Graphite Coating with Lithium Fluorophosphate for Fast Charging
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Solution Overview
Problem
Current methods for forming a negative electrode in lithium ion secondary batteries with bilayer structures or coating graphite with silicon compounds result in complex production processes and high costs, and there is a need for further improvement in charge rate characteristics.
Innovation Solution
A graphite-based material with a coating film comprising a lithium fluorophosphate compound (LiPOaFb) is used for the negative electrode, where a and b are within specific ranges, formed through heat-treating graphite particles with lithium difluorophosphate, enhancing charge rate characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a bilayer structure with different active materials is used in the negative electrode, then charge rate characteristics are enhanced, but production process complexity increases and production cost increases
Solution Approach 1:
The invention applies local quality by coating only the surface of graphite particles with lithium fluorophosphate compound rather than using a complex bilayer structure throughout the entire electrode. This localized modification at the particle surface level achieves charge rate enhancement while maintaining production process simplicity.
Solution Approach 2:
The invention changes the chemical composition parameter of the graphite surface by forming a coating film of lithium fluorophosphate compound (LiPOaFb) with specific stoichiometric ratios. This parameter change at the surface level improves charge rate characteristics without requiring complex bilayer electrode structures.
2Speed
If graphite edge portions are coated with silicon compounds, then charge rate characteristics are enhanced, but production process complexity increases and production cost increases
Solution Approach 1:
The invention uses lithium fluorophosphate compound as a coating material that can be applied through simple heat treatment, replacing expensive silicon compounds and complex coating processes. The coating forms a functional layer that enhances charge rate at lower cost.
Solution Approach 2:
The invention replaces complex mechanical coating processes with a thermal treatment method where lithium fluorophosphate compound is applied and activated through heat treatment. This substitution simplifies the manufacturing process while achieving the desired surface modification for enhanced charge rate characteristics.
3Speed
If a coating film is formed on graphite surface to improve charge rate characteristics, then charging speed increases, but manufacturing process complexity increases
Solution Approach 1:
The invention merges the coating formation process with the existing graphite particle manufacturing process by applying lithium fluorophosphate compound and forming the coating through heat treatment integrated into the production flow. This consolidation achieves surface modification without adding separate complex manufacturing steps.
Solution Approach 2:
The lithium fluorophosphate compound coating film forms through self-organization during heat treatment of graphite particles in the presence of the compound. The process is self-driven by thermal energy, eliminating the need for complex external coating equipment or multi-step manufacturing procedures while achieving uniform surface coverage for improved charging speed.
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 lithium ion secondary battery exhibits improved charge rate characteristics, allowing for faster charging and increased efficiency, particularly at high capacities.
Implementation Method 1
heat-treating graphite particles in the presence of lithium difluorophosphate to form a coating film comprising a lithium fluorophosphate compound derived from the lithium difluorophosphate
Data Source
AI summary
A graphite-based material for a lithium ion secondary battery, the graphite-based material comprising a coating film on at least a part of the surface of a graphite particle, the coating film comprising a lithium fluorophosphate compound having a specific composition.