Silicon Anode Composite with Porous Carbon Shell for Volume Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion battery negative electrodes made from silicon face challenges such as volume expansion and contraction, leading to structural instability and reduced electrochemical performance due to the risk of particle breakage and SEI film thickening, which affects their cycling and rate performance.
Innovation Solution
A silicon-based negative electrode composite material is developed by doping silicon with zinc and tin, and coating it with a carbon shell to enhance conductivity and structural stability, using a method involving spray drying, liquid phase coating, and reduction-sintering to create a symmetrical conductive structure that alleviates volume effects and improves ion and electronic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode material is used to achieve high specific capacity, then the theoretical specific capacity can reach 4200 mAh/g, but volume expansion and contraction during charging and discharging cause particle breakage, separation from the electrode plate, and SEI film thickening, which seriously affects electrochemical performance and structural stability
Solution Approach 1:
The patent embeds silicon particles within a porous carbon matrix structure, creating a nested configuration where silicon is contained inside the carbon framework. This nesting approach allows silicon to expand and contract within the confined porous space of the carbon matrix, preventing particle breakage and maintaining structural stability while preserving high specific capacity
Solution Approach 2:
The patent employs a porous carbon matrix with controlled pore structures to accommodate silicon volume changes. The porous structure provides expansion space for silicon during lithiation, prevents particle aggregation and breakage, and maintains electrical conductivity throughout the electrode, thereby resolving the contradiction between high capacity and structural stability
2Quantity of substance
If silicon material undergoes volume expansion and contraction during charging and discharging, then high capacity is achieved, but the huge volume effect easily causes particle breakage and separation from the electrode plate, affecting cycling performance
Solution Approach 1:
The patent utilizes a flexible porous carbon matrix that can dynamically accommodate silicon volume changes during cycling. The carbon matrix acts as a flexible container that expands and contracts with silicon, preventing particle breakage and maintaining electrical contact, thereby extending cycle life while preserving high capacity
Solution Approach 2:
The patent creates a composite material system combining silicon with porous carbon matrix. The composite structure leverages the high capacity of silicon and the structural stability and conductivity of carbon, achieving both high capacity and long cycle life through synergistic material combination
3Productivity
If silicon surface is exposed during charging and discharging, then electrochemical activity is enhanced, but SEI film thickening occurs which affects rate performance and increases irreversible capacity loss
Solution Approach 1:
The patent creates a localized structure where silicon surfaces are confined within the porous carbon matrix, providing different functional zones: the inner region maintains high electrochemical activity through silicon exposure, while the outer porous carbon region provides protective pathways for ion transport and prevents uncontrolled SEI formation, thereby reducing irreversible capacity loss
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 composite material achieves improved cycle stability, rate performance, and reduced irreversible capacity loss by minimizing silicon surface exposure and suppressing side reactions, resulting in enhanced lithium-ion battery performance with fast charging capacity and optimal SEI film formation.
Implementation Method 1
preparing carbon balls through a spray drying treatment
Implementation Method 2
obtaining hollow spherical tin oxide/zinc oxide composite material after an oxidation-sintering treatment
Implementation Method 3
obtaining hollow spherical tin oxide/zinc oxide composite material after an oxidation-sintering treatment
Implementation Method 4
obtaining a precursor material after a reduction-sintering treatment
Implementation Method 5
obtaining a precursor material after a reduction-sintering treatment
Implementation Method 6
introducing a silicon source, depositing silicon into the interior of the precursor
Data Source
AI summary
A silicon-based negative electrode composite material. Zinc and tin are doped in a silicon-based negative electrode material. The presence of a tin and zinc alloy improves the conductivity of the silicon-based material, and a coated carbon shell has pores, facilitating the infiltration of an electrolyte while improving the ionic conductivity and electronic conductivity of the material, so that the rate performance of the composite material is enhanced.