Silicon Anode Electrode Plate With Fluorinated Skeleton Layer
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Solution Overview
Problem
Lithium-ion batteries using silicon-based negative electrodes face volume expansion issues during charging and discharging, leading to reduced cycling performance and capacity due to the pulverization and detachment of the active material layer.
Innovation Solution
An electrode plate design featuring a silicon-based active material layer with a skeleton layer rich in inert materials, such as fluorine, is introduced, which helps stabilize the solid electrolyte interface (SEI) film, preventing volume expansion and improving cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as active material to increase specific capacity, then battery energy density is improved, but volume expansion occurs during charging and discharging leading to pulverization and detachment of active material layer
Solution Approach 1:
The electrode plate is divided into multiple layers including a first active material layer containing silicon-based material, a protective layer, and a second active material layer. This segmentation isolates the silicon-based material that causes volume expansion, preventing it from damaging the overall electrode structure while still utilizing its high capacity benefits.
Solution Approach 2:
A protective layer is introduced as an intermediary between the silicon-based active material and the electrode plate structure. This protective layer acts as a buffer that accommodates volume expansion of the silicon-based material during charging and discharging, preventing pulverization and detachment while allowing lithium ion transport.
2Quantity of substance
If silicon-based material is used to achieve high specific capacity, then battery capacity is improved, but active material layer detaches from current collector reducing cycle life
Solution Approach 1:
The electrode plate is segmented into distinct layers with the silicon-based active material confined to a first active material layer. This segmentation prevents the detachment problem from affecting the entire electrode plate, isolating the issue to a manageable section while preserving the high capacity advantage.
Solution Approach 2:
The protective layer serves as an intermediary that bonds the silicon-based active material layer to the current collector, preventing detachment during cycling. This intermediary layer maintains electrical connection and structural integrity while accommodating the volume changes of the silicon-based material.
3Quantity of substance
If silicon-based material is used to improve energy density, then battery performance is enhanced, but SEI film is repeatedly grown and repaired consuming lithium source
Solution Approach 1:
By segmenting the electrode plate into a first active material layer with silicon-based material and other layers, the SEI film formation issue is confined to a specific region. This limits the amount of lithium consumed in SEI film repair cycles while preserving the high energy density benefits of silicon-based material.
Solution Approach 2:
The protective layer acts as an intermediary that stabilizes the interface between the silicon-based material and electrolyte, reducing the frequency and extent of SEI film breakdown and reformation. This intermediary layer provides a more stable environment that reduces lithium source consumption while maintaining the high capacity of silicon-based material.
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 skeleton layer enhances the stability of the SEI film, reducing lithium ion loss and improving the initial efficiency and cycle life of the battery by preventing active material layer pulverization and detachment.
Implementation Method 1
silicon particles are broken, a solid electrolyte interface (SEI) film is repeatedly grown, broken, and repaired
Implementation Method 2
a lithium intercalation reaction may occur after the electrode plate is immersed in an electrolyte solution
Data Source
AI summary
Disclosed are an electrode plate, a battery cell, and a battery. The electrode plate provided in the present disclosure includes a current collector and an active material layer disposed on at least one surface of the current collector. The active material layer includes active material, the active material includes a silicon-based material, a skeleton layer is provided outside the silicon-based material, and a proportion of a fluorine element gradually increases in a direction from the silicon-based material to the skeleton layer. The electrode plate, the battery cell, and the battery provided in the present disclosure are used to at least solve a technical problem that the battery is prone to volume expansion.