Can Cell Formation With Strain-Absorbing Layers for Silicon Anode Expansion
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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 elastic layers, within the can cells to manage pressure and expansion during formation and cycling, combined with advanced lamination and direct coating processes for silicon-dominant anode cells, ensures uniform pressure and increased cell life.
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 poor
Solution Approach 1:
The patent applies preliminary action by performing formation cycles at elevated temperatures (45°C to 65°C) before normal operation. This pre-treatment process prepares the silicon-dominant anode by controlling volume changes and SEI layer formation in advance, improving battery lifetime and performance without adding complex formation equipment
Solution Approach 2:
The patent changes physical parameters by conducting formation at elevated temperatures (45°C to 65°C) and controlling charge-discharge rates (0.1C to 1C). These parameter modifications optimize the formation process to prevent silicon anode degradation and improve battery reliability without increasing device complexity
2Productivity
If conventional formation methods are used for can cells, then the process is straightforward, but the formation time is long and efficiency is low
Solution Approach 1:
The patent applies periodic action by using controlled charge-discharge cycles during formation. Multiple cycles at optimized rates (0.1C to 1C) and temperatures (45°C to 65°C) efficiently complete the formation process, reducing formation time while maintaining high productivity through systematic periodic treatment
Solution Approach 2:
The patent changes operational parameters by conducting formation at elevated temperatures (45°C to 65°C) and optimized charge-discharge rates (0.1C to 1C). These parameter changes accelerate the formation process, reducing formation time from conventional extended periods to optimized cycles, thereby improving productivity
3Quantity of substance
If silicon-dominant anodes are used, then energy density is high, but volume changes during cycling cause capacity loss and cell bulging
Solution Approach 1:
The patent applies beforehand cushioning by providing a can design with sufficient internal volume and strategic placement of components to accommodate silicon anode expansion (up to 300%). The can structure includes space for electrolyte and components positioned to prevent bulging, cushioning against volume changes before they occur during cycling
Solution Approach 2:
The patent changes the charge-discharge rate parameter (0.1C to 1C) and temperature (45°C to 65°C) to control the rate and magnitude of silicon anode volume changes. These parameter modifications reduce mechanical stress and prevent capacity loss while maintaining high energy density, stabilizing the cell structure during cycling
4Manufacturing precision
If pressure is applied during formation, then uniform pressure distribution is achieved, but the process becomes more complex
Solution Approach 1:
The patent uses the can structure itself as an intermediary to distribute pressure uniformly during formation. The can acts as a pressure-distributing medium, eliminating the need for complex external pressure application systems while achieving uniform pressure distribution across the cell components through its inherent structural properties
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 enhances the performance and longevity of silicon-dominant anode cells by maintaining electrical contact and preventing capacity loss due to volume changes, while reducing formation time and eliminating bulging issues, thereby improving energy density and cycle life.
Implementation Method 1
one or more strain absorbing materials may be provided between the one or more cells and interior walls of the can. The strain absorbing materials may comprise foam. The strain absorbing materials may comprise a solid electrolyte layer.
Implementation Method 2
The known expansion of the cell stack along with the strain absorbing material within may enable a desired pressure or pressure range on the electrodes during formation
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.