Double-Layer Positive Electrode for Capacity and Cycle Life
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density and capacity while maintaining stable electrode bindability and lifetime characteristics.
Innovation Solution
A positive electrode structure comprising a double-layered active material configuration with specific olivine and layered compounds, along with optimized binder and conductive material ratios, enhances bindability and improves capacity and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer active material structure is used, then the electrode structure is simple, but the bindability between current collector and active material is insufficient
Solution Approach 1:
The positive electrode active material layer is divided into a first active material layer and a second active material layer. The first layer contains olivine structured compound particles with average diameter of 3 μm to 10 μm, while the second layer contains layered compound particles with average diameter of 5 μm to 15 μm. This segmentation allows each layer to contribute differently to bindability and capacity, resolving the contradiction between structural simplicity and binding reliability.
2Quantity of substance
If high capacity active materials are used, then the energy density increases, but the lifetime characteristics deteriorate
Solution Approach 1:
The patent employs a composite structure combining two different active materials: olivine structured compound (Li1+xM1-yM′yPO4) in the first layer and layered compound (Li1+xM1-yM′yO2) in the second layer. Each material contributes complementary properties - the olivine structure provides structural stability for long cycle life, while the layered structure delivers high capacity. This composite approach resolves the contradiction between high capacity and long lifetime.
3Ease of manufacture
If the ratio of functional additives is not optimized, then the manufacturing process is simple, but the electrode plate preparation difficulty increases
Solution Approach 1:
The patent specifies precise weight ratio parameters for functional additives: the first functional additive (binder + conductive material) comprises 2-5 wt% of the first active material layer, while the second functional additive comprises 3-7 wt% of the second active material layer. By optimizing these parameter ranges, the patent achieves good bindability and electrode plate preparation characteristics without excessive manufacturing complexity.
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 electrode structure achieves improved electrode plate preparation, increased capacity, and enhanced lifetime characteristics by optimizing the bindability and conductivity of the electrode materials.
Implementation Method 1
a first binder and a first conductive material, and a second binder and a second conductive material, wherein the first binder and the first conductive material constitute a first functional additive, the second binder and the second conductive material constitute a second functional additive
Implementation Method 2
each of the positive electrode and the negative electrode including an active material that allows intercalation and deintercalation of lithium ions
Implementation Method 3
produce electrical energy from redox reactions that take place as lithium ions are intercalated into or deintercalated from the positive electrode and the negative electrode
Data Source
AI summary
Examples of the disclosure include a positive electrode, and a rechargeable lithium battery including the positive electrode. Examples include a positive electrode for a rechargeable lithium battery including a current collector, a first active material layer on the current collector, and a second active material layer on the first active material layer. The first active material layer includes a first particle containing an olivine structured compound, a second particle containing a layered compound, a first conductive material, and a first binder. The second active material layer includes a third particle containing an olivine structured compound, a second conductive material, and a second binder.