Ceramic Separator Structure for TMCCC Cell Thermal Stability
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Solution Overview
Problem
Electrochemical cells with transition metal cyanide coordination compound (TMCCC) electrodes face degradation issues due to the release of chemical species into the electrolyte, leading to performance loss and safety risks, and existing separator materials do not adequately address these challenges, particularly in terms of thermal stability and compatibility with TMCCC electrodes.
Innovation Solution
Incorporating a ceramic component into the separator, either as nanoparticles or in a discrete multilayer construction, to enhance thermal stability and compatibility, thereby improving the cycle life and safety of TMCCC-containing electrochemical cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin separator is used in TMCCC electrochemical cells, then the separator provides basic ionic conductivity and electronic insulation, but the separator exhibits poor thermal stability and shrinks or melts upon heat exposure causing short circuits
Solution Approach 1:
The patent applies composite materials by combining polyolefin base material with ceramic species (such as alumina, silica, or boehmite) to create a separator that maintains the ionic conductivity and electronic insulation of polyolefin while adding thermal stability through the ceramic component. The ceramic species prevent shrinkage and melting at elevated temperatures, resolving the thermal stability issue without sacrificing the functional properties of the polyolefin separator.
2Reliability
If surface coatings are applied to TMCCC electrode materials to prevent chemical species release, then degradation is reduced, but charge transfer is limited and charge/discharge rates decrease
Solution Approach 1:
The patent uses the separator with ceramic species as an intermediary barrier between the TMCCC electrode materials and the electrolyte. The ceramic-containing separator prevents release of chemical species (such as transition metal cations) into the electrolyte while maintaining sufficient ionic conductivity to allow charge transfer. This mediator approach protects the electrode stability without limiting the charge/discharge rates, unlike direct surface coatings on the electrodes.
3Productivity
If separator thickness is reduced to improve rate capability, then cell impedance decreases and rate capability improves, but thermal stability and short circuit prevention are compromised
Solution Approach 1:
The patent enables use of thinner separators by incorporating ceramic species into the polyolefin matrix. The ceramic component provides thermal stability and dimensional integrity even at reduced thickness, allowing the separator to maintain short circuit prevention capabilities while being thin enough to enable high rate capability and low cell impedance.
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 use of ceramic components in the separator significantly extends the cycle life of TMCCC-containing electrochemical cells by improving thermal stability and preventing short circuits, while maintaining high ionic conductivity and energy efficiency.
Implementation Method 1
This is attributed to a higher thermal capacity of those ceramic species when compared to polyolefin materials.
Implementation Method 2
Electrochemical cells are designed such that two electrodes are separated by a separator that electronically insulates the two electrodes while also being ionically conductive to allow ions to diffuse between the electrodes
Data Source
AI summary
An electrochemical cell having one or more electrodes with TMCCC materials introduces improved performance by including a special separator having ceramics and/or a discrete multilayer construction. TMCCC materials with no surface modifications, and existing electrolytes with no composition modifications are combined with a different grade of separator to improve cell performance.