Porous Core-Shell Anode Material for Battery Volume Expansion
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Solution Overview
Problem
Existing anode materials with mesoporous carbon coatings have low porosity and small pore sizes, leading to inadequate volume expansion management during charging and discharging, resulting in poor electrical cycle performance and low initial charge-discharge efficiency.
Innovation Solution
An anode material with a porous core-shell structure is developed, featuring a carbonaceous core coated with a carbon shell containing amorphous carbon, cobalt, and tin, with a porosity greater than 10%, which allows for effective volume expansion and improved electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Sn anode material is coated with mesoporous carbon, then specific capacity is improved, but porosity is low and pore size is small which cannot well ease volume expansion
Solution Approach 1:
The patent applies porous materials by constructing a carbon shell with controlled porosity (greater than 10%) and appropriate pore size (50-200 nm) that can effectively accommodate the volume expansion of Sn during lithiation. The porous structure provides sufficient void space to absorb expansion stress while maintaining electrical conductivity and ion transport pathways.
Solution Approach 2:
The patent employs composite materials by combining Sn with a carbonaceous material core and a porous carbon shell containing Co and Sn elements. This core-shell composite structure leverages the high capacity of Sn, the stability of carbon core, and the expansion-buffering capability of the porous carbon shell, achieving synergistic effects that resolve the contradiction between capacity and volume management.
2Quantity of substance
If mesoporous carbon coating is applied to Sn anode, then capacity is enhanced, but initial charge-discharge efficiency is relatively low
Solution Approach 1:
The patent applies parameter changes by optimizing the porosity (greater than 10%) and pore size (50-200 nm) of the carbon shell, as well as the composition ratios of Co and Sn elements in the shell. These parameter optimizations balance the trade-off between capacity enhancement and charge-discharge efficiency by ensuring adequate ion transport pathways while maintaining sufficient active material content.
Solution Approach 2:
The patent implements local quality by creating a porous carbon shell with specific local properties (porosity, pore size, elemental distribution) that differ from the dense core structure. The porous region provides optimized pathways for ion transport and expansion accommodation, while the core provides structural stability, achieving localized functional optimization that resolves the efficiency-capacity contradiction.
3Stability of the object's composition
If conventional carbon coating is used on Sn anode, then structure stability is improved, but porosity is insufficient to prevent volume expansion during cycling
Solution Approach 1:
The patent applies porous materials by designing a carbon shell with controlled porosity (greater than 10%) and pore size (50-200 nm) that provides sufficient void space to accommodate the volume expansion of Sn during lithiation. The porous structure acts as a buffer that absorbs expansion stress while maintaining structural integrity and preventing particle disintegration during cycling.
Solution Approach 2:
The patent implements preliminary action by pre-construcing a porous carbon shell with adequate void space before the volume expansion occurs during battery cycling. This pre-designed porous structure anticipates and accommodates the expansion of Sn, preventing structural failure before it happens and maintaining long-term stability.
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 porous core-shell structure prevents volume expansion during charging and discharging, enhancing the electrical cycle performance and specific capacity of the battery, with a retention rate of over 79% after 50 cycles.
Implementation Method 1
the carbon shell contains amorphous carbon, cobalt element and tin element, and has a porous structure having a porosity greater than 10%
Implementation Method 2
subjecting the second solid phase to a high temperature decomposition treatment in inert atmosphere
Data Source
AI summary
The present disclosure relates to an anode material having porous core-shell structure, the anode material includes a core formed of at least one carbonaceous material selected from a group consisting of graphite, hard carbon and soft carbon, and a carbon shell coated on a surface of the core. The carbon shell contains amorphous carbon, cobalt element and tin element, and has a porous structure having a porosity greater than 10%. The present disclosure further relates to a method of preparing the anode material having porous core-shell structure, and a battery of which a negative electrode contains the anode material having porous core-shell structure.