Composite Cathode Material for High-Voltage Lithium 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.
Innovation Solution
A positive electrode active material comprising a first particle with an olivine-based lithium compound (Li a1 Mn x1 Fe y1 PO 4-b1 ) and a second particle with a lithium nickel-based compound (Li a2 Ni x2 Co y2 Mn z2 O 2-b2 ) is developed, where Mn content in the second particle is 1 to 5 times that of the first particle, enhancing structural stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single positive electrode active material is used, then the battery structure is simple, but it is difficult to achieve high energy density, high operating voltage, and low-temperature performance simultaneously
Solution Approach 1:
The positive electrode active material is segmented into two distinct particle types: first particles with olivine-based lithium compound (Li a1 Mn x1 Fe y1 PO 4-b1) providing structural stability and safety, and second particles with lithium nickel-based compound (Li a2 Ni x2 Co y2 Mn z2 O 2-b2) providing high capacity and voltage. This segmentation allows each particle type to specialize in specific performance aspects, achieving high energy density and low-temperature performance while maintaining a relatively simple overall battery structure.
Solution Approach 2:
The patent uses composite materials by combining two different positive electrode active materials with distinct chemical compositions and structures. The olivine-based compound provides thermal stability and structural integrity, while the nickel-based compound contributes high operating voltage and capacity. This composite approach enables the battery to achieve multiple performance targets simultaneously without requiring complex electrode architectures.
2Stability of the object's composition
If high Mn content is used to improve structural stability, then structural stability improves, but energy density decreases
Solution Approach 1:
Different regions of the positive electrode are assigned different Mn contents based on their functional requirements. The first particles (olivine-based) have higher Mn content (x1: 0.1-0.3) to provide structural stability and thermal resistance, while the second particles (nickel-based) have lower Mn content (z2: 0.05-0.2) to maintain high capacity and voltage. This local quality differentiation resolves the contradiction by optimizing Mn distribution according to specific functional needs in different particle types.
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 proposed active material achieves high energy density, high operating voltage, and improved low-temperature properties, along with increased capacity and reduced resistance.
Implementation Method 1
The rechargeable lithium battery produces electrical energy 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, methods for preparing the same, and rechargeable lithium batteries including the same are disclosed. A positive electrode active material includes a first particle including a compound represented by Chemical Formula 1, and a second particle including a compound represented by Chemical Formula 2. Here, the Mn content (e.g., amount) of Chemical Formula 2 is 1 to 5 times the Mn content (e.g., amount) of Chemical Formula 1 based on 100 mol% of transition metals (e.g., all metals excluding lithium).