Battery Pack Endothermic Agent Short-Circuit Heat Management
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Solution Overview
Problem
Battery packs with lithium-ion secondary cells connected in series face temperature elevation issues due to short-circuit currents generated by conductive foreign matter penetration, leading to potential denaturation of internal materials and instability.
Innovation Solution
A battery pack design with layered electrode bodies and strategically placed endothermic agents between negative and positive electrode sheets and the battery case, which absorb Joule heat generated by short-circuit currents, preventing temperature elevation across connected cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If endothermic agents are added to envelope film or enveloping pack material, then temperature increase can be inhibited, but temperature elevation caused by short-circuit current through conductive foreign matter cannot be effectively prevented
Solution Approach 1:
The patent introduces a current interrupting member as an intermediary component positioned between electrode sheets. This member acts as a mediator that interrupts short-circuit current paths when conductive foreign matter penetrates the battery pack, preventing Joule heat generation at the penetration site. The current interrupting member is specifically designed to be non-conductive or have low conductivity, thereby breaking the electrical continuity that would otherwise allow harmful currents to flow through the conductive foreign matter.
Solution Approach 2:
The patent implements preliminary protective measures by pre-positioning current interrupting members and insulating structures within the battery pack design before any foreign matter penetration occurs. The current interrupting members are strategically placed between electrode sheets in advance, and insulating films are pre-applied to conductive foreign matter barriers, creating a preemptive defense system that activates immediately upon penetration without requiring real-time response.
2Object-generated harmful factors
If conductive foreign matter penetrates single cells, then short-circuit current flows and Joule heat is generated, but existing endothermic agents cannot prevent this temperature elevation
Solution Approach 1:
The patent extracts the harmful short-circuit current path from the system by introducing current interrupting members that physically break the electrical continuity. By removing the conductive path that allows current to flow through foreign matter, the source of Joule heat generation is eliminated. The endothermic agents are retained but their role is supplemented by this extraction of the harmful current path.
Solution Approach 2:
The patent converts the potentially harmful situation of foreign matter penetration into a beneficial outcome by using the penetration event itself to trigger protective mechanisms. When conductive foreign matter penetrates, it contacts the current interrupting member or insulating film, which then interrupts the current flow. The endothermic agents simultaneously absorb any heat that does generate, transforming the harmful thermal effect into a controlled, manageable process that ultimately protects the battery.
3Reliability
If short-circuit current flows through bus bars between single cells, then temperature elevation occurs in downstream cells, but conventional designs lack protection against this inter-cell current flow
Solution Approach 1:
The patent segments the electrical pathways between single cells by introducing current interrupting members and insulating structures at strategic locations. These segments create isolated electrical zones that prevent short-circuit currents from propagating across multiple cells through bus bars. Each cell's electrical integrity is protected independently, containing any potential short-circuit events within individual cells rather than allowing inter-cell current flow.
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
Effectively inhibits temperature elevation and maintains stability by early absorption of Joule heat, preventing denaturation and ensuring safety and performance of the battery pack.
Implementation Method 1
Joule heating (resistive heating) of the short-circuit current E1 flowing through the conductive foreign matter F raises the internal temperatures of the single cells 110A, 110B
Implementation Method 2
an endothermic agent composed of a compound capable of conducting an endothermic reaction is added to an envelope film or an enveloping pack material of the secondary cell and the battery pack, in order to inhibit a temperature increase that can occur upon abnormal heat production of the cells
Data Source
AI summary
Provided is a battery pack having a plurality of single cells connected to one another, the battery pack being capable of preventing a temperature elevation caused by a short-circuit current that is generated when a sharp conductive foreign matter penetrates each of the single cells. In the battery pack disclosed herein, the single cells are arranged alternately adjacent to one another, and these adjacent single cells are electrically connected in series, and layered electrode bodies of these single cells have the following configurations. Among positive electrode sheets and negative electrode sheets, a negative electrode sheet is disposed on the uppermost stream side, and an endothermic agent is disposed as a layer between this negative electrode sheet and a positive electrode sheet. A negative electrode sheet is disposed on the lowermost stream side, and an endothermic agent is disposed as a layer between this negative electrode sheet and an inner surface of a battery case.