Insulated Positive Current Collector for Internal Short Circuit Resistance
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Solution Overview
Problem
Lithium ion batteries face safety hazards due to internal short circuits caused by abnormal conditions like collision, extrusion, or puncture, leading to potential fires or explosions, and existing solutions fail to effectively prevent these incidents while maintaining normal battery operation.
Innovation Solution
The battery design incorporates a positive current collector with an insulation layer and a conductive layer of specific thickness, along with a protective layer, to enhance short circuit resistance and safety performance, while using a copper foil current collector for the negative electrode to ensure rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alloy having low melting point is added into the material of metal current collector, then safety is improved by breaking circuit when temperature rises, but the battery cannot continue to operate and normal operation is affected
Solution Approach 1:
The current collector is divided into multiple functional layers: a base metal layer (Al or Cu) providing structural support and conductivity, and a separate safety layer (low-melting-point alloy or resin-coated metal) providing thermal protection. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between safety and normal operation.
Solution Approach 2:
The invention changes the melting point parameter of the current collector by incorporating low-melting-point materials (alloys melting at 100-500°C or resin coatings) into the structure. This parameter modification enables the current collector to respond to thermal runaway at controlled temperatures, achieving safety without compromising normal battery operation at operating temperatures.
2Reliability
If multilayered current collector with resin layer is adopted, then safety is improved by melting resin layer to cut off current, but the battery cannot continue to operate under abnormal conditions
Solution Approach 1:
The invention introduces an intermediary safety layer (resin coating or low-melting-point alloy layer) between the base metal current collector and the electrode. This intermediary layer acts as a thermal barrier and circuit breaker during thermal runaway, while being transparent to normal battery operation, thus resolving the contradiction between safety and continuous operation capability.
3Quantity of substance
If thickness of conductive layer is reduced to increase weight energy density, then weight energy density is improved, but conductivity and rate performance may be affected
Solution Approach 1:
The invention uses composite material structures for the current collector, combining highly conductive metals (Al, Cu) with functional safety layers. The base metal layer maintains excellent conductivity even at reduced thickness, while the safety layer provides thermal protection. This composite approach allows thinning of the current collector to improve weight energy density without sacrificing rate performance.
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
This design significantly reduces the risk of heat generation and damage from internal short circuits, improving safety performance while maintaining good rate performance and increasing weight energy density.
Implementation Method 1
The positive current collector includes an insulation layer and at least one conductive layer. The insulation layer is used to support the at least one conductive layer.
Implementation Method 2
Each of the at least one conductive layer is used to support the positive active material layer and is located above at least one surface of the insulation layer.
Implementation Method 3
The negative current collector is a copper foil current collector having a thickness of 1 μm to 5.9 μm.
Data Source
AI summary
A battery is provided in the present disclosure. The battery includes: a positive electrode plate including a positive current collector and a positive active material layer; a negative electrode plate including a positive current collector and a negative active material layer; and an electrolyte. The positive current collector includes an insulation layer used to support a conductive layer and the conductive layer used to support the positive active material layer and located above at least one surface of the insulation layer. The conductive layer has a thickness of D2 which satisfies: 300 nm≤D2≤2 μm. A protective layer is arranged on at least one surface of the conductive layer. The negative current collector is a copper foil current collector having a thickness of 1 μm to 5.9 μm.