Composite Cathode Material for High-Voltage Lithium Battery Stability
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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.
Innovation Solution
A positive electrode active material comprising first particles of Li a1 Mn x1 Fe y1 B z1 PO 4-c1 and second particles of Li a2 Ni x2 Mn y2 O c2, with the first particles being in a greater content and in single particle form, along with a conductive material and binder, to enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity positive electrode active materials are used, then energy density is improved, but structural stability and lifetime characteristics deteriorate
Solution Approach 1:
The positive electrode active material is divided into two distinct particle types: first particles (olivine structure with high structural stability) and second particles (spinel structure with high capacity). This segmentation allows each particle type to fulfill its specific function - the first particles provide structural framework and stability, while the second particles contribute high capacity, thereby resolving the contradiction between structural stability and energy density
Solution Approach 2:
The invention creates a composite positive electrode active material comprising both olivine-structured first particles and spinel-structured second particles. This composite structure combines the advantages of both material systems: the olivine structure provides dimensional stability and structural integrity during lithium insertion/extraction, while the spinel structure contributes high specific capacity, achieving both structural stability and high energy density simultaneously
2Quantity of substance
If high operating voltage is pursued, then energy density is improved, but low-temperature properties deteriorate
Solution Approach 1:
The invention optimizes the compositional parameters of both particle types and their ratio. The first particles use specific ratios of Mn, Fe, and B elements to balance voltage and conductivity, while the second particles use controlled Ni and Mn ratios. The overall composition ratio (first particles:second particles = 95:5 to 65:35) is optimized to achieve high operating voltage through the olivine phase while the spinel phase maintains low-temperature ionic conductivity, resolving the voltage-temperature property contradiction
3Ease of manufacture
If conventional positive electrode active materials are used, then manufacturing is simple, but energy density and conductivity are insufficient
Solution Approach 1:
The invention performs preliminary classification of the positive electrode active material into two distinct particle size ranges before electrode fabrication. First particles are controlled at 3 μm to 15 μm and second particles at 1.5 μm to 6 μm. This preliminary size differentiation simplifies subsequent manufacturing processes by pre-optimizing the particle characteristics for their respective functions, eliminating the need for complex post-processing while achieving high energy density and conductivity
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 results in a rechargeable lithium battery with improved energy density, operating voltage, and low-temperature properties, enhancing charge and discharge efficiency and lifetime characteristics.
Implementation Method 1
The battery produces electrical energy through the oxidation and reduction reactions if (e.g., when) lithium ions are intercalated into and deintercalated from the positive electrode and the negative electrode
Data Source
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AI summary
A positive electrode active material for a rechargeable lithium battery, a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode are disclosed. For example, the positive electrode active material includes first particles including a compound of Chemical Formula 1 and second particles including a compound of Chemical Formula 2. The content (e.g., amount) of the first particles is greater than the content (e.g., amount) of the second particles, and the second particles are (e.g., be in) a single particle form.