Composite Cathode Material Coatings for Low-Temperature Li-Ion Batteries
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high operating voltage, and high conductivity, particularly in maintaining stability and efficiency at low temperatures.
Innovation Solution
A positive electrode active material comprising first particles with an olivine-based lithium compound and second particles with a layered lithium compound, where the first particles have a smaller average diameter and are coated with titanium, magnesium, or vanadium-containing compounds, while the second particles are coated with aluminum or titanium to enhance structural stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single positive electrode material is used, then the structure is simple, but energy density and operating voltage cannot be simultaneously optimized
Solution Approach 1:
The patent employs composite materials by combining olivine-based lithium compound particles (LiMn1-x-yNixCoyPO4) with layered lithium compound particles (LiCoO2 or LiNi0.8Co0.1Mn0.1O2). This composite structure allows the electrode to simultaneously achieve high energy density from the layered compound and high operating voltage with good stability from the olivine compound, resolving the contradiction between structural simplicity and energy performance optimization.
2Quantity of substance
If particle size is increased to improve capacity, then more lithium ions can be stored, but conductivity decreases
Solution Approach 1:
The patent applies local quality by creating a bimodal particle size distribution where small particles (0.5-2 μm) provide high conductivity and fast lithium ion diffusion, while large particles (3-10 μm) provide high capacity. The mixture ratio is optimized so that small particles form a conductive network throughout the electrode, ensuring overall high conductivity while large particles contribute the majority of lithium ion capacity.
3Stability of the object's composition
If binder content is increased to improve structural stability, then electrode integrity is enhanced, but active material content and energy density decrease
Solution Approach 1:
The patent uses thin film coatings on particle surfaces - specifically a first coating layer containing titanium, magnesium, or vanadium compounds and a second coating layer containing aluminum or titanium compounds. These thin protective films provide structural stability and surface protection without significantly increasing mass, allowing the electrode to maintain integrity while preserving high active material content and energy density.
4Use of energy by moving object
If operating voltage is increased to improve energy density, then battery capacity increases, but stability and conductivity deteriorate
Solution Approach 1:
The composite structure combines layered lithium compounds (LiCoO2 or LiNi0.8Co0.1Mn0.1O2) that enable high operating voltage (3.7-4.35 V) and high energy density with olivine-based lithium compounds (LiMn1-x-yNixCoyPO4) that provide exceptional stability and structural integrity. The synergistic combination allows the electrode to operate at high voltages while maintaining stability through the robust olivine framework.
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 combination of these particles improves energy density, operating voltage, and low-temperature performance, with enhanced electrical conductivity and reduced binder usage, resulting in improved capacity retention and voltage stability.
Implementation Method 1
produces electrical energy through the oxidation and reduction reactions when lithium ions are intercalated into and deintercalated from the positive electrode and negative electrode
Data Source
AI summary
Examples of the disclosure include positive electrode active materials for a rechargeable battery, and rechargeable lithium batteries including the positive electrode active materials. For example, the positive electrode active material includes first particles comprising a compound and having a first average particle diameter, and second particles comprising a compound and having a second average particle diameter that is smaller than the first average particle diameter. The content of the first particles is greater than the content of the second particles.