Carbon-Coated LiFePO4 Cathode Material with Controlled Raman Ratio
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high conductivity and excellent electrochemical properties, which are crucial for enhancing energy density and capacity, particularly in applications like electric vehicles and power storage systems.
Innovation Solution
A positive electrode active material comprising a compound expressed by Chemical Formula Li a1 Fe x1 B1 y1 PO 4, where 0.8≤a1≤1.2, 0.950≤x1≤0.999, and 0≤y1≤0.05, with a specific Raman spectrum ratio (I D /I G ) of 0.5 to 1.5, is manufactured by mixing an iron phosphate precursor, a lithium source, and a carbon source, followed by calcination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active materials are used, then manufacturing is simpler, but conductivity and electrochemical properties are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Li content (a1 between 0.8 and 1.2) and Fe content (x1 between 0.950 and 0.999) in the olivine-based compound, as well as controlling the carbon coating layer thickness. These parameter optimizations improve conductivity and electrochemical properties while maintaining manufacturability through standard calcination processes.
Solution Approach 2:
The patent creates a composite material structure by coating the olivine-based lithium compound particles with a carbon layer. This composite structure enhances electrical conductivity and electrochemical performance while the carbon coating also protects the active material, resolving the contradiction between performance improvement and manufacturing simplicity.
2Quantity of substance
If energy density is increased, then capacity improves, but conductivity may deteriorate
Solution Approach 1:
The carbon-coated olivine-based compound creates a composite structure that simultaneously achieves high capacity (through optimized Li and Fe content) and high conductivity (through the carbon layer). The carbon coating provides conductive pathways while the optimized composition ensures high lithium ion capacity, resolving this contradiction.
Solution Approach 2:
The patent applies local quality by creating a carbon coating layer specifically on the particle surfaces where conductivity is needed, while maintaining the high-capacity olivine-based composition in the bulk material. This localized approach ensures both high capacity and high conductivity without compromising either property.
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 results in a positive electrode active material with improved conductivity and electrochemical properties, leading to increased pellet density, capacity, and energy density, while maintaining durability and reducing resistance.
Implementation Method 1
a carbon source, followed by calcination... a carbon coating layer may be formed on a particle surface
Implementation Method 2
the positive and negative electrodes each include an active material configured for intercalation and deintercalation of lithium ions
Implementation Method 3
The batteries generate electrical energy caused by oxidation and reduction (i.e., redox) reactions that occur when the lithium ions are intercalated and deintercalated
Data Source
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AI summary
Positive electrode active materials, their manufacturing methods, and rechargeable lithium batteries are provided. A positive electrode active material comprises a first particle that includes a compound represented by Chemical Formula 1 and has a first average particle diameter. A ratio (ID/IG) of intensity (ID) of D peak at a wave number of about 1340±10cm-1 in the Raman spectrum obtained from Raman spectroscopy to intensity (IG) of G peak at a wave number of about 1590±10cm-1 in the Raman spectrum obtained from Raman spectroscopy is in a range of about 0.5 to about 1.5.