Carbon Electrode Active Material with Basic Functional Groups
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Solution Overview
Problem
Conventional electrode active materials for electrical storage devices, such as lithium ion secondary batteries and lithium ion capacitors, fail to exhibit excellent characteristics at low temperatures, particularly due to increased irreversible capacity and decreased cycle characteristics.
Innovation Solution
An electrode active material with a carbon-based composite structure, featuring 0.020 to 0.20 mmol/g of basic functional groups, is developed, comprising a core-forming carbon material and a coating carbon material, which is produced by mixing and calcining carbon particles with a nitrogen-containing organic compound to enhance low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If graphite particles are used as negative electrode active material, then high energy density characteristics are achieved, but irreversible capacity increases and cycle characteristics decrease due to electrolytic solution decomposition reaction on the particle surface
Solution Approach 1:
The patent uses composite carbon particles comprising a core carbon material and a coating carbon material. The coating layer contains basic functional groups (such as nitrogen-containing groups) that modify the particle surface properties, reducing electrolytic solution decomposition while maintaining high energy density characteristics of graphite particles.
Solution Approach 2:
The patent modifies the surface chemical properties of carbon particles by introducing basic functional groups with specific amounts (0.003 to 0.030 mmol/g). This parameter change in surface chemistry reduces the harmful decomposition reactions while preserving the electrochemical performance.
2Adaptability or versatility
If conventional electrode active materials are used, then standard performance is achieved, but excellent characteristics at low temperatures cannot be realized
Solution Approach 1:
The patent introduces basic functional groups with specific amounts (0.003 to 0.030 mmol/g) on the carbon particle surface, which modifies the electrochemical properties and enables excellent low-temperature performance while maintaining good cycle characteristics.
Solution Approach 2:
The patent applies functional group modification specifically on the particle surface through the coating layer, creating local chemical property changes that improve low-temperature electrolyte behavior without affecting the bulk properties of the carbon material.
3Quantity of substance
If graphite particles with high surface activity are used, then high capacity is achieved, but electrolytic solution decomposition reaction occurs on the particle surface
Solution Approach 1:
The coating carbon material acts as an intermediary layer between the core graphite particles and the electrolytic solution. This intermediate layer contains basic functional groups that prevent direct harmful interactions while allowing beneficial electrochemical reactions to proceed.
Solution Approach 2:
The patent creates composite particles with a core-coating structure where the coating layer modifies the surface properties to reduce electrolytic solution decomposition while maintaining the high capacity characteristics of the core graphite material.
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 electrode active material achieves low internal resistance and excellent cycle characteristics at low temperatures, making it suitable for lithium ion secondary batteries and lithium ion capacitors, while maintaining electrode strength and charge/discharge efficiency.
Implementation Method 1
a coating carbon material for coating at least part of the core-forming carbon material
Implementation Method 2
having 0.020 mmol/g to 0.20 mmol/g of basic functional groups... allow electrical storage devices to exhibit low internal resistance at low temperatures
Data Source
Figure 1
AI summary
The present invention relates to an electrode active material, an electrode and an electrical storage device. The electrode active material includes a carbon material and has not less than 0.020 mmol/g of basic functional groups.