Novolac Resin Coated Graphite for Battery Efficiency
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Solution Overview
Problem
Conventional carbonaceous substance-coated graphite particles used as negative electrode materials for lithium ion secondary batteries often exhibit insufficient initial charging-discharging efficiency and cycle characteristics.
Innovation Solution
The development of carbonaceous substance-coated graphite particles with a specific fine structure, achieved by forming a carbonaceous coating using a xylene-modified novolac-type phenolic resin, which covers at least part of the graphite particles, optimizing particle diameter, specific surface area, and pore structure for enhanced battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbonaceous substance-coated graphite particles are used as negative electrode material, then the structure is simple and manufacturing is easy, but the initial charging-discharging efficiency and cycle characteristics are insufficient
Solution Approach 1:
The patent applies composite materials by combining graphite particles with a specifically designed carbonaceous coating layer. The coating has a controlled pore structure and is formed from novolac-type phenolic resin, creating a composite structure that improves initial charging-discharging efficiency and cycle characteristics while maintaining structural integrity
Solution Approach 2:
The patent utilizes porous materials by creating a carbonaceous coating with a controlled pore structure. The pore volume ratio and pore size distribution are optimized to enhance lithium ion insertion and extraction, thereby improving battery performance without excessive structural complexity
2Reliability
If a carbonaceous coating is formed to improve battery properties, then the initial charging-discharging efficiency improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-forming the carbonaceous coating on graphite particles before electrode fabrication. The coating is applied in advance using a slurry method, allowing the core graphite structure to be prepared separately and then coated, which simplifies the overall manufacturing process while ensuring consistent coating quality
Solution Approach 2:
The patent utilizes parameter changes by optimizing the pore volume ratio (0.3-1.5 mL/g) and pore size distribution of the carbonaceous coating. By controlling these parameters within specific ranges, the initial charging-discharging efficiency is improved while maintaining a manufacturable process through standardized slurry preparation and drying conditions
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 resulting carbonaceous substance-coated graphite particles demonstrate excellent battery properties, including improved initial charging-discharging efficiency and cycle characteristics, when used as a negative electrode material in lithium ion secondary batteries.
Implementation Method 1
a carbonaceous coating is formed using a xylene-modified novolac-type phenolic resin
Implementation Method 2
a specific surface area determined by the BET method is 4.0 to 15.0 m2
Data Source
Figure 1
AI summary
Resin-adhered graphite particles are obtained by causing a modified novolac-type phenolic resin to adhere to graphite particles. At least part of surfaces of the graphite particles is coated with a carbonaceous coating by heating the resin-adhered graphite particles in a non-oxidizing atmosphere at 900 to 1,500°C to carbonize the modified novolac-type phenolic resin. Arylene groups having hydroxy groups account for 5 to 95 mol% of arylene groups constituting the modified novolac-type phenolic resin. The obtained carbonaceous substance-coated graphite particles exhibit excellent battery properties when used as a negative electrode material for a lithium ion secondary battery.