Plastic-Deforming Battery Separator for Nail Puncture Isolation
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Solution Overview
Problem
Current electrochemical devices, such as lithium-ion batteries, face safety issues due to the risk of internal short circuits and fires when punctured by external objects, as traditional separators fail to effectively prevent large-area short circuits.
Innovation Solution
A separator with a high plastic deformation rate is developed, comprising a porous substrate and a porous layer with inorganic particles and a binder, which extends around a puncturing object to prevent internal short circuits, thereby enhancing safety by maintaining isolation between the cathode and anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional separator is used, then the device structure is simple, but the separator cannot effectively prevent large-area short circuits when punctured
Solution Approach 1:
The separator is constructed as a composite material system consisting of a porous substrate layer and a porous coating layer. The porous substrate provides mechanical strength and baseline separation function, while the porous coating layer containing inorganic particles and binder provides enhanced safety through controlled deformation and wrapping around puncturing objects. This composite structure resolves the contradiction by combining materials with different properties to achieve both reliability and controlled complexity.
Solution Approach 2:
The separator employs local quality differentiation where the porous coating layer is applied specifically on the surface of the porous substrate rather than throughout the entire structure. The coating layer contains inorganic particles and binder in specific ratios (inorganic particles 80-95 wt%, binder 10-20 wt%) to create localized regions with high plastic deformation capability. This allows the separator to maintain simple overall structure while having enhanced safety properties at critical locations where puncture resistance is needed.
2Reliability
If the separator has high plastic deformation rate to wrap around puncturing objects, then safety improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the porous substrate's plastic deformation rate (absolute deformation rate of 40-1800% or relative deformation rate of 50-100%). By controlling these parameters within defined ranges rather than requiring exact values, the invention achieves high safety performance while accommodating normal manufacturing variations. The porous coating layer composition (inorganic particles 80-95 wt%, binder 10-20 wt%) also uses parameter ranges to ensure consistent performance without excessive manufacturing precision requirements.
3Reliability
If the porous layer with inorganic particles and binder is added, then the separator's wrapping effect improves, but the device weight increases
Solution Approach 1:
The separator uses porous materials for both the substrate and the coating layer. The porous structure provides high surface area and volume for the inorganic particles and binder to create wrapping effect, while the porosity reduces the overall material density and weight. The porous coating layer contains voids that reduce mass while maintaining the structural integrity and wrapping capability around puncturing objects, thus resolving the contradiction between wrapping effect and weight.
Solution Approach 2:
The porous coating layer acts as a functional copy or enhancement of the porous substrate's safety function. Rather than making the entire separator thick and heavy, a thin coating layer (3-20 μm) is applied on the substrate surface to provide the wrapping effect. This coating copies the essential safety function in a simplified, lightweight form, avoiding the need for substantial weight increase while achieving the desired wrapping capability.
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 high plastic deformation rate of the separator significantly reduces the probability of internal short circuits and fires in lithium-ion batteries during nail penetration tests, improving the overall safety performance.
Implementation Method 1
the porous substrate has an absolute plastic deformation rate in a first direction ranging from about 40% to about 1800%
Data Source
Figure 1~2
AI summary
The present application relates to a separator and an electrochemical device. The present application provides a separator comprising: a porous substrate and a porous layer, wherein the porous layer is disposed on a surface of the porous substrate and comprises inorganic particles and a binder. The porous substrate has an absolute plastic deformation rate in a first direction ranging from about 40% to about 1800%. By using the separator provided in the present application, the safety performance of lithium ion batteries is improved.