Composite Cathode Material Balancing Battery Energy and Cycle Life
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density and extended lifetime while maintaining economic feasibility.
Innovation Solution
A positive electrode active material comprising a combination of first particles with an olivine structure, second particles with a spinel structure, and third particles, optimized in specific elemental compositions and structures, enhances the performance of rechargeable lithium batteries by improving charge and discharge efficiency, structural stability, and lifetime characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single positive electrode active material is used, then the battery structure is simple, but the energy density and lifetime characteristics cannot be simultaneously optimized
Solution Approach 1:
The patent uses a composite positive electrode active material consisting of two distinct particle types: first particles with olivine structure (LiFePO4-based) providing structural stability and long cycle life, and second particles with spinel structure (LiMn2O4-based) providing high capacity and energy density. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both simplicity and enhanced reliability/lifetime characteristics.
2Quantity of substance
If high capacity materials are used to achieve high energy density, then the energy density improves, but the structural stability and lifetime deteriorate
Solution Approach 1:
The patent combines olivine-structured first particles (high structural stability, lower capacity) with spinel-structured second particles (high capacity, lower stability) in specific weight ratios (70-95 wt% first particles, 5-30 wt% second particles). This composite approach achieves high energy density through the high-capacity spinel particles while maintaining structural stability through the stable olivine particles, resolving the contradiction between energy density and structural stability.
Solution Approach 2:
The patent optimizes the weight ratio parameters of the two particle types to balance energy density and structural stability. By adjusting the proportion of high-capacity but less stable spinel particles versus high-stability but lower-capacity olivine particles, the patent achieves the desired energy density while maintaining adequate structural stability and lifetime characteristics.
3Ease of manufacture
If conventional positive electrode materials are used, then the manufacturing cost is low, but the charge and discharge efficiency and lifetime are insufficient
Solution Approach 1:
The patent uses a composite of olivine and spinel structured materials that can be manufactured using conventional ceramic processing techniques, maintaining cost-effectiveness while achieving superior charge-discharge efficiency. The spinel component provides three-dimensional lithium ion diffusion pathways that enhance rate capability and efficiency, while the olivine component maintains structural integrity during cycling, improving lifetime.
4Quantity of substance
If the positive electrode active material is optimized for high capacity, then the energy density improves, but the manufacturing complexity increases
Solution Approach 1:
The patent employs a composite positive electrode active material comprising first particles with olivine structure and second particles with spinel structure in specific weight ratios. This composite structure achieves high capacity while maintaining manufacturing simplicity through conventional ceramic processing techniques, avoiding the need for complex multi-step synthesis procedures.
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 and extended lifetime with improved charge and discharge efficiency, structural stability, and cost-effectiveness in lithium batteries.
Implementation Method 1
Electrical energy is generated through oxidation and reduction reactions when lithium ions are intercalated into and deintercalated from the positive electrode and negative electrode
Data Source
AI summary
A positive electrode active material, a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode are provided. The positive electrode active material includes first particles comprising a compound of Lia1Fex1B1y1PO4-b1 and having an olivine structure, second particles comprising a compound of Lia2Mnx2C1y2O4-b2 and having a spinel structure and third particles comprising a compound of Lia3COx3D1y3O4-b3. The first particles and the second particles constitute a main active material, and the content (e.g., amount) of the main active material is about 95 parts by weight to about 99.5 parts by weight on the basis of about 100 parts by weight of the positive electrode active material.