Silicon Negative Electrode Sheet With Vertical Through Holes
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Solution Overview
Problem
The charging capacity of silicon negative electrode lithium ion batteries needs to be improved to meet the increasing demand for long battery life in electric vehicles and consumer goods, as existing technologies do not effectively enhance energy density and ion transmission efficiency.
Innovation Solution
A silicon negative electrode sheet with a current collector and multiple active coating layers containing silicon materials, where through holes are formed vertically and arranged at intervals, with varying silicon content and a staggered hole arrangement, improving porosity and ion transmission, and incorporating graphite materials for enhanced conductivity and volume expansion management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon content in active coating layers is increased to improve energy density, then charging capacity is improved, but volume expansion strain and structural stability deteriorate
Solution Approach 1:
The negative electrode sheet is divided into multiple active coating layers with different silicon contents. The first active coating layer (proximal to current collector) has higher silicon content (5-30 wt%) to provide high charging capacity, while the second active coating layer (distal from current collector) has lower silicon content (0-5 wt%) to reduce expansion strain. This segmentation allows the electrode to achieve high overall capacity while the low-silicon outer layer protects the structure from excessive expansion damage.
2Speed
If porosity is increased to improve ion transmission, then ion transmission efficiency is improved, but mechanical strength deteriorates
Solution Approach 1:
Different regions of the active coating layers have different porosity characteristics. The through holes are specifically arranged to create localized high-porosity channels for efficient ion transmission, while the matrix structure maintains adequate mechanical strength. The porosity is optimized locally in the regions where ion transmission is most critical, rather than uniformly throughout the entire electrode structure.
Solution Approach 2:
The active coating layers are composed of composite materials including silicon-based negative active materials, conductive agents, and bonding agents. This composite structure allows the electrode to simultaneously achieve high porosity for ion transmission and sufficient mechanical strength, as each component contributes different properties to the overall structure.
3Ease of manufacture
If uniform silicon content is used throughout the electrode to simplify manufacturing, then manufacturing complexity is reduced, but charging uniformity deteriorates
Solution Approach 1:
The electrode structure employs local quality variation with different silicon contents in different layers. The first active coating layer has higher silicon content optimized for high capacity regions, while the second active coating layer has lower silicon content optimized for structural stability regions. This gradient structure ensures uniform charging performance across the entire electrode by matching silicon content to local functional requirements.
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 improved porosity and ion transmission distance reduce the strain on silicon particles, enhancing the charging capacity and liquid holding capacity of the battery, while the staggered hole arrangement and varying silicon content ensure uniform charging and discharging, thus improving the overall performance of the silicon negative electrode.
Implementation Method 1
the through holes extending vertically through the respective active coating layer wherein the through holes are arranged at intervals in the active coating layers
Implementation Method 2
The improved porosity and ion transmission distance reduce the strain on silicon particles, enhancing the charging capacity and liquid holding capacity of the battery
Implementation Method 3
there are gaps between silicon material particles of the silicon negative electrode sheet, which provides a buffer space for the cyclic expansion inside the silicon particles
Data Source
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Figure 3~5
AI summary
A silicon negative electrode sheet (100) including: a current collector (110); and at least two active coating layers (120) containing negative active materials, which are sequentially coated on the current collector (110). Through holes (130) are formed in the active coating layers (120) extending vertically through the respective active coating layer and being arranged at intervals. By the embodiment of the present invention, the liquid holding capacity of the silicon negative electrode sheet (100) and the charging capacity of a silicon negative electrode are improved.