Dual-Particle Cathode Material for High-Voltage Li-Ion Batteries
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high operating voltage, and low-temperature performance, as well as charge and discharge efficiency.
Innovation Solution
A positive electrode active material comprising first and second particles with specific chemical compositions and particle diameters, mixed in a certain ratio, and a conductive material and binder, forming a positive electrode layer in a lithium battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single particle size of positive electrode active material is used, then the manufacturing process is simple, but the energy density and charge/discharge efficiency are limited
Solution Approach 1:
The positive electrode active material is segmented into two distinct particle size ranges: first particles with 0.4-10 μm diameter and second particles with 10-50 μm diameter. This segmentation allows small particles to provide high surface area for fast charge/discharge while large particles contribute to high energy density, resolving the contradiction between charge/discharge efficiency and energy density without requiring complex multi-size distributions.
Solution Approach 2:
The invention changes the particle size parameter by establishing specific diameter ranges for two particle types rather than using a continuous distribution. The first particles (0.4-10 μm) optimize for electrochemical activity while second particles (10-50 μm) optimize for capacity, creating a binary size distribution that simplifies manufacturing while achieving superior performance metrics.
2Quantity of substance
If high capacity positive electrode active material is used, then the energy density increases, but the operating voltage decreases
Solution Approach 1:
The positive electrode uses a composite of two particle types with different capacity-voltage characteristics. The first particles (0.4-10 μm) with formula Li a1 Mn b1 Fe x1 B y1 PO 4-c1 provide high operating voltage through boron doping, while second particles (10-50 μm) with formula Li a2 Fe b2 O c2 provide high lithium ion capacity. This composite approach allows the electrode to achieve both high energy density and high operating voltage simultaneously.
Solution Approach 2:
Different regions of the positive electrode have different particle size and composition qualities. The first particles with optimized composition for voltage are distributed throughout, while second particles with optimized composition for capacity are also distributed. This local quality differentiation allows each particle type to contribute its optimal property to the overall electrode performance.
3Productivity
If room temperature performance is optimized, then the charge/discharge efficiency is high, but the low-temperature characteristics deteriorate
Solution Approach 1:
The invention changes the compositional parameters by introducing boron doping (0.001≤y1≤0.05) in the first particles and optimizing the Li:Fe ratio in the second particles. These parameter changes enhance ionic conductivity and reduce activation energy for lithium ion insertion/extraction, allowing the electrode to maintain high charge/discharge efficiency across a wide temperature range from -30°C to 45°C.
Solution Approach 2:
The composite structure combines first particles with boron-doped spinel structure and second particles with lithiated iron oxide structure. This composite material approach creates synergistic effects where the boron-doped particles provide stable voltage and the lithiated iron oxide particles provide high capacity, together achieving both room temperature efficiency and low-temperature adaptability.
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 solution enhances the battery's energy density, operating voltage, and charge/discharge efficiency, while improving low-temperature characteristics.
Implementation Method 1
Electrical energy is generated (produced) through the oxidation and reduction reactions when lithium ions are intercalated into and deintercalated from the positive and negative electrodes
Data Source
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AI summary
Positive electrode active materials for a rechargeable battery, positive electrodes including the positive electrode active material, and rechargeable lithium batteries including the positive electrode are provided. A positive electrode active material includes first particles including a compound represented by Chemical Formula 1 and having a first average particle diameter, and second particles including a compound represented by Chemical Formula 2 and having a second average particle diameter that is greater than the first average particle diameter. A mixing ratio of the first particles and the second particles is about 95:5 to about 99.5:0.5.