Can Cell Formation With Strain-Absorbing Layers for Silicon Anodes
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Solution Overview
Problem
Conventional methods for forming can cells are costly, cumbersome, and inefficient, limiting battery lifetime and performance, particularly for silicon-dominant anodes which experience significant volume changes during charge-discharge cycles.
Innovation Solution
The use of strain absorbing materials, such as foam or gel polymer electrolytes, within the can cells to manage pressure and expansion during formation and operation, combined with a lamination or direct coating process that incorporates silicon-dominant anodes and cathodes with conductive additives, to enhance electrical contact and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional formation methods are used for can cells, then the process is simple, but the battery lifetime is limited and performance is reduced
Solution Approach 1:
The patent applies preliminary action by performing formation cycles at elevated temperatures (40-80°C) before normal operation. This pre-treatment creates stable SEI layers and activates lithium inventory in advance, improving battery lifetime and performance without adding complexity to the overall manufacturing process.
Solution Approach 2:
The patent changes operational parameters by conducting formation at elevated temperatures (40-80°C) compared to conventional room temperature formation. This parameter change accelerates SEI formation, improves lithium inventory activation, and enhances overall battery performance and lifetime.
2Quantity of substance
If silicon-dominant anodes are used to increase energy density, then energy density improves, but volume changes during charge-discharge cause expansion and performance degradation
Solution Approach 1:
The patent changes the temperature parameter during formation (40-80°C) to accommodate silicon anode expansion. The elevated temperature facilitates more flexible SEI formation that can accommodate volume changes, maintaining structural stability while preserving the high energy density benefits of silicon-dominant anodes.
Solution Approach 2:
The patent applies beforehand cushioning by creating a robust, flexible SEI layer during elevated temperature formation that anticipates and accommodates future silicon expansion. This pre-formed protective layer prevents structural degradation during subsequent charge-discharge cycles.
3Productivity
If formation is performed at room temperature, then energy consumption is low, but SEI formation is slow and lithium inventory activation is insufficient
Solution Approach 1:
The patent changes the temperature parameter from room temperature to elevated temperatures (40-80°C) during formation. This parameter change accelerates SEI formation kinetics and improves lithium inventory activation, significantly enhancing productivity despite increased energy consumption.
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 approach increases the performance and cycle life of silicon-dominant anode cells by maintaining electrical contact and reducing impedance, while the strain absorbing materials ensure uniform pressure and prevent bulging, leading to improved energy density and safety in lithium-ion batteries.
Implementation Method 1
one or more strain absorbing materials may be arranged between the one or more cells and interior walls of the can
Implementation Method 2
The strain absorbing materials may comprise foam
Data Source
AI summary
A method for formation of cylindrical and prismatic can cells may include providing a battery, where the battery includes one or more cells, with each cell including at least one silicon-dominant anode, a cathode, and a separator. The battery also includes a metal can that contains the one or more cells such that during formation a pressure between 50 kPa and 1 MPa is applied to the one or more cells. The battery may include strain absorbing materials arranged between the one or more cells and interior walls of the can. The strain absorbing materials may include foam. The strain absorbing materials may include a solid electrolyte layer. The strain absorbing materials may include PMMA, PVDF, or a combination thereof. The pressure during a formation process may be due to a thickness of the strain absorbing materials being thicker than an expansion of the one or more cells.