Silicon-Composite Negative Electrode for Expansion Suppression
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Solution Overview
Problem
Lithium secondary batteries face challenges with silicon-based negative electrode materials due to high volume expansion and low charge/discharge efficiency, which limits their application in high-capacity batteries.
Innovation Solution
A negative electrode composition that includes a carbon-based active material, a silicon-based active material-polymer binder combination, and a water-based binder, where the polymer binder is adsorbed on the silicon-based active material to suppress expansion, and a conductive material is used to enhance charge/discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based active material is used as a negative electrode active material to achieve higher charge/discharge capacity, then the capacity is improved, but the electrode expansion rate becomes very high and charge/discharge efficiency becomes very low
Solution Approach 1:
A polymer binder is introduced as an intermediary substance that coats the surface of silicon-based active material particles. This polymer binder layer acts as a mediator that suppresses the expansion of silicon during lithium insertion, thereby maintaining structural integrity and improving charge/discharge efficiency while preserving the high capacity benefit of silicon-based materials
Solution Approach 2:
The negative electrode is designed as a composite structure combining silicon-based active material particles with a polymer binder coating. This composite material approach allows the electrode to benefit from both the high capacity of silicon and the structural stability provided by the polymer binder, resolving the contradiction between capacity and efficiency
2Quantity of substance
If a silicon-based active material is used to achieve higher charge/discharge capacity, then the capacity is improved, but the electrode expansion rate becomes very high
Solution Approach 1:
The polymer binder serves as an intermediary that physically constrains the silicon-based active material particles during lithium insertion. This intermediary layer suppresses the volume expansion of silicon by providing mechanical support and preventing uncontrolled expansion, thereby maintaining electrode structural integrity while enabling high capacity
Solution Approach 2:
A thin film of polymer binder is applied to the surface of silicon-based active material particles. This flexible thin film coating allows for some volume change accommodation while providing sufficient constraint to suppress excessive expansion, thereby maintaining both high capacity and structural stability
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 solution effectively suppresses volume expansion of the silicon-based active material, improves adhesion strength to the current collector, and enhances the lifespan and charge/discharge efficiency of the battery, maintaining a discharge capacity retention rate of 90% or greater up to the fifth cycle.
Implementation Method 1
a polymer binder bonded to a surface of the silicon-based active material, wherein the polymer binder suppresses expansion of the silicon-based active material
Implementation Method 2
materials capable of intercalating and deintercalating, or alloying and dealloying lithium ions are used as a negative electrode and a positive electrode
Implementation Method 3
electrical energy is generated by an oxidation reaction and a reduction reaction
Implementation Method 4
electrical energy is generated by an oxidation reaction and a reduction reaction
Data Source
AI summary
A negative electrode for a secondary battery, and more particularly, to a negative electrode for a secondary battery used for a negative electrode of a secondary battery. A negative electrode for a secondary battery may include a carbon-based active material; a conductive material; a silicon-based active material-polymer binder combination including a silicon-based active material, and a polymer binder bonded to a surface of the silicon-based active material, wherein the polymer binder suppresses expansion of the silicon-based active material; and a water-based binder.