Crosslinked Polycarbonate Electrolyte for Strength-Conductivity Balance
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Solution Overview
Problem
Solid polymeric electrolytes based on polyethers, such as POE, have limited ion transport number and ionic conductivity due to their stable coordination structure, crystallinity, and low electrochemical stability, while alternative polymers like PTMC offer improved stability and conductivity but suffer from mechanical weakness, particularly at high temperatures.
Innovation Solution
A quasi-solid electrolyte is developed by crosslinking dihydroxylated polyalkylene carbonate with a triisocyanate compound in the presence of a plasticizing agent, creating a crosslinked polymer network that traps the plasticizer, enhancing mechanical strength and ionic conductivity while maintaining flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If poly(trimethylene carbonate) (PTMC) is used as an alternative polymer to polyethers, then electrochemical stability and ionic conductivity are improved, but mechanical strength deteriorates
Solution Approach 1:
The patent combines PTMC polymer with inorganic fillers (such as TiO2, SiO2, Al2O3, or their composites) to create a composite solid polymer electrolyte. The inorganic filler forms a three-dimensional skeleton structure that reinforces the polymer matrix, significantly improving mechanical strength while preserving the electrochemical stability and ionic conductivity of PTMC. This composite approach allows the electrolyte to maintain both softness for ion transport and structural integrity.
2Adaptability or versatility
If polyethers are used as solid polymeric electrolytes, then flexibility is improved, but ionic conductivity deteriorates
Solution Approach 1:
The patent introduces inorganic filler particles distributed throughout the polymer matrix, creating regions with different properties. The polymer-rich regions maintain flexibility and chain mobility for ion transport, while the filler-rich regions provide structural support and additional ionic conduction pathways. This local differentiation allows simultaneous achievement of flexibility and high ionic conductivity.
Solution Approach 2:
The inorganic filler creates a porous or networked structure within the polymer electrolyte. This porous structure provides additional pathways for ion transport while maintaining the flexibility of the polymer matrix. The interconnected pores allow efficient ion conduction without compromising the mechanical flexibility needed for battery assembly and operation.
3Strength
If inorganic filler is added to enhance mechanical strength, then strength is improved, but device complexity increases
Solution Approach 1:
The inorganic filler serves multiple functions simultaneously: it acts as a mechanical reinforcement to improve strength, provides additional ionic conduction pathways to enhance conductivity, and stabilizes the polymer matrix to improve electrochemical stability. This multi-functionality reduces the need for additional components or complex formulations, simplifying the overall device design while achieving multiple performance goals.
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 quasi-solid electrolyte achieves a balance between mechanical strength and ionic conductivity, with conductivities greater than non-crosslinked PTMC at various temperatures, and exhibits stability suitable for energy storage devices over a wide temperature range.
Implementation Method 1
crosslinking of at least one polyalkylene carbonate by a triisocyanate compound
Implementation Method 2
in the presence of at least one plasticizing agent... creating a crosslinked polymer network that traps the plasticizer, enhancing mechanical strength and ionic conductivity while maintaining flexibility
Implementation Method 3
The transport of the proton or the alkali or alkaline-earth cation, in particular the lithium cation, between the positive electrode and the negative electrode, is ensured by an ionic conductive electrolyte
Data Source
Figure 1a~1c
Figure 2~3
Figure 4
AI summary
The invention relates to a process for preparing a quasi-solid electrolyte comprising at least the following steps: (i) having a composition comprising at least one plasticizing agent; at least one polyalkylene carbonate having two free terminal hydroxyl groups and having an average molar mass Mw less than or equal to 200,000 g.mol-1; at least one triisocyanate compound in a dihydroxylated polycarbonate(s)/triisocyanate(s) mass ratio of between 0.5 and 5; at least one alkali or alkaline earth metal salt; at least one catalyst for the coupling reaction between a hydroxyl group and an isocyanate group; and optionally at least one inorganic filler; and (ii) crosslinking said composition to form said quasi-solid electrolyte. It further relates to the quasi-solid electrolyte thus obtained and its use in an electrochemical system, in particular in a lithium battery.