(W1+W2), where 50%≤α≤97%, optionally 70%≤α≤90%; and the phosphate-based positive electrode material is a polycrystalline secondary sphere material and/or the ternary positive electrode material is a polycrystalline secondary sphere material.