Double-Layer Positive Electrode for Low-Temperature Lithium Batteries
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high low-temperature performance, and long lifetime characteristics.
Innovation Solution
A positive electrode for rechargeable lithium batteries is designed with a double-layer structure comprising specific compounds and particles, including a first and second active material layer stacked on a current collector, with each layer containing distinct particles and binders to enhance conductivity and stability.
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 is insufficient
Solution Approach 1:
The active material layer is divided into two distinct layers: a first active material layer containing Li-rich layered oxide particles and a second active material layer containing high-voltage spinel particles. This segmentation allows each layer to contribute different properties (capacity from Li-rich layered oxide, rate performance from spinel) to achieve high energy density without excessive complexity
Solution Approach 2:
The patent employs a composite structure combining two different active materials (Li-rich layered oxide and high-voltage spinel) in a layered configuration. This composite approach leverages the complementary strengths of each material to achieve superior energy density compared to single-material systems
2Quantity of substance
If high-capacity active materials are used, then the energy density increases, but the lifetime characteristics deteriorate
Solution Approach 1:
By separating the high-capacity Li-rich layered oxide (which provides energy density) from the structural stabilization function (provided by the spinel layer), the patent achieves both high capacity and long cycle life. The spinel layer acts as a protective and stabilizing component that mitigates degradation of the Li-rich layered oxide during cycling
Solution Approach 2:
The composite of Li-rich layered oxide and high-voltage spinel creates a synergistic effect where the spinel phase provides structural stability and resistance to degradation, while the Li-rich layered oxide delivers high capacity. This composite structure maintains reliability over extended cycling
3Ease of operation
If conventional active material compositions are used, then the manufacturing process is simple, but the low-temperature characteristics are poor
Solution Approach 1:
The patent modifies the compositional parameters of the active material layer by incorporating specific ratios of Li-rich layered oxide and high-voltage spinel particles with defined particle size ranges and chemical compositions. These parameter optimizations enhance low-temperature ionic conductivity and electrochemical activity without significantly complicating the manufacturing process
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 design achieves high energy density, improved low-temperature characteristics, and extended battery life, enhancing overall performance.
Implementation Method 1
Rechargeable lithium batteries include a positive electrode and a negative electrode, 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
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.