Layered Positive Electrode Structure for Low-Resistance Li Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high energy density and capacity while maintaining strong binding forces between the positive electrode active material layer and the current collector, leading to increased resistance and reduced performance.
Innovation Solution
A positive electrode structure is designed with a layered configuration of first and second active material layers, utilizing a first particle with a layered compound and a second particle with an olivine structured compound, along with specific weight ratios of functional additives and conductive materials, to enhance binding force and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive electrode active material layer is used to increase energy density and capacity, then the binding force with the current collector decreases, but high energy density and capacity are required
Solution Approach 1:
The positive electrode active material layer is divided into multiple layers (first active material layer and second active material layer) with different compositions and functions. The first layer contains particles with specific surface treatments for strong current collector binding, while the second layer contains high-capacity particles, thus segmenting the conflicting requirements of binding strength and energy density across different layers.
Solution Approach 2:
Different regions of the positive electrode active material layer are assigned different local qualities: the first active material layer near the current collector has enhanced adhesive properties through surface treatment, while the second active material layer further from the collector has optimized composition for maximum capacity, allowing each region to optimize for its specific function.
2Strength
If functional additives and conductive materials are increased to improve binding force and reduce resistance, then the weight and complexity of the electrode increase, but binding force and low resistance are critical for performance
Solution Approach 1:
Functional additives and conductive materials are merged into composite particle structures where conductive materials are coated on or incorporated with active material particles. This integration reduces the need for separate additive layers and simplifies the overall electrode structure while maintaining binding force and electrical conductivity.
Solution Approach 2:
The patent employs composite material structures where active material particles are combined with conductive materials and binding agents in specific ratios and configurations. These composite structures provide both mechanical binding strength and electrical conductivity simultaneously, reducing the need for separate functional layers and simplifying electrode composition.
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 improves binding force with the current collector, facilitating electrode preparation and reducing resistance, resulting in rechargeable lithium batteries with enhanced capacity, lifetime, and energy density.
Implementation Method 1
each including an active material that allows intercalation and deintercalation of lithium ions
Implementation Method 2
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
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AI summary
Examples of the disclosure include a positive electrode, and a rechargeable lithium battery including the positive electrode. Examples of the disclosure include a positive electrode for a rechargeable lithium battery including a current collector, a first active material layer on the current collector, the first active material layer including a first particle, a first binder, and a first conductive material, and a second active material layer on the first active material layer, second active material layer including a second particle, a second binder, and a second conductive material. The first particle contains a layered compound, the second particle contains an olivine structured compound, the second particle is a single particle, 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.