Bipolar Battery Assembly Optical Welding for High-Density Stacks
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Solution Overview
Problem
Monopolar lead acid batteries have lower energy densities, poor cycling performance under high-current-rate or deep discharge conditions, and high self-discharge rates compared to other chemistries, due to the limitations of lead alloy grids and materials used.
Innovation Solution
The development of a bipolar battery architecture with a conductive substrate providing inter-cell electrical connections, where biplate assemblies are compressed and welded using optical or hot-plate welding techniques to form a unitized assembly, enhancing energy storage capacity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If monopolar lead acid battery architecture is used, then manufacturing simplicity is maintained, but energy density is reduced
Solution Approach 1:
The battery is divided into multiple bipolar plates stacked in series, with each plate containing both positive and negative active materials on opposite sides. This segmentation allows current to flow perpendicular to the plate surfaces, effectively doubling the energy storage capacity per unit volume compared to traditional monopolar designs while maintaining a straightforward stacking manufacturing process.
Solution Approach 2:
The patent transitions from the traditional planar monopolar configuration to a three-dimensional bipolar stack arrangement. Current flow is redirected from parallel to perpendicular relative to the plate surfaces, utilizing the vertical dimension more effectively. This dimensional change enables higher energy density without complicating the basic manufacturing approach.
2Device complexity
If monopolar lead acid battery architecture is used, then structural simplicity is maintained, but cycling performance under high-current-rate conditions deteriorates
Solution Approach 1:
By segmenting the battery into multiple bipolar plates connected in series, the internal resistance is distributed across multiple interfaces. This segmentation reduces the current density at each individual plate interface, improving cycling performance under high-current-rate conditions while maintaining overall structural simplicity through repetitive stacking.
Solution Approach 2:
The bipolar design merges the positive and negative current collectors into a single conductive substrate that serves both functions. This merging eliminates the need for separate current collectors and reduces the number of connection points, simplifying the overall structure while enhancing electrical performance and cycling reliability.
3Device complexity
If monopolar lead acid battery architecture is used, then material usage is simplified, but self-discharge rate increases
Solution Approach 1:
The bipolar architecture merges the current collector function into the active material substrate itself, eliminating separate current collector materials. This reduction in material interfaces and simplification of material usage directly reduces galvanic corrosion and parasitic reactions, thereby lowering the self-discharge rate compared to traditional monopolar designs.
4Quantity of substance
If bipolar battery architecture is implemented, then energy storage capacity is improved, but manufacturing complexity increases
Solution Approach 1:
The bipolar battery is manufactured by segmenting it into identical or modular bipolar plate units that can be produced using standardized processes. Each plate is stacked in sequence with separators and compressive force applied uniformly. This segmentation strategy enables high energy storage capacity while keeping manufacturing complexity manageable through repetition and standardization.
5Reliability
If bipolar battery architecture is implemented, then cycling performance is improved, but device complexity increases
Solution Approach 1:
The bipolar design merges multiple functions into the single conductive substrate, which serves as both the current collector and the structural backbone. This functional merging improves cycling performance by reducing interface resistance and contact losses, while the integrated design actually simplifies the overall device architecture compared to the multiple separate components required in monopolar systems.
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 bipolar configuration improves energy storage capacity, reduces gas evolution, and maintains compression, leading to enhanced cycling performance and reduced self-discharge rates, addressing the limitations of monopolar lead acid batteries.
Implementation Method 1
irradiating an optically-absorbing region of the first casing portion through an optically-transmissive portion of the second casing portion
Implementation Method 2
irradiating an optically-absorbing region of the first casing portion through an optically-transmissive portion of the second casing portion to form a weld structure
Implementation Method 3
The irradiating can include using a laser to thermally form the weld structure
Implementation Method 4
compressing the stack of biplate assemblies
Implementation Method 5
irradiating an optically-absorbing region of the first casing portion through an optically-transmissive portion of the second casing portion to form a weld structure along at least one edge of the second casing portion
Data Source
AI summary
A battery assembly, such as a bipolar battery assembly can be fabricated using an optical welding process. For example, a stack of biplate assemblies can be assembled including aligning the biplate assemblies using a fixture, the fixture having at least one feature sized and shaped to engage a corresponding feature in a first casing portion in the stack of biplate assemblies. The stack of biplate assemblies can be compressed. A second casing portion comprising an optically-transmissive region can be mated to the first casing portion. An optically-absorbing region of the first casing portion can be irradiated through an optically-transmissive portion of the second casing portion to form a weld structure along at least one edge of the second casing portion.