Dual-Layer Positive Electrode Active Material for Low-Temperature Li Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high operating voltage, and low-temperature performance.
Innovation Solution
A positive electrode for rechargeable lithium batteries is designed with a dual-layer structure, comprising a first active material layer of monolithic single particles and a second active material layer of aggregated secondary particles, both containing specific olivine-based lithium compounds, with varying elemental compositions and binder and conductive material contents to enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer structure with uniform particles is used, then the electrode structure is simple, but the energy density and operating voltage are limited
Solution Approach 1:
The positive electrode is divided into two distinct layers: a first active material layer containing single particles and a second active material layer containing secondary particles. This segmentation allows each layer to contribute differently to the overall performance, with the first layer providing high conductivity and the second layer providing high capacity, thereby resolving the contradiction between structural simplicity and energy density.
Solution Approach 2:
The invention transitions from a single-layer structure to a two-layer structure, adding a dimensional aspect to the electrode design. This dimensional change enables the incorporation of different particle types and compositions in each layer, achieving higher energy density and operating voltage without excessive complexity.
2Quantity of substance
If high capacity materials are used to increase energy density, then the operating voltage decreases
Solution Approach 1:
Different regions of the positive electrode are assigned different qualities: the first active material layer uses single particles with specific composition ratios optimized for high operating voltage and conductivity, while the second active material layer uses secondary particles with composition ratios optimized for high capacity. This local differentiation resolves the contradiction between energy density and operating voltage by allowing each layer to excel in its specific function.
Solution Approach 2:
The positive electrode employs a composite structure combining two types of active material layers with different particle morphologies and compositions. The first layer contains single particles with higher lithium content ratios for voltage stability, while the second layer contains secondary particles with optimized capacity characteristics, creating a composite material system that achieves both high energy density and high operating voltage.
3Ease of manufacture
If conventional particle structures are used, then manufacturing is simple, but low-temperature performance is poor
Solution Approach 1:
The invention optimizes specific parameters of the active materials, including the ratio of lithium to transition metal elements, particle size distribution, and composition ratios of different metal elements in the spinel and olivine structures. These parameter changes enhance ionic conductivity and electrochemical activity at low temperatures while maintaining manufacturability through conventional synthesis methods.
Solution Approach 2:
The dual-layer composite structure combines materials with complementary properties: the first layer provides a stable framework with high conductivity, while the second layer provides high capacity with optimized low-temperature characteristics. This composite approach improves low-temperature performance without 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 dual-layer structure achieves high energy density, high operating voltage, and improved low-temperature performance, enhancing the overall efficiency and reliability of rechargeable lithium batteries.
Implementation Method 1
These batteries generate electrical energy through 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
A positive electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same are provided. A positive electrode for a rechargeable lithium battery includes 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 in the form of a single particle, and the second active material layer includes a second particle in the form of a secondary particle. The first particle includes a compound of Formula 1, and the second particle includes a compound of Formula 2, provided herein.