Silicon-Carbon Anode Skeleton Structure for Low-Expansion Li-Ion Batteries
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Solution Overview
Problem
Silicon anode materials for lithium batteries face challenges due to low electrical conductivity, significant volume expansion, and poor cycling stability, which limits their capacity and lifespan, while silicon-carbon composite materials often compromise on efficiency.
Innovation Solution
An anode material comprising a composite structure with LixMySiO4 as the first skeleton and carbon as the second skeleton, where nano-silicon is distributed within or on the LixMySiO4, and a carbon coating layer is applied to enhance conductivity and stability, with specific ratios and structures to control volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon material is used as anode material to achieve high theoretical capacity, then the capacity is improved, but the volume expansion is significant and cycling stability deteriorates
Solution Approach 1:
The patent embeds silicon particles inside a porous carbon matrix structure, creating a nested configuration where silicon is contained within carbon. This nesting approach allows silicon to expand and contract during cycling without compromising the overall structural integrity, as the porous carbon framework provides a buffer that accommodates volume changes while maintaining electrical conductivity and mechanical stability.
Solution Approach 2:
The patent creates a composite material system combining silicon particles with porous carbon matrix. This composite structure leverages the high capacity of silicon while utilizing the structural stability and conductivity of carbon to mitigate silicon's drawbacks. The composite design enables both materials to contribute their advantageous properties, achieving high capacity with improved cycling stability.
2Quantity of substance
If silicon material is used to achieve high theoretical capacity, then the capacity is improved, but the electrical conductivity is low
Solution Approach 1:
The patent creates a composite material system combining silicon particles with porous carbon matrix. This composite structure leverages the high capacity of silicon while utilizing the structural stability and conductivity of carbon to mitigate silicon's drawbacks. The composite design enables both materials to contribute their advantageous properties, achieving high capacity with improved cycling stability.
Solution Approach 2:
The porous carbon matrix acts as an intermediary between silicon particles and the electrolyte, facilitating electron transport and maintaining electrical conductivity. The carbon framework provides conductive pathways that connect silicon particles to the current collector, ensuring efficient electron transfer while allowing ionic transport through the porous structure.
3Quantity of substance
If silicon material is used to achieve high theoretical capacity, then the capacity is improved, but the volume expansion causes SEI film rupture and further degradation
Solution Approach 1:
The patent embeds silicon particles inside a porous carbon matrix structure, creating a nested configuration where silicon is contained within carbon. This nesting approach allows silicon to expand and contract during cycling without compromising the overall structural integrity, as the porous carbon framework provides a buffer that accommodates volume changes while maintaining electrical conductivity and mechanical stability.
Solution Approach 2:
The porous carbon matrix serves as a pre-designed cushioning structure that anticipates and accommodates the volume expansion of silicon during lithiation. The porous framework provides extra space and mechanical compliance before expansion occurs, preventing stress concentration that would lead to SEI film rupture and particle pulverization.
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 proposed anode material exhibits improved electrical conductivity, reduced volume expansion, higher efficiency, and extended cycle life, effectively addressing the limitations of silicon-based anodes.
Implementation Method 1
nano-silicon is distributed in the LixMySiO4 material or/and on a surface of the LixMySiO4 material
Implementation Method 2
a carbon coating layer is applied to enhance conductivity and stability
Implementation Method 3
M includes a metal element capable of reducing silicon oxides
Data Source
AI summary
The present disclosure relates to an anode material, a method for preparing the same, and a lithium ion battery, which belong to the technical field of energy storage materials. The anode material includes a LixMySiO4 material, a carbon material and nano-silicon. The LixMySiO4 material and the carbon material has a network structure, independently forming a first skeleton and a second skeleton in the anode material respectively. The first skeleton and the second skeleton are entangled with each other, and the nano-silicon is distributed in the matrix or/and on the surface of LixMySiO4 material. In the LixMySiO4 material, the values of x and y satisfy charge balance, and M includes a metal element capable of reducing silicon oxides, the metal element excludes Li. The anode material has better electrical conductivity, more stable structure, lower volume expansion, higher electrical conductivity, higher first efficiency and excellent rate performance.