Electroactive Separator for Overcharge Protection
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Solution Overview
Problem
Existing electrochemical storage batteries face damage and safety risks due to overcharging, with current methods for overcharge protection being costly, complex, or limited in effectiveness, such as external electronic circuits and redox shuttles, which can be unreliable and inefficient.
Innovation Solution
Incorporating an electroactive material into the separator of electrochemical cells that becomes electronically conductive upon overcharge, creating a shunt between electrodes to prevent damage, using a composite or porous solid-state separator with materials like ceramic oxides or electroactive polymers that are insulating within normal voltage ranges but conductive beyond a threshold, allowing for internal overcharge protection without adding mass or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external electronic circuits are used for overcharge protection, then cell safety is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the overcharge protection function from external electronic circuits and relocates it into the separator material itself. The separator incorporates electroactive materials that automatically respond to overcharge conditions through redox reactions, eliminating the need for separate monitoring and control circuits while maintaining safety functionality.
Solution Approach 2:
The separator performs self-protection by incorporating electroactive materials that automatically detect and respond to overcharge conditions. When the cell voltage exceeds the safe operating window, the electroactive material undergoes redox reactions that create an electronic shunt, automatically limiting the voltage without requiring external control systems.
2Reliability
If redox shuttles are used for overcharge protection, then cell safety is improved, but charging rate capability deteriorates
Solution Approach 1:
The patent merges the redox shuttle functionality directly into the separator structure. Instead of using separate shuttle molecules that diffuse through the electrolyte, the electroactive material is integrated into the separator matrix, creating a unified structure that provides both separation and overcharge protection functions simultaneously.
Solution Approach 2:
The separator utilizes a porous structure containing electroactive materials that can rapidly undergo redox reactions. The porous architecture allows for efficient ion transport while the electroactive sites provide fast electron transfer pathways, enabling high charging rates without compromising safety protection.
3Reliability
If redox shuttle additive concentration is increased to improve limiting current density, then overcharge protection capability is improved, but solubility limitations are exceeded
Solution Approach 1:
The patent creates a composite separator material combining porous structural material with electroactive compounds. This composite structure allows high concentrations of electroactive material to be incorporated into the separator matrix without solubility limitations, as the electroactive material is dispersed as solid particles or integrated into the polymer structure rather than dissolved in the electrolyte.
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
This solution provides effective overcharge protection for electrochemical cells, enabling full charging without risk of damage, with the electroactive shunt allowing high charging currents and being stable against reduction, thus preventing irreversible changes and maintaining cell voltage within safe limits.
Implementation Method 1
the oxidized form of the shuttle additive diffuses through the cell to the negative electrode where it is reduced to its original (unoxidized) state
Implementation Method 2
The net effect is an internal shunt which prevents damage to the cell by imposing a limit on cell potential
Implementation Method 3
the electroactive polymer becomes electronically conductive and creates an electronic shunt between the electrodes of the electrochemical cell
Data Source
AI summary
Porous separators for use in electrochemical cells and methods of their manufacture are provided. The separators are porous structures comprising an electroactive material and an electronically insulating structural material, wherein the electroactive material forms a percolating path in the separator.