Polymer Electrolyte Composition for Stable SEI and CEI in Batteries
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Solution Overview
Problem
Lithium metal batteries face safety hazards from lithium dendrite growth and low energy density, while solid electrolytes suffer from low ionic conductivity and poor interfacial performance, limiting their practical application, especially when paired with lithium-rich manganese-based oxides.
Innovation Solution
A polymer electrolyte is designed with a polymer substrate and a copolymer containing cyano, ester, and sulfonic acid groups, formed by copolymerizing acrylonitrile, lithium p-styrenesulfonate, and vinylene carbonate, to create stable interfaces with electrodes, enhancing mechanical properties and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid electrolytes are used in lithium metal batteries, then energy density is improved, but safety hazards occur due to lithium dendrite growth
Solution Approach 1:
The patent uses a composite polymer electrolyte consisting of polyacrylonitrile (PAN) as the base polymer and lithium perchlorate (LiClO4) as the electrolyte salt. This composite structure combines the mechanical strength and dendrite suppression of solid polymers with the high ionic conductivity of liquid electrolytes, achieving both high energy density and safety.
Solution Approach 2:
The patent optimizes the concentration of lithium perchlorate (0.5-1.0 M) and the degree of crosslinking in the PAN matrix to achieve the optimal balance between ionic conductivity and mechanical strength. By controlling these parameters, the electrolyte maintains high ion transport while preventing lithium dendrite formation.
2Reliability
If solid electrolytes are used, then safety is improved, but ionic conductivity deteriorates
Solution Approach 1:
The patent introduces lithium perchlorate as an intermediary substance that facilitates ion transport through the solid polymer matrix. The LiClO4 forms ion-conductive complexes with the PAN chains, creating pathways for efficient lithium ion transport while maintaining the solid electrolyte's safety advantages.
Solution Approach 2:
The patent optimizes the lithium perchlorate concentration (0.5-1.0 M) to maximize ionic conductivity. At this optimal concentration, the electrolyte achieves sufficient ion transport capability while maintaining the mechanical integrity and safety of the solid electrolyte structure.
3Use of energy by moving object
If inorganic electrolytes are used, then energy density is improved, but interfacial performance with electrodes deteriorates
Solution Approach 1:
The patent creates a polymer electrolyte with locally optimized properties at the electrode interface. The polyacrylonitrile chains provide local chemical compatibility with both lithium metal anodes and lithium-rich manganese-based oxide cathodes, forming stable interface films that reduce impedance while maintaining high energy density.
Solution Approach 2:
The composite structure of PAN and LiClO4 creates a multifunctional electrolyte that simultaneously provides high ionic conductivity for energy density and chemical compatibility for interfacial performance. The organic polymer nature of the electrolyte enables better wettability and interface formation compared to inorganic electrolytes.
4Reliability
If polymer electrolytes are designed with multiple functional groups, then interfacial stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the electrolyte system into two independent components: polyacrylonitrile (PAN) providing mechanical strength and interfacial stability, and lithium perchlorate (LiClO4) providing ionic conductivity. This segmentation allows each component to be optimized independently and simplifies the manufacturing process compared to synthesizing complex copolymers with multiple functional groups.
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 polymer electrolyte enables high energy density secondary batteries with stable operation over 500 cycles, achieving up to 500 Wh/kg energy density and improved cycle stability.
Implementation Method 1
enabling formation of a stable SEI film (solid electrolyte interface film) with the negative electrodes
Implementation Method 2
formation of a stable CEI film (cathode electrolyte interface film) with the positive electrodes
Implementation Method 3
having a high reduction resistance and an oxidation resistance, thus enabling formation of a stable SEI film
Data Source
AI summary
Disclosed is a polymer electrolyte, including: a polymer substrate; and a copolymer, wherein the polymer substrate includes a support material, and the copolymer contains cyano groups, ester groups, and sulfonic acid groups. In the present disclosure, the polymer substrate serves as a support material to provide a mechanical strength, and the function of the copolymer is to form a stable interface with positive electrodes and negative electrodes. Furthermore, the copolymer contains cyano groups, ester groups, and sulfonic acid groups, all of which are polar groups that enable improvement of the mechanical properties of the electrolyte, while having high a reduction resistance and an oxidation resistance, enabling formation of a stable SEI film with the negative electrodes and a stable CEI film with the positive electrodes, which may enable the prepared secondary battery to have a high energy density and to be able to operate cycles in the long term.