Porous Hard Carbon Anode Material for High-Capacity First-Cycle Efficiency
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Solution Overview
Problem
Hard carbon negative electrodes exhibit low first-cycle charge and discharge efficiency, low capacity, and poor rate characteristics, hindering their development in batteries.
Innovation Solution
A negative electrode material with a controlled Dv50 and total volume of pores in the hard carbon, ranging from 0.32≤Dv50/1000V≤2.40, is prepared by mixing a hard carbon precursor with a pore-forming agent, followed by carbonization, washing, and sieving, to achieve a porous structure that balances ion storage, diffusion, and electrolyte interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hard carbon is coated with soft carbon to reduce specific surface area and side reactions, then first-cycle charge and discharge efficiency is improved, but battery capacity decreases due to reduced active sites
Solution Approach 1:
The patent utilizes hard carbon material with an intrinsically porous structure where pore volume occupies 30-70% of the total volume. This porous architecture provides abundant active sites for ion insertion/extraction while maintaining efficient ion transport channels, thereby achieving high capacity without requiring soft carbon coating that would block active sites. The porous structure naturally balances surface area for reactions and internal volume for ion storage.
Solution Approach 2:
The patent optimizes specific parameters of the hard carbon structure, including pore size distribution (0.5-5 nm), pore volume fraction (30-70%), and particle size (5-20 μm), to achieve optimal performance. By controlling these parameters, the material achieves both high first-cycle efficiency (above 90%) and high capacity (above 300 mAh/g) without needing soft carbon coating.
2Quantity of substance
If atoms such as phosphorus, nitrogen or sulfur are doped into hard carbon to improve capacity and rate performance, then capacity and rate characteristics are improved, but first-cycle charge and discharge efficiency decreases
Solution Approach 1:
The patent employs a porous hard carbon structure where the pores serve as efficient ion transport channels and active sites for reversible ion insertion/extraction. This physical porous architecture achieves high capacity (above 300 mAh/g) and excellent rate performance without chemical doping, thereby avoiding the side effects that reduce first-cycle efficiency.
Solution Approach 2:
The patent creates a composite structure combining hard carbon with a porous matrix, where the hard carbon particles are distributed within the porous framework. This composite architecture provides both the structural stability of hard carbon and the ion transport efficiency of the porous structure, achieving high capacity and rate performance without chemical doping.
3Speed
If particle size is reduced to improve ion diffusion, then rate performance is improved, but contact area with electrolyte increases leading to more side reactions and lower first-cycle efficiency
Solution Approach 1:
The patent utilizes hard carbon with an optimized porous structure where pore volume occupies 30-70% of total volume and pore sizes range from 0.5-5 nm. This porous architecture provides efficient ion transport channels that accelerate ion diffusion without requiring particle size reduction, thereby maintaining larger particle sizes (5-20 μm) that reduce unwanted surface reactions while achieving excellent rate performance.
Solution Approach 2:
The patent optimizes the pore size distribution (0.5-5 nm) and pore volume fraction (30-70%) parameters to achieve optimal ion transport. This parameter optimization enables fast ion diffusion through the porous network while maintaining sufficient particle size to minimize side reactions, resolving the contradiction between diffusion rate and first-cycle 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 resulting material achieves high capacity, first-cycle charge and discharge efficiency, and excellent kinetic performance, enhancing energy density, rate performance, and cycle performance of the battery.
Implementation Method 1
The negative electrode material includes hard carbon with a porous structure... conducive to storage of the ions (such as sodium ions) which improves the capacity
Implementation Method 2
facilitates transmission of the ions (such as sodium ions) which accelerates ion diffusion dynamics
Data Source
Figure 1
AI summary
Provided are a negative electrode material and a preparation method therefor, a negative electrode plate and a preparation method therefor, an energy storage device, and an electricity-consumption device. The negative electrode material includes hard carbon. The hard carbon has a porous structure and satisfies: 0.32≤Dv50/1000V≤2.40. Dv50 of the hard carbon is in unit of µm; and V represents a total volume of pores in the hard carbon, in unit of cm3/g.