Porous Silicon Anode Composition for Stable High-Capacity Cycling
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Solution Overview
Problem
Secondary batteries using silicon-based materials face issues with high volume expansion, poor cycle performance, and low First Coulombic Efficiency due to the large volume effect of silicon, leading to particle breakage and pulverization, which limits their energy density and lifespan.
Innovation Solution
A negative electrode active material is developed with a matrix material having pore structures, where crystalline silicon-based material is mainly located in the inner region and amorphous silicon-based material in the outer region, with a coating layer to prevent direct contact with the electrolyte, reducing volume expansion and improving conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative electrode active material, then capacity is improved, but volume expansion occurs leading to particle breakage and pulverization
Solution Approach 1:
The patent employs a porous matrix material as the negative electrode active material. The porous structure provides internal void space that can accommodate the volume expansion of silicon-based materials during lithiation, preventing particle breakage and pulverization while maintaining structural integrity. The pores act as buffers that absorb expansion stresses without compromising the overall particle structure.
Solution Approach 2:
The patent creates a composite material system where silicon-based material is integrated within a porous matrix material. This composite structure combines the high capacity advantage of silicon with the structural stability of the matrix material. The matrix material provides a stable framework that constrains silicon expansion, while silicon contributes high lithium storage capacity, achieving both high capacity and particle integrity.
2Quantity of substance
If silicon-based material is used as negative electrode active material, then energy density is improved, but cycle performance deteriorates due to volume expansion
Solution Approach 1:
The porous matrix material provides a stable, reversible structure that maintains integrity during repeated charge-discharge cycles. The porous architecture allows for controlled ion transport and accommodates volume changes without structural collapse, enabling long cycle life. The matrix material's structural stability ensures consistent performance over many cycles while maintaining high energy density from the silicon content.
3Quantity of substance
If silicon-based material is used as negative electrode active material, then capacity is improved, but First Coulombic Efficiency deteriorates due to particle breakage
Solution Approach 1:
The porous matrix material prevents particle breakage and pulverization during initial charging cycles. By maintaining particle integrity, the porous structure ensures that more of the active material remains electrochemically active and accessible, leading to higher First Coulombic Efficiency. The stable porous framework prevents the formation of isolated, inactive fragments that would reduce efficiency.
4Volume of stationary object
If silicon-based material is used as negative electrode active material, then volume expansion occurs, but structural stability is required
Solution Approach 1:
The porous matrix material is specifically designed with sufficient porosity to accommodate the volume expansion of silicon-based material during lithiation. The pore spaces act as internal reservoirs that absorb expansion without generating damaging stresses. This allows the material to undergo volume changes while maintaining overall structural stability and preventing particle disintegration.
Solution Approach 2:
The composite structure combines silicon-based material with a porous matrix material that provides structural stability. The matrix material forms a stable framework that constrains and guides the expansion of silicon, distributing stresses uniformly. This composite approach allows volume expansion to occur in a controlled manner while maintaining structural integrity throughout the charge-discharge process.
Data Source
AI summary
The present application provides a negative electrode active material, a secondary battery comprising the same and an electrical device, wherein the negative electrode active material comprises a matrix material and a silicon-based material, the matrix material comprises a plurality of pore structures, at least a part of the silicon-based material is located in pore structures of the matrix material, the silicon-based material comprises a crystalline silicon-based material, a region formed by extending from outer surface of particle of the negative electrode active material to inside of the particle by a distance of 0.5 times a length between any point on the outer surface of the particle of the negative electrode active material and a core of the particle is recorded as an outer region, and a region inside the outer region is recorded as an inner region.