Cation-Substituted Polycarboxylic Acid Interlayer for Silicon Anodes
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Solution Overview
Problem
Graphite-based negative electrodes for secondary batteries have low theoretical capacity and suffer from rapid volume changes in silicon-based materials, leading to side reactions and detachment of the active material, which deteriorate battery performance.
Innovation Solution
A negative electrode with an interlayer composed of cation-substituted polycarboxylic acid or its copolymer on the current collector, enhancing adhesion between the current collector and the active material layer, reducing interfacial resistance, and improving mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based material is used as the negative electrode active material to increase theoretical capacity, then the battery capacity is improved, but the rapid volume change causes side reactions, detachment of active material, and loss of SEI layer, leading to deterioration of battery performance
Solution Approach 1:
The negative electrode is segmented into multiple functional layers: a current collector, an interlayer (comprising a first polymer layer and optionally a second polymer layer), and an active material layer. This segmentation allows the interlayer to specifically address the volume expansion issue of silicon-based materials while the active material layer maintains high capacity, thus resolving the contradiction between capacity and reliability.
Solution Approach 2:
An interlayer comprising polymer(s) is introduced as an intermediary between the current collector and the silicon-based active material. This interlayer acts as a mediator that suppresses volume expansion of the silicon particles, reduces side reactions, and prevents detachment of the active material, thereby maintaining battery performance while enabling the use of high-capacity silicon-based materials.
2Stability of the object's composition
If the amount of binder is increased to suppress volume expansion of silicon-based material, then the mechanical stability is improved, but the interfacial adhesion characteristics between current collector and active material layer weaken
Solution Approach 1:
The interlayer comprising polymer(s) serves as an intermediary that provides both mechanical stability through volume expansion suppression and strong interfacial adhesion. The polymer molecules form a bridging layer that adheres to both the current collector and the active material particles, eliminating the need to increase binder amount while maintaining both mechanical stability and interfacial strength.
Solution Approach 2:
The invention changes the chemical and physical parameters of the interface between current collector and active material by introducing a polymer-based interlayer. This interlayer has specific molecular structures (carboxyl groups, cation-substituted groups) that provide both adhesion to the current collector and compatibility with silicon-based active material, thereby achieving strong interfacial bonding without compromising mechanical stability.
3Reliability
If a graphite-based negative electrode is used to maintain excellent lifetime and voltage characteristics, then the battery reliability is improved, but the theoretical capacity is low
Solution Approach 1:
The negative electrode uses a composite structure combining silicon-based active material (for high capacity) with polymer-based interlayer materials (for stability). This composite approach allows the system to achieve both high theoretical capacity from silicon and excellent lifetime characteristics from the stable polymer matrix, resolving the contradiction between capacity and reliability.
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 improves the initial efficiency and capacity retention of secondary batteries by preventing detachment of the active material during volume expansion, leading to enhanced battery performance and lifetime characteristics.
Implementation Method 1
an interlayer on the current collector and consisting of at least one first polymer selected from cation-substituted polycarboxylic acid and a copolymer thereof
Implementation Method 2
cation-substituted polycarboxylic acid
Implementation Method 3
reducing interfacial resistance
Data Source
AI summary
A negative electrode for a secondary battery, the negative electrode including: a current collector; an interlayer on the current collector and consisting of at least one first polymer selected from a cation-substituted polycarboxylic acid and a copolymer thereof; a negative electrode active material layer on the interlayer and which includes a negative electrode active material and a binder.