Silicon Electrode Layer Binder Layout for Low Resistance Growth
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Solution Overview
Problem
The large volume change of silicon (Si) electrode active materials during charge and discharge leads to increased battery resistance due to peeling off of the electrode active material and other substances, which affects the battery's performance and energy density.
Innovation Solution
An electrode layer comprising a silicon element with a binder containing unsaturated bonds, where the overlapping degree of Si and Os elements is within a specific range, and includes a solvent component and solid electrolyte with specific Hansen solubility parameters, enhancing the adhesion and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a Si element is used as an electrode active material, then the theoretical capacity and energy density are improved, but the volume change during charge and discharge increases causing peeling off and resistance increase
Solution Approach 1:
The binder with unsaturated bonds performs preliminary action by selectively locating around the Si electrode active material before charge-discharge cycles begin. This pre-positioning ensures that when volume expansion occurs during lithiation, the binder is already in place to provide mechanical support and prevent peeling off, thus maintaining resistance stability while allowing high theoretical capacity utilization
Solution Approach 2:
The binder acts as an intermediary between the Si electrode active material and other substances (solid electrolyte, conductive material). It mediates the mechanical stress during volume change, preventing direct contact loss and peeling off between the Si particles and surrounding materials, thereby maintaining reliable electrical contact and resistance stability
2Quantity of substance
If the volume change of Si is large during charge and discharge, then the capacity is improved, but the electrode active material and other substances easily peel off
Solution Approach 1:
The binder exhibits local quality by selectively locating around the Si electrode active material rather than being uniformly distributed. This localized concentration of binder with unsaturated bonds provides enhanced adhesion strength precisely where the volume change occurs, maintaining strong bonding between the electrode active material and other substances during capacity-cycling operations
Solution Approach 2:
The electrode layer forms a composite material system combining Si electrode active material with binder containing unsaturated bonds. This composite structure leverages the high capacity of Si while the binder component provides mechanical flexibility and adhesion, creating a composite that accommodates volume change without peeling off
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 electrode layer exhibits reduced resistance increase during charge and discharge, maintaining high energy density by preventing the peeling off of electrode active material and other substances, thus improving battery performance.
Implementation Method 1
when the binder is dyed by Os dyeing and then an overlapping degree D of the Si element and the Os element is calculated based on an element mapping image obtained by a SEM-EDX measurement
Data Source
Figure 1~3B
Figure 4~5C
AI summary
A main object of the present disclosure is to provide an electrode layer of which resistance increase due to charge and discharge is little. The present disclosure achieves the object by providing an electrode layer including an electrode active material including a Si element, and a binder including an unsaturated bond, wherein when the binder is dyed by Os dyeing and then an overlapping degree D of the Si element and the Os element is calculated based on an element mapping image obtained by a SEM-EDX measurement, the D is larger than 0.047.