Composite Separator Pore Obstruction High-Voltage Battery
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Solution Overview
Problem
High-voltage cathode active materials in secondary batteries can obstruct the pores of separators, leading to rapid degradation in cycle capacity at high temperatures, and existing separators made from polyolefin-based resins are prone to shrinkage and short circuits due to their low melting point.
Innovation Solution
A composite separator with a porous coating layer formed on a porous substrate, using inorganic particles and an organic binder polymer, which allows for improved lithium-ion conductivity and prevents pore obstruction, is used in conjunction with high-voltage cathode active materials, ensuring the separator's pores remain open and preventing dendrite formation on the anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyethylene-based separator is used together with a high-voltage cathode active material, then the separator can prevent short circuits between cathode and anode, but metallic ions released from the cathode active material form dendrites on the anode and obstruct the pores of the separator, causing rapid decrease in cycle capacity at high temperature
Solution Approach 1:
The patent applies composite materials by combining a polyethylene-based separator with a porous coating layer containing inorganic particles (such as alumina, silica, or titania) and binder polymer. This composite structure allows the separator to maintain its short circuit prevention function while the porous coating layer prevents pore obstruction by dendrites, thereby preserving cycle capacity at high temperatures.
Solution Approach 2:
The patent utilizes porous materials by forming a porous coating layer on the separator surface with controlled porosity (30-70%). This porous structure allows lithium ion transport while preventing dendrite formation and pore obstruction, resolving the contradiction between short circuit prevention and cycle capacity retention.
2Productivity
If a thinner separator is used to increase discharge capacity, then the concentration of liquid electrolyte around the separator increases and substance movement is facilitated, but the separator becomes more susceptible to shrinkage and melting at high temperature when made from polyolefin-based resins
Solution Approach 1:
The patent applies composite materials by combining a thin polyethylene-based separator with a porous coating layer containing inorganic particles. This composite structure enables the use of thinner separators for higher discharge capacity while the inorganic particles in the coating layer provide thermal stability and prevent shrinkage or melting at high temperatures.
Solution Approach 2:
The patent changes physical parameters by controlling the pore size (10 nm to 5 μm), porosity (30-70%), and thickness of the porous coating layer. These parameter optimizations allow the thin separator to maintain both high discharge capacity through improved ion transport and thermal stability through the heat-resistant inorganic coating.
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 effectively inhibits rapid cycle capacity decline at high temperatures and enhances the overall life performance of high-voltage secondary batteries by maintaining the integrity of the separator's pores and preventing short circuits, thereby improving safety and performance.
Implementation Method 1
the separator comprises a porous substrate and a porous coating layer formed on at least one surface of the porous substrate and comprising inorganic particles and an organic binder polymer, and has pores whose longest diameter ranges from 10 nm to 5 μm
Data Source
AI summary
The present disclosure refers to a secondary battery which comprises a high-voltage cathode active material and a separator whose pores are not obstructed even though being used together with the high-voltage cathode active material, thereby preventing the obstruction of pores in the separator and the formation of a dendrite in the anode and eventually providing good battery life performance.