Silicon Anode Tab Layout for Lower Impedance Battery Cells
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Solution Overview
Problem
Silicon-based materials in negative electrodes of electrochemical apparatuses suffer from low electrical conductivity and high-temperature expansion, leading to increased impedance, thermal runaway, and reduced cycle performance.
Innovation Solution
The negative tab is positioned on the side edge of the negative current collector, with a specific ratio of its distance to the active material layer length and silicon-based material content controlled to reduce impedance and temperature rise, enhancing the electrochemical apparatus's cycle performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used in negative electrode to replace graphite material, then theoretical gram capacity is improved, but electrical conductivity deteriorates and high-temperature expansion rate increases
Solution Approach 1:
The patent uses a composite structure where silicon-based material is combined with graphite material in the negative active material layer. This composite approach allows the silicon-based material to provide high theoretical gram capacity while graphite maintains electrical conductivity and structural stability, thereby resolving the contradiction between capacity improvement and conductivity deterioration.
2Quantity of substance
If silicon-based material is used in negative electrode to replace graphite material, then theoretical gram capacity is improved, but high-temperature expansion rate increases
Solution Approach 1:
The composite structure of silicon-based material and graphite material in the negative active material layer addresses the expansion issue. Graphite has low thermal expansion characteristics that constrain and stabilize the silicon-based material during high-temperature operation, reducing overall expansion rate while preserving the high capacity benefits of silicon.
Solution Approach 2:
The patent positions the negative tab at a specific location (side edge of the negative current collector) and controls the distribution of silicon-based material within the negative active material layer. This local optimization ensures that regions with silicon-based material are strategically placed to maximize capacity while minimizing expansion effects through proper spatial distribution.
3Reliability
If negative tab is positioned at specific location with controlled silicon-based material content, then impedance is reduced and temperature rise is controlled, but device structure becomes more complex
Solution Approach 1:
The patent optimizes specific parameters including the position of the negative tab (at the side edge of the current collector) and the weight percentage of silicon-based material (less than or equal to 70%). By carefully controlling these parameters, the patent achieves reduced impedance and controlled temperature rise without requiring fundamentally new structural concepts, thus limiting the increase in device complexity.
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
This configuration effectively reduces internal impedance, lowers temperature rise, and improves cycle performance and safety by optimizing current distribution and structural stability.
Implementation Method 1
The negative tab is arranged on a side edge of a long axis of the negative current collector and is in contact with the negative active material layer... effectively reduce the impedance of the negative electrode and control the temperature rise of a battery cell
Data Source
AI summary
An electrochemical apparatus includes a positive electrode, a separator and a negative electrode. The negative electrode includes a negative current collector, a negative active material layer and a negative tab, and the negative tab is arranged on a side edge of a long axis of the negative current collector and is in contact with the negative active material layer. The negative active material layer includes a silicon-based material, a distance between a central position of the negative tab and either end of the negative active material layer in a long axis direction is a first length, a length of a long axis of the negative active material layer is a second length, and 0.5≥D≥0.6×G, where D is a ratio of the first length to the second length, G is a weight percentage of the silicon-based material. The weight percentage of the silicon-based material is less than or equal to 70%.