Carbonaceous Material Adsorption Velocity for Battery Energy Density
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Solution Overview
Problem
Current negative electrode active materials for secondary batteries, such as graphite and hard carbon, have limitations in energy density, service life, and rate performance due to their low gram capacity and first-cycle coulombic efficiency.
Innovation Solution
A carbonaceous material with a water vapor adsorption velocity between 0.015 and 0.050 is developed, which has high gram capacity, high first-cycle coulombic efficiency, and high structural stability, enabling secondary batteries to achieve high energy density, long service life, and good rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If graphite is used as negative electrode active material, then structural stability is improved, but gram capacity is limited to 372 mAh/g which restricts energy density improvement
Solution Approach 1:
The patent uses composite carbonaceous materials combining graphite particles with hard carbon coating layers. The graphite core provides structural stability while the hard carbon outer layer increases gram capacity beyond 372 mAh/g through additional Li-ion insertion sites, resolving the contradiction between structural stability and gram capacity
Solution Approach 2:
The patent employs porous carbonaceous materials with controlled pore structures that allow enhanced Li-ion intercalation while maintaining structural integrity. The porous architecture provides additional storage sites for active ions, increasing gram capacity without compromising the structural stability needed for long cycle life
2Ease of manufacture
If graphite is used as negative electrode active material, then low cost and ease of manufacture are achieved, but interlayer spacing is small which limits rate performance
Solution Approach 1:
The patent modifies the interlayer spacing parameter of graphite by introducing controlled expansions through chemical intercalation or physical doping. This increases the spacing between graphite layers, enabling faster Li-ion diffusion and improving rate performance while maintaining the ease of manufacture associated with graphite-based materials
Solution Approach 2:
The patent creates composite structures where graphite is combined with materials that expand interlayer spacing, such as transition metal compounds or molecular intercalates. This composite approach maintains the manufacturing simplicity of graphite while achieving enhanced rate performance through increased ion transport pathways
3Speed
If hard carbon is used as negative electrode active material, then rapid intercalation and deintercalation of active ions is achieved improving rate performance, but gram capacity and first-cycle coulombic efficiency are low which limits energy density and service life
Solution Approach 1:
The patent uses composite carbonaceous materials combining graphite particles with hard carbon coating layers. The graphite core provides high gram capacity (372 mAh/g) and good first-cycle coulombic efficiency, while the hard carbon outer layer enables rapid Li-ion intercalation and deintercalation, achieving both high rate performance and high gram capacity simultaneously
Solution Approach 2:
The patent applies local quality differentiation by having the hard carbon coating primarily at the particle surfaces and interfaces where ion transport occurs, while the bulk graphite material provides high capacity storage. This localized hard carbon presence enhances rate performance without sacrificing the high gram capacity of the graphite core
4Speed
If hard carbon is used as negative electrode active material, then rapid intercalation and deintercalation of active ions is achieved, but first-cycle coulombic efficiency is low which limits service life
Solution Approach 1:
The patent uses composite carbonaceous materials where the graphite core provides high first-cycle coulombic efficiency (>90%) and the hard carbon coating enables rapid ion transport. This composite structure achieves both high rate performance and high first-cycle coulombic efficiency, improving both service life and rate performance simultaneously
Solution Approach 2:
The patent applies local quality differentiation by having the hard carbon coating primarily at the particle surfaces and interfaces where ion transport occurs, while the bulk graphite material provides high first-cycle coulombic efficiency. This localized hard carbon presence enhances rate performance without significantly reducing the first-cycle coulombic efficiency
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 significantly improves the energy density, service life, and rate performance of secondary batteries by facilitating intercalation, storage, and deintercalation of active ions, while maintaining high structural stability.
Implementation Method 1
The carbonaceous material has an adsorption velocity v that satisfies 0.015≤v≤0.050 when subjected to an adsorption test using water vapor at a constant temperature and humidity of 25° C. and 40% RH
Data Source
AI summary
A carbonaceous material has an adsorption velocity v that satisfies 0.015≤v≤0.050 when subjected to an adsorption test using water vapor at a constant temperature and humidity of 25° C. and 40% RH. The water vapor adsorption test is performed under the following conditions: in a constant temperature and humidity chamber at 25° C. and 40% RH, the carbonaceous material with a mass of m1 is placed in a container, and a water vapor adsorption mass m2 and a water vapor adsorption time t are recorded when the water vapor adsorption of the carbonaceous material reaches equilibrium, and the water vapor adsorption velocity is v=m2/(m1×t), where mi is measured in g, m2 is measured in g, and t is measured in h.