Ion-Capturing Separator Coating for High-Voltage Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium batteries experience increased resistance and reduced lifespan due to the formation of an unstable solid-electrolyte interphase (SEI) film and side reactions caused by the elution of transition metal ions, post-transition metal ions, and metalloid ions during high voltage charging or high temperature storage.
Innovation Solution
A separator for lithium batteries with a coating layer containing a compound represented by Chemical Formula 1 that captures transition metal ions, post-transition metal ions, and/or metalloid ions, reducing their elution into the electrolyte and minimizing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high voltage charging or high temperature storage is performed, then battery capacity and energy density are improved, but transition metal ions elute from the positive electrode into the electrolyte causing increased resistance and reduced lifespan
Solution Approach 1:
A coating layer comprising a compound of Chemical Formula 1 is formed on the positive electrode to act as an intermediary barrier. This coating layer captures transition metal ions (such as Mn, Co, Ni) that elute from the positive electrode active material, preventing them from entering the electrolyte and reaching the negative electrode. The coating layer thus mediates between the positive electrode and electrolyte, allowing high voltage charging while blocking harmful ion transport that would otherwise reduce battery lifespan.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrode surface by introducing a coating layer with specific chemical groups (such as carboxyl, hydroxyl, or amine groups) that have high affinity for transition metal ions. This parameter change in the surface chemistry enables selective capture of eluted ions, allowing the battery to operate at high voltages without the detrimental effects of ion elution, thereby resolving the contradiction between capacity and lifespan.
2Reliability
If transition metal ions are captured by the separator, then resistance increase rate is improved, but the separator structure becomes more complex
Solution Approach 1:
The separator is divided into functional segments: a base separator layer providing mechanical separation and safety shutdown function, and a coating layer comprising a compound of Chemical Formula 1 providing ion capture function. This segmentation allows each layer to specialize in its primary function while working together, improving resistance increase rate without requiring complete redesign of the entire separator structure.
Solution Approach 2:
The separator is constructed as a composite material system combining the base separator material (such as polyolefin) with the ion-capturing compound of Chemical Formula 1. This composite structure integrates the mechanical properties of the base separator with the chemical functionality of the coating layer, achieving effective ion capture while maintaining the structural integrity and simplicity of the overall separator design.
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 separator effectively captures these ions, reducing resistance increase and improving the battery's lifespan and high-temperature storage characteristics by preventing ion precipitation on the negative electrode surface.
Implementation Method 1
the coating layer includes a compound represented by Chemical Formula 1 below... the separator may capture the transition metal ions, post-transition metal ions, and/or metalloid ions eluted into the electrolyte
Data Source
AI summary
The present disclosure relates to a separator for a rechargeable lithium battery, and a rechargeable lithium battery including the separator. The separator for a rechargeable lithium battery includes a porous substrate, and a coating layer located on at least one surface of the porous substrate.