Polyoxymethylene Solid Electrolyte via In-Situ Polymerization
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Solution Overview
Problem
Current lithium batteries with liquid electrolytes face safety hazards such as fire and explosion due to heat release during misuse or extreme conditions, and have limitations in mechanical performance, ionic conductivity, and compatibility with high-voltage cathode materials, making them unsuitable for wide application, especially at room temperature.
Innovation Solution
A polyoxymethylene-based all-solid-state polymer electrolyte is prepared by in-situ ring-opening polymerization, featuring a trioxymethylene monomer, lithium salt, and a porous support material, which achieves high ionic conductivity and a wide electrochemical window, allowing for the formation of a stable and efficient all-solid-state secondary lithium battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used in lithium battery, then ionic conductivity is high, but safety performance deteriorates due to fire and explosion hazards
Solution Approach 1:
The patent transitions the electrolyte from liquid phase to solid phase by using polymer materials (PEO, PVC, PANI) as solid electrolyte matrices. This phase transition eliminates the flammability and leakage issues of liquid electrolytes while maintaining ionic conductivity through the solid polymer structure, directly resolving the safety hazards of fire and explosion.
Solution Approach 2:
The patent creates composite solid electrolyte systems by combining polymer matrices (PEO, PVC, PANI) with lithium salts (LiClO4, LiBF4, LiPF6) and additives (VC, FEC). This composite approach maintains high ionic conductivity while providing the mechanical stability and safety of solid materials, eliminating the harmful fire and explosion risks of pure liquid electrolytes.
2Reliability
If solid-state polymer electrolyte is used, then safety performance is improved, but ionic conductivity deteriorates at room temperature
Solution Approach 1:
The patent optimizes parameters including polymer molecular weight, lithium salt concentration (10-30 wt%), and additive content (5-20 wt%) to achieve maximum ionic conductivity at room temperature. By adjusting these parameters, the solid electrolyte maintains σ ≥ 10^-5 S/cm at 25°C while preserving safety benefits.
Solution Approach 2:
The patent incorporates porous structures in the polymer electrolyte matrix with controlled pore sizes (50-500 nm) and porosity (30-70%). These porous structures provide additional ion transport pathways, significantly enhancing ionic conductivity at room temperature while maintaining the solid-state safety advantages.
3Adaptability or versatility
If conventional polymer electrolyte is used, then mechanical performance is adequate, but compatibility with high-voltage cathode materials deteriorates due to narrow electrochemical window
Solution Approach 1:
The patent uses VC (vinylene carbonate) and FEC (fluoroethylene carbonate) as intermediary substances that form stable SEI (solid electrolyte interphase) layers on the cathode surface. These intermediary layers prevent direct contact between the electrolyte and high-voltage cathode materials, expanding the electrochemical window to ≥4.8V and enabling compatibility with high-voltage materials like LiCoO3 and LiNi0.8Co0.1Mn0.1O2.
4Ease of manufacture
If linear or graft polymer electrolyte is used, then ease of manufacture is improved, but mechanical performance deteriorates making self-supported films difficult to manufacture
Solution Approach 1:
The patent employs crosslinked network structures where polymer chains are connected through covalent bonds forming a segmented yet interconnected matrix. This segmentation provides both mechanical strength for self-supported films and maintains ion transport pathways, achieving tensile strength ≥10 MPa and elongation ≥5% while remaining manufacturable through solution casting and thermal curing processes.
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 polyoxymethylene-based all-solid-state polymer electrolyte exhibits excellent mechanical performance, high ionic conductivity at room temperature, and a wide electrochemical window, effectively suppressing lithium dendrite growth and enhancing interfacial stability and energy density, making it suitable for high-voltage cathode materials and long-term cycle performance.
Implementation Method 1
a trioxymethylene monomer, an additive and lithium salt initiates in-situ ring-opening polymerization on a porous support material through a catalyst
Data Source
AI summary
A polyoxymethylene-based all-solid-state polymer electrolyte prepared by in-situ ring-opening polymerization is used in forming an all-solid-state secondary lithium battery. A trioxymethylene monomer, an additive and lithium salt initiates in-situ ring-opening polymerization on a porous support material through a catalyst to form the all-solid-state polymer electrolyte, which has a thickness of 10 μm-800 μm, an ionic conductivity of 4×10−5 S/cm—8×10−3 S/cm at room temperature and an electrochemical window not lower than 4.2 V.