Layered Positive Electrode Materials for High-Voltage Li-Ion Batteries
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high average voltage, and excellent lifetime while maintaining economic viability.
Innovation Solution
A positive electrode active material comprising a combination of olivine-structured and spinel-structured lithium compounds, with specific elemental compositions and structural forms, is used in a layered configuration, along with conductive and binder additives, to enhance electrical conductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single positive electrode active material is used, then the electrode structure is simple and manufacturing is easier, but the energy density, average voltage, and lifetime cannot be simultaneously optimized
Solution Approach 1:
The positive electrode is divided into two distinct layers: a first positive electrode active material layer containing olivine-structured lithium compound particles, and a second positive electrode active material layer containing spinel-structured lithium compound particles. This segmentation allows each layer to contribute different properties (energy density from olivine, voltage and stability from spinel) to achieve optimized overall performance without requiring a single complex material
Solution Approach 2:
The patent employs a composite structure combining two different lithium compound materials with distinct crystal structures (olivine and spinel) in separate layers. This composite approach leverages the complementary strengths of each material type to simultaneously achieve high energy density, high average voltage, and excellent lifetime performance
2Quantity of substance
If high energy density materials are used, then the battery capacity increases, but the structural stability and lifetime deteriorate
Solution Approach 1:
By separating the electrode into two layers with different material functions, the patent assigns the high capacity function to the first layer (olivine-structured lithium compound) and the structural stability function to the second layer (spinel-structured lithium compound), allowing both high capacity and stability to coexist without compromising either
Solution Approach 2:
Different regions of the positive electrode are assigned different material properties: the first layer near the current collector provides high lithium ion capacity, while the second layer provides structural stability and voltage enhancement. This local differentiation of material quality allows the system to achieve both high capacity and stability simultaneously
3Productivity
If multiple active materials are combined in layers, then energy density and voltage improve, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the positive electrode into two manageable layers that can be manufactured separately and then assembled, making the complex multi-material structure feasible for production. Each layer can be prepared using standard coating and drying processes, reducing the overall manufacturing complexity despite the multi-material 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 solution provides a positive electrode with high energy density, high average voltage, and improved lifetime, while being economical, through optimized particle structures and additive compositions.
Implementation Method 1
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
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AI summary
Provided are a positive electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same, and for example, a positive electrode for a rechargeable lithium battery, including a current collector, a first positive electrode active material layer on the current collector, and a second positive electrode active material layer on the first positive electrode active material layer. The first active material layer includes a first particle represented by Formula 1 and having the form of a single particle and a second particle represented by Formula 2, and the second positive electrode active material layer includes a third particle represented by Formula 3 and having the form of a secondary particle in which a plurality of primary particles are aggregated. The first particle is present in a greater content than the second particle.