Double-Layer Positive Electrode for Cold-Resistant Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high energy density, high low-temperature performance, and long lifetime characteristics, which are essential for applications in battery-powered electronics and electric vehicles.
Innovation Solution
A positive electrode for lithium batteries is designed with a double-layer structure comprising a first active material layer containing Li a1 Mn z1 Fe x1 B1 y1 PO 4-b1 , a second active material layer containing Li a2 Mn z2 Fe x2 B2 y2 PO 4-b2 , and a third active material layer containing Li a3 Ni x3 Co y3 Mn z3 B3 O 2-b3 , along with specific binders and conductive materials, enhancing the electrode's stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single-layer active material structure is used, then the device complexity is low, but the energy density and performance characteristics are insufficient
Solution Approach 1:
The positive electrode active material layer is segmented into two distinct layers: a first active material layer containing Li a1 Mn z1 Fe x1 B1 y1 PO 4-b1 and a second active material layer containing Li a2 Mn z2 Fe x2 B2 y2 PO 4-b2. Each layer uses different binders and conductive materials optimized for its specific active material, allowing independent optimization of performance characteristics while maintaining manageable structural complexity.
Solution Approach 2:
The patent employs composite material structures by combining different lithium iron phosphate-based active materials with specific binder-conductive material combinations in each layer. The first layer uses a first binder with first conductive material, while the second layer uses a second binder with second conductive material, creating composite electrode structures that enhance overall energy density and performance.
2Reliability
If conventional single-particle-type active material layers are used, then the manufacturing process is simple, but the low-temperature performance and lifetime characteristics are poor
Solution Approach 1:
Different regions of the electrode (first layer vs. second layer) are assigned different active material compositions and binder-conductive material combinations tailored to specific performance requirements. This local optimization allows the first layer to contribute to low-temperature performance while the second layer enhances lifetime characteristics, with each layer's properties optimized for its specific function.
Solution Approach 2:
The patent systematically varies multiple parameters including active material composition (Li a1 Mn z1 Fe x1 B1 y1 PO 4-b1 vs. Li a2 Mn z2 Fe x2 B2 y2 PO 4-b2), binder type, and conductive material selection between layers to achieve superior low-temperature performance and lifetime characteristics compared to conventional single-layer structures.
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 double-layer structure improves the energy density, low-temperature performance, and lifetime of the rechargeable lithium batteries, making them suitable for high-capacity applications in various electronic devices and electric vehicles.
Implementation Method 1
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 for a rechargeable lithium battery, 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 and a third particle, the second active material layer includes a first particle and a second particle, the first particle is in the form of a single particle, and the second particle is in the form of a secondary particle. The first particle and the second particle are olivine-based particles, and the third particle is a layered particle.