Separator Coating Adsorbs Transition Metal Ions
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Solution Overview
Problem
Lithium ion batteries face safety issues due to excessive transition metal ion dissolution during overcharging, leading to thermal instability and potential explosions, as conventional separators fail to effectively manage these ions and heat shrinkage at high temperatures.
Innovation Solution
A separator with a porous substrate coated on both sides with a mixture of boehmite and non-boehmite particles, a binder polymer, and an anionic surfactant, which adsorbs transition metal ions like Mn, Ni, and Co, preventing their deposition on the anode and reducing heat-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based porous substrate is used as a separator, then it provides basic separation function, but it shows severe heat shrinking behavior at 100°C or higher causing short-circuit between electrodes
Solution Approach 1:
The patent applies composite materials by combining polyolefin-based porous substrate with inorganic particles (alumina, silica, boehmite) and binder polymers to create a separator coating layer that maintains structural integrity at high temperatures while preventing heat shrinking of the base substrate
Solution Approach 2:
The patent changes the thermal parameters of the separator by incorporating inorganic particles with high heat resistance and adjusting the composition ratio of binder polymer to substrate, enabling the separator to maintain dimensional stability at temperatures of 100°C or higher
2Reliability
If conventional separators are used, then manufacturing is simple, but they fail to adsorb excessive transition metal ions causing thermal instability and potential explosions
Solution Approach 1:
The patent applies local quality by forming a coating layer with specific inorganic particles and binder polymers only on the surface of the porous substrate, concentrating the metal ion adsorption function in this localized region while maintaining the simplicity of the bulk substrate structure
Solution Approach 2:
The patent uses porous materials including porous polymer substrates and inorganic particles with porous structures to provide both mechanical support and enhanced surface area for metal ion adsorption, improving safety without significantly increasing structural complexity
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 solution enhances the cycle life and high-temperature storage capability of batteries by effectively adsorbing transition metal ions and controlling heat absorption, thereby preventing overheating and explosions.
Implementation Method 1
a separator capable of adsorbing an excessive amount of transition metal ions from a cathode
Implementation Method 2
excellent heat-absorbing property of the boehmite particles
Data Source
AI summary
A separator and an electrochemical device including the same. The separator includes: a porous substrate having a plurality of pores; and a first porous coating layer and a second porous coating layer formed on one surface and the other surface of the porous substrate, respectively, and including a plurality of inorganic particles, a binder polymer disposed on a part or the whole of the surface of the inorganic particles so that the inorganic particles are connected and fixed with each other, and an anionic surfactant, wherein the inorganic particles include boehmite particles and non-boehmite particles, and the boehmite particles and the binder polymer are present at a weight ratio of 1:1-1:5.