LFP Battery Module Assembly With Welded Collectors and BMS Sensing
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Solution Overview
Problem
Lead-acid batteries face issues such as antimony migration leading to reduced cycle life and safety concerns, while prismatic cells have short lifespans, are expensive, and lack flexibility in configuration, making them unsuitable for applications like 48V lithium batteries in golf cart sizes.
Innovation Solution
A lithium iron phosphate module with cylindrical cells and current collector plates connected via resistive welding, integrated with a battery management system for voltage monitoring and temperature sensing, allowing for flexible configurations and improved thermal management, using a five-layer clad material for current collection and quick disconnect tabs for easy assembly and monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If prismatic cells are used, then gas emission is eliminated and weight is reduced, but lifespan is shortened and thermal management becomes ineffective
Solution Approach 1:
The battery system is divided into modular prismatic cells that can be independently managed and replaced. Each cell is a self-contained unit with its own thermal and electrical characteristics, allowing for segmented thermal management and fault isolation, which extends overall system lifespan despite individual cell limitations.
2Object-generated harmful factors
If prismatic cells are used, then gas emission is eliminated, but the cell arrangement becomes fixed with no flexibility
Solution Approach 1:
The battery system is divided into modular prismatic cells that can be independently managed and replaced. Each cell is a self-contained unit with its own thermal and electrical characteristics, allowing for segmented thermal management and fault isolation, which extends overall system lifespan despite individual cell limitations.
Solution Approach 2:
The battery management system dynamically adjusts cell connections and configurations based on operational requirements. Cells can be reconfigured in different series/parallel arrangements to meet varying voltage and capacity demands, providing adaptability while maintaining the gas-free advantage of sealed prismatic cells.
3Strength
If antimony is added to electrode grids, then mechanical characteristics are improved, but antimony migration causes increased hydrogen evolution and capacity loss
Solution Approach 1:
The harmful antimony element is completely removed from the electrode grid composition. The patent uses pure lead or alternative alloys without antimony, eliminating the source of antimony migration that causes hydrogen evolution and capacity loss, thereby extending cycle life while maintaining structural integrity through different alloying strategies.
Solution Approach 2:
The electrode grids use composite material compositions that replace antimony with alternative alloying elements. These composite materials provide the necessary mechanical strength and durability without the harmful migration effects of antimony, resolving the contradiction between strength and reliability.
4Ease of operation
If ring lug with mechanical fasteners or soldered wire is used for voltage monitoring, then connection is established, but resistance to vibration and shock is insufficient
Solution Approach 1:
The patent replaces mechanical fastener connections and soldered wires with a direct integrated electrical connection system. Voltage monitoring contacts are directly mounted on the cell terminals or current collectors, eliminating mechanical fasteners and solder joints that are vulnerable to vibration and shock, while maintaining ease of electrical connection.
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 lithium iron phosphate module provides a heavy-duty, off-road ready automotive design with faster charging, longer range, and improved safety by preventing gas emission, offering a flexible and efficient battery solution with enhanced durability and assembly ease.
Implementation Method 1
at least two current collector plates that are interconnected by a resistive welding process
Data Source
AI summary
Disclosed is a lithium iron phosphate module having seventy-two (72) 26650 lithium iron phosphate cylindrical cells arranged in an 8S9P architecture, with the “S” being the number of supercells connected in series and the “P” being the number of cells connected in parallel. A five-layer clad material forms at least two current collector plates that are interconnected to the lithium iron phosphate cylindrical cells by a resistive welding process. The current collector plates each have a tab custom stamped on the five-layer clad material that is connected to a battery management system by running a voltage sense wire with a quick disconnect tab on the end from the battery management system to the custom stamped tab to monitor and balance the 24V output and 34Ah current of the cells in the module. At least two cell holders enclose the lithium iron phosphate cylindrical cells and the current collector plates.