Si-Carbon Anode Composition for Swelling-Resistant Cycle Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Si-based materials for negative electrodes in secondary batteries experience significant volume changes during charge and discharge, leading to safety issues due to swelling and deterioration of charge-discharge cycle characteristics.
Innovation Solution
Incorporating a Si-based material and a conductive agent into the pores of activated carbon, which supports the Si-based material and maintains conductivity, thereby minimizing swelling and improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si-based material is used as negative electrode active material, then lithium ion occlusion capacity per unit volume is improved, but volume change during charge and discharge causes negative electrode swelling
Solution Approach 1:
The patent utilizes activated carbon with a porous structure as the negative electrode active material. The pores provide void space that accommodates the volume expansion of Si-based materials during lithium ion insertion, preventing macroscopic swelling of the electrode while maintaining high lithium ion occlusion capacity
Solution Approach 2:
The patent creates a composite material system consisting of Si-based materials dispersed within the porous activated carbon matrix. This composite structure combines the high lithium ion capacity of Si-based materials with the volume-buffering capability of the porous carbon structure, resolving the contradiction between capacity and volume stability
2Quantity of substance
If Si-based material is used as negative electrode active material, then lithium ion occlusion capacity is improved, but charge-discharge cycle characteristics deteriorate
Solution Approach 1:
The porous activated carbon structure provides a three-dimensional network that maintains structural integrity during cycling. The pores accommodate Si-based material expansion/contraction, preventing electrode disintegration and maintaining continuous electrical contact, thereby improving cycle life while preserving high lithium ion capacity
Solution Approach 2:
The activated carbon matrix acts as an intermediary that mediates between the Si-based material and the electrolyte. It provides a stable conductive network and physical confinement for the Si-based material, ensuring reliable electron transport and structural stability throughout charge-discharge cycles
3Volume of moving object
If Si-based material volume change is suppressed, then negative electrode swelling is reduced, but conductivity of negative electrode deteriorates
Solution Approach 1:
The porous activated carbon structure inherently provides conductive pathways through its carbon network. The pores are filled with conductive carbon material that maintains electrical connectivity even when accommodating Si-based material, thus preserving conductivity while managing volume changes
Solution Approach 2:
The composite of Si-based material and conductive carbon creates a synergistic structure where the carbon phase provides both volume accommodation and electrical conductivity. The conductive carbon network surrounds and connects Si-based particles, ensuring electron transport pathways are maintained despite Si volume changes during cycling
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
This configuration effectively suppresses negative electrode swelling and enhances the charge-discharge cycle characteristics of secondary batteries by managing volume changes and ensuring a conductive path for the Si-based material.
Implementation Method 1
Si-based materials are alloying materials to be alloyed with lithium. It is known that a Si-based material can occlude a larger amount of lithium ions per unit volume than a carbon-based active material such as graphite
Implementation Method 2
the volume change of the Si-based material caused by charge and discharge occurs in pores of the activated carbon, and therefore expansion of the Si-based material is less likely to lead to swelling of the negative electrode
Implementation Method 3
the conductive agent supported together with the Si-based material in pores of the activated carbon secures a conductive path of the Si-based material, and therefore deterioration of charge-discharge cycle characteristics of the battery is suppressed
Data Source
AI summary
Provided is a negative electrode active material for secondary batteries that is capable of inhibiting negative electrode swelling and the decline of the charge/discharge cycle characteristics of a battery. A negative electrode active material for secondary batteries according to the present disclosure is characterized by including a Si-based material, activated carbon, and a conductive material, and in that the Si-based material and the conductive material are carried in pores of the activated carbon.