Porous Carbonaceous Anodes Balancing Capacity and Initial Efficiency
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Solution Overview
Problem
Current secondary battery technologies, particularly those using graphite as the negative electrode active material, face limitations in energy density, service life, and rate performance due to graphite's low theoretical capacity and small interlayer spacing, which restricts the improvement of these parameters in secondary batteries.
Innovation Solution
A carbonaceous material with a specific water vapor adsorption ratio (0.13≤A/B≤0.50) and tailored structural properties, including true density, pore structures, and Raman spectra characteristics, is developed to enhance the capacity and initial coulombic efficiency, enabling higher energy density, longer service life, and better rate performance in secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If graphite is used as negative electrode active material, then the secondary battery can achieve good structural stability, but the energy density is limited due to low theoretical capacity (372 mAh/g)
Solution Approach 1:
The patent employs hard carbon material with a porous structure containing micro-pores and meso-pores. The porous structure provides additional storage spaces for active ions beyond the interlayer spaces, enabling higher capacity while maintaining structural stability. The pore sizes are specifically controlled to facilitate ion transport and storage.
Solution Approach 2:
The patent uses hard carbon as a composite material that combines the structural stability of carbon with a porous architecture. This composite structure integrates the advantages of both ordered graphite-like regions (for stability) and disordered porous regions (for high capacity), resolving the contradiction between capacity and structural stability.
2Speed
If graphite is used as negative electrode active material, then the secondary battery can achieve good structural stability, but the rate performance is limited due to small interlayer spacing
Solution Approach 1:
The patent transitions from the two-dimensional interlayer spacing limitation of graphite to a three-dimensional porous structure. The porous architecture provides multiple dimensional pathways for ion transport, eliminating the bottleneck of small interlayer spacing while preserving structural stability through the carbon framework.
Solution Approach 2:
The hard carbon material's porous structure with controlled pore sizes creates additional diffusion pathways and reduces transport resistance. The pores allow faster ion access to storage sites compared to graphite's limited interlayer channels, thereby improving rate performance while maintaining structural integrity.
3Quantity of substance
If hard carbon is used as negative electrode active material, then the rate performance is improved due to rapid intercalation and deintercalation, but the capacity and initial coulombic efficiency are relatively low
Solution Approach 1:
The patent optimizes specific parameters of the hard carbon material, including pore size distribution, surface area, and structural characteristics. By controlling these parameters within specific ranges, the material achieves both high capacity and improved initial coulombic efficiency, resolving the trade-off between the two performance metrics.
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 carbonaceous material achieves improved capacity and initial coulombic efficiency, leading to secondary batteries with enhanced energy density, extended service life, and superior rate performance by optimizing storage space for active ions and structural stability.
Implementation Method 1
A represents a mass of water vapor adsorbed on the carbonaceous material after a water vapor adsorption test by placing the carbonaceous material under constant temperature and humidity conditions of 25° C. and 100% RH for 100 h
Data Source
AI summary
The present application provides a carbonaceous material and a preparation method therefor, and a secondary battery and an electrical device comprising the same. The carbonaceous material has 0.13≤A/B≤0.50, wherein A represents a mass of water vapor adsorbed on the carbonaceous material after a water vapor adsorption test by placing the carbonaceous material under constant temperature and humidity conditions of 25° C. and 100% RH for 100 h, and B represents an initial mass of the carbonaceous material. The present application can simultaneously improve the capacity and initial coulombic efficiency of the carbonaceous material.