Battery Case Charging Structure to Prevent LiAl Alloy Formation
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Solution Overview
Problem
Secondary batteries face issues such as alloy formation on the inner case surface due to electrolyte corrosion, deformation or damage of the positive electrode charging member, and ingress or egress of foreign substances, which affect durability and safety.
Innovation Solution
A secondary battery design incorporating a conductive member and insulating member between the cap plate and terminal, with a conductive member made of polymers and carbon-based fillers, and an insulating member made of high-temperature resistant polymers, along with a structured cap plate and terminal configuration to prevent alloy formation, limit short-circuit currents, and enhance durability and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional positive electrode charging member is used, then the battery structure is simple, but alloy formation occurs on the inner case surface due to electrolyte corrosion
Solution Approach 1:
The patent introduces a positive electrode charging member as an intermediary component between the electrolyte and the inner case surface. This charging member has high resistance to electrolyte corrosion and prevents direct contact between the electrolyte and the case, thereby preventing alloy formation while maintaining structural simplicity.
2Ease of manufacture
If the positive electrode charging member is formed by conventional methods, then the manufacturing process is simple, but the charging member is deformed or damaged by external welding heat source
Solution Approach 1:
The patent employs a double injection molding method where the positive electrode charging member is pre-formed with optimized structural features before final assembly. This preliminary formation ensures the charging member has sufficient mechanical strength and thermal stability to withstand external welding heat sources during subsequent manufacturing steps, preventing deformation or damage.
3Ease of manufacture
If the positive electrode charging member has a smooth surface, then the manufacturing process is simple, but foreign substances can flow into and out of the case
Solution Approach 1:
The patent introduces protrusions and recesses on the surface of the positive electrode charging member, creating localized structural variations. These local features act as physical barriers that prevent foreign substances from flowing into or out of the case, while the overall manufacturing process remains relatively simple through injection molding techniques.
4Power
If the positive electrode charging member has high conductivity, then electrical performance is improved, but short-circuit current increases when negative terminal is shorted to positive case
Solution Approach 1:
The patent optimizes the electrical resistance parameter of the positive electrode charging member to a specific range that balances electrical performance and safety. By controlling the resistance within an appropriate range, the charging member maintains sufficient electrical conductivity for normal operation while limiting short-circuit current when the negative terminal is shorted to the positive case, preventing dangerous current spikes.
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
Prevents alloy formation on the case surface, limits short-circuit currents, and improves durability by preventing foreign substance ingress and egress, enhancing the battery's structural integrity and safety.
Implementation Method 1
The electrical resistance of the conductive member may be 1 kΩ to 1000 MΩ
Data Source
AI summary
An embodiment of the present invention provides a secondary battery wherein, by positively charging a case by a high-resistance positive electrode charging member, an alloy (for example, a lithium aluminum (LiAl) alloy) is not formed on the inner surface of the case by an electrolyte (that is, the case is not corroded), and when a negative electrode terminal is short-circuited to a positive electrode case; a short-circuit current is limited. As an example, the secondary battery according to an embodiment of the present invention comprises: an electrode assembly; a case in which the electrode assembly is accommodated; a cap plate which is coupled to the case and seals the electrode assembly; a terminal which is connected to the electrode assembly and exposed through the cap plate; and a charging member which is interposed between the cap plate and the terminal, wherein the charging member may comprise a conductive member interposed between the cap plate and the terminal, and an insulating member interposed between the conductive member, the cap plate, and the terminal.