Composite Positive Electrode Collector for Nail-Piercing Safety
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Solution Overview
Problem
Lithium-ion batteries face safety concerns, particularly with nail piercing, which can lead to internal short circuits and thermal runaway due to the lack of effective means to prevent metal burrs from causing direct contact between the positive and negative electrodes.
Innovation Solution
A positive electrode piece with a composite current collector featuring a thin conductive aluminum or aluminum alloy layer and a polymer-based support layer, along with a primer layer containing conductive material and binder, enhances electrical conductivity and increases short-circuit resistance, thereby improving nail piercing safety and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional metal current collector is used, then electrical conductivity is good, but nail piercing safety is poor due to metal burrs causing short circuits
Solution Approach 1:
The harmful metal component is extracted from the current collector structure. The patent removes the traditional metal current collector and replaces it with a polymer-based current collector, eliminating the source of metal burrs that cause short circuits during nail piercing, while maintaining electrical conductivity through conductive fillers and coatings.
Solution Approach 2:
The patent changes the material parameters of the current collector from metal to polymer composite. By adjusting the conductivity, tensile strength, and composition parameters of the polymer current collector, it achieves both safety (no metal burrs) and functionality (electrical conductivity), resolving the contradiction between safety and harmful factors.
2Reliability
If a polymer-based current collector is used, then nail piercing safety is improved, but electrical conductivity may be insufficient
Solution Approach 1:
The patent employs composite materials by combining polymer base materials with conductive fillers (such as carbon black, acetylene black, or metal powders) and conductive coatings. This composite structure provides both the safety advantages of polymers (no metal burrs) and the electrical conductivity needed for battery operation.
Solution Approach 2:
Conductive coatings and fillers act as intermediaries to transfer electrical current through the polymer current collector. These intermediary conductive elements bridge the gap between the insulating polymer matrix and the requirement for electrical conductivity, enabling the polymer current collector to function effectively.
3Use of energy by moving object
If the conductive layer thickness is reduced to improve energy density, then weight energy density increases, but electrical conductivity and flow capacity may deteriorate
Solution Approach 1:
The patent uses composite polymer materials with conductive fillers and multi-layer conductive coatings to achieve high electrical conductivity in a thin current collector structure. This allows reduction of current collector thickness and weight while maintaining sufficient conductivity for battery operation.
Solution Approach 2:
The patent optimizes the conductivity parameter of the polymer current collector by adjusting filler content, particle size distribution, and coating composition. By changing these parameters, the current collector achieves high conductivity despite reduced thickness, enabling improved energy density without sacrificing electrical performance.
Data Source
AI summary
The present application relates to the field of battery, in particular to a positive electrode piece, an electrochemical device and an apparatus. The positive electrode piece of the present application includes a current collector and an electrode active material layer arranged on at least one surface of the current collector, where the current collector includes a support layer and a conductive layer arranged on at least one surface of the support layer. The thickness D2 of one side of the conductive layer D2 satisfies 30 nm≤D2≤3 μm, the material of the conductive layer is aluminum or aluminum alloy, and the density of the conductive layer is 2.5 g/cm3 to 2.8 g/cm3, and a primer layer containing a conductive material and a binder is also arranged between the current collector and the electrode active material layer.