Silicon-Carbon Anode Structure for Battery Cycle Retention
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Solution Overview
Problem
Secondary batteries with high-capacity electrode materials suffer from poor cycle performance due to significant volume changes during charge and discharge, leading to increased internal resistance and reduced capacity retention.
Innovation Solution
A secondary battery design incorporating a silicon-carbon composite material with a three-dimensional network cross-linked pore structure and an electrolyte solution containing a cyclic carbonate compound, which forms a stable interface film to reduce internal resistance and enhance cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity electrode material is used, then energy density is improved, but cycle performance deteriorates due to volume changes
Solution Approach 1:
The patent employs a porous carbon material as the negative electrode active material, utilizing its porous structure to accommodate volume changes during charge-discharge cycles. The porous structure provides expansion space for the high-capacity electrode material, reducing mechanical stress and maintaining structural integrity over multiple cycles, thus improving cycle performance while preserving high energy density.
Solution Approach 2:
The patent uses a composite structure combining porous carbon material with high-capacity electrode material. This composite approach allows the carbon matrix to provide structural stability and accommodate volume changes, while the high-capacity material delivers superior energy density, resolving the contradiction between capacity and cycle life.
2Quantity of substance
If silicon content is increased, then gram capacity is improved, but volume change increases leading to poor cycle performance
Solution Approach 1:
The porous carbon material provides a three-dimensional network structure with abundant pores that can accommodate the significant volume expansion of silicon during lithiation. The porous structure acts as a buffer, allowing silicon to expand and contract without experiencing the mechanical stress that would otherwise lead to pulverization and poor cycle performance, thereby enabling high silicon content while maintaining structural integrity.
Solution Approach 2:
The patent utilizes the local porous structure of the carbon material to accommodate silicon volume changes. The pores are strategically distributed throughout the carbon matrix, providing localized expansion spaces near silicon particles, allowing each region to independently accommodate volume changes without affecting the overall structural stability.
3Stability of the object's composition
If electrolyte solution is optimized, then interface stability is improved, but internal resistance increases
Solution Approach 1:
The patent optimizes the electrolyte solution composition by adjusting the proportions of different carbonate solvents and lithium salt concentration. This parameter optimization allows the formation of a stable solid electrolyte interface (SEI) film on the porous carbon electrode, reducing continuous decomposition reactions. The optimized electrolyte parameters enable interface stability while maintaining sufficiently low internal resistance for practical battery operation.
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 combination of the silicon-carbon composite material and cyclic carbonate compound improves cycle capacity retention, reduces gas generation, and enhances energy density by stabilizing the interface and maintaining mechanical strength.
Implementation Method 1
the cyclic carbonate compound coordinated in the electrolyte solution can be used to construct an interface component on the surface of the silicon-carbon composite material to form a stable interface film
Implementation Method 2
The silicon-carbon composite material having a three-dimensional network cross-linked pore structure has a stable porous framework and good mechanical strength, and can effectively reduce the volume change of silicon before and after charging and discharging
Data Source
AI summary
A secondary battery. The secondary battery includes a negative electrode plate and an electrolyte solution. The negative electrode plate of the secondary battery includes a silicon-carbon composite material having a three-dimensional network cross-linked pore structure; and the electrolyte solution of the secondary battery includes a cyclic carbonate compound shown in formula I.