Built-In BMS Layout for Cylindrical Lithium Batteries
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Solution Overview
Problem
Cylindrical lithium batteries with external BMS systems face issues of reduced battery capacity, increased weight, higher manufacturing costs, and complex installation due to the separation of the BMS from the battery cell, limiting their application and performance.
Innovation Solution
A production process for a rechargeable cylindrical lithium battery with a built-in BMS board, integrating the BMS board within the battery cell, involving cap making, battery cell manufacturing, and finished product assembly processes, including steps such as mounting electronic components, spraying waterproof coatings, laser-welding, and electrolyte injection, to ensure electrical connection and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the BMS is separated from the battery cell and placed in an independent sealed battery cell, then the battery can have a BMS system, but the battery cell size is greatly reduced, battery capacity is reduced, and the overall weight increases
Solution Approach 1:
The patent merges the BMS circuit board directly into the battery cell structure, eliminating the need for a separate sealed battery cell. The BMS board is integrated within the battery housing, allowing the battery to maintain full capacity while incorporating BMS functionality. This combining approach resolves the contradiction by achieving both BMS reliability and maximum battery capacity without the weight penalty of separate components.
2Reliability
If the BMS is separated from the battery cell, then the battery can have a BMS system, but the manufacturing cost increases and installation during production becomes complex
Solution Approach 1:
The BMS board is integrated directly into the battery cell assembly process, combining previously separate manufacturing steps into a unified workflow. The circuit board is positioned and connected within the battery housing during the same manufacturing cycle, eliminating the need for separate assembly operations. This merging of functions simplifies production, reduces manufacturing costs, and maintains BMS reliability.
3Quantity of substance
If the BMS board is built-in within the battery cell, then the battery capacity is maximized, but the BMS board needs to be protected from electrolyte and electrical connection must be ensured
Solution Approach 1:
The patent uses a waterproof coating as an intermediary barrier between the BMS board and the electrolyte. This protective layer allows the BMS board to be positioned close to the battery cell for maximum capacity utilization while preventing electrolyte contact. The waterproof coating serves as the mediator that enables both close integration for capacity and protection for reliability.
Solution Approach 2:
The patent replaces traditional mechanical sealing methods with a waterproof coating applied to the BMS board. This coating-based approach provides more reliable protection against electrolyte while allowing flexible positioning of the BMS board within the battery cell for optimal capacity utilization. The coating substitution enables both protection and electrical connection without complex mechanical sealing structures.
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 integrated BMS board minimizes size and weight impacts, enhances battery stability and safety, and provides effective charging and discharging management, while maintaining low production costs and simplicity.
Implementation Method 1
laser-weld a positive electrode of the battery cell to the edge of the back of the positive aluminum cap; laser-weld a negative aluminum foil to the inner bottom of the steel shell
Implementation Method 2
Spray waterproof coating on a plastic support
Implementation Method 3
spray glue, air-dry... Put a positive aluminum cap into the plastic support with glue air-dried
Implementation Method 4
inject electrolyte... make the entire circle of the opening of the steel shell rolled inwards to be extruded on the negative metal ring, conducting the negative electrode
Data Source
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AI summary
The invention discloses a production process for a rechargeable cylindrical lithium battery with a built-in BMS board, which includes a cap production process, a battery cell production process and a finished product assembly and production process, solves the size and weight problems caused by the traditional external BMS by integrating the BMS board inside the cylindrical lithium battery, and has high integration level and stability, providing protection for battery charging and discharging, and improving the safety performance of the battery.