Cellulose-Based Solid Polymer Electrolyte for Lithium Batteries
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Solution Overview
Problem
Current solid polymer electrolytes for lithium and sodium batteries face limitations such as concentration polarization, lower power capability, and safety issues due to lithium dendrite growth, which are not adequately addressed by existing materials like PEO-based systems, particularly concerning mechanical integrity and ionic conductivity.
Innovation Solution
The development of cellulose derivatives covalently grafted with organic sodium or lithium salts to create self-standing single-ion conducting polymer electrolyte membranes, which are used in all-solid-state batteries, enhancing mechanical properties and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEO-based solid polymer electrolytes are used to ensure safety and non-volatility, then electrochemical stability is improved, but mechanical integrity and ionic conductivity are insufficient
Solution Approach 1:
The patent combines PEO polymer matrix with cellulose derivatives and lithium salts to create a composite solid polymer electrolyte. The cellulose component provides enhanced mechanical strength and structural integrity, while PEO maintains electrochemical stability and ionic conductivity. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The patent modifies the molecular weight of PEO and adjusts the composition ratios of cellulose derivatives, lithium salts, and plasticizers to optimize both mechanical properties and ionic conductivity. By changing these parameters, the electrolyte achieves sufficient mechanical integrity while maintaining electrochemical stability.
2Reliability
If PEO-based solid polymer electrolytes are used to achieve non-volatility and low flammability, then safety is improved, but power capability is reduced due to concentration polarization
Solution Approach 1:
The patent adjusts the molecular weight of PEO and optimizes the concentration of lithium salts and plasticizer content to reduce concentration polarization. By carefully controlling these parameters, the electrolyte achieves low flammability and non-volatility while improving power capability through enhanced ionic conductivity.
Solution Approach 2:
The patent introduces plasticizers as intermediary substances that facilitate ion transport in the solid polymer electrolyte. These plasticizers reduce the glass transition temperature and increase chain mobility, thereby improving ionic conductivity and power capability without compromising the safety benefits of the solid electrolyte system.
3Ease of manufacture
If conventional PEO-based electrolytes are used to simplify battery production, then ease of manufacture is improved, but mechanical properties and dendrite prevention are insufficient
Solution Approach 1:
The patent creates a composite electrolyte combining PEO with cellulose derivatives that provide superior mechanical properties. The cellulose component forms a robust structural framework that prevents lithium dendrite growth while maintaining the ease of manufacturing associated with PEO-based systems. This composite structure achieves both goals simultaneously.
4Reliability
If LiTFSI salt is used in PEO-based SPEs to achieve good dissociation and solubility, then electrochemical stability is improved, but transference number decreases and concentration polarization increases
Solution Approach 1:
The patent optimizes the concentration of LiTFSI salt and adjusts the molecular weight of PEO to improve cation transference number. By carefully controlling these parameters and adding appropriate plasticizers, the electrolyte achieves good dissociation and solubility while minimizing concentration polarization and enhancing transference number.
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 cellulose-based electrolytes demonstrate improved ionic conductivity and mechanical stability, achieving high transference numbers and stable battery performance, addressing the limitations of previous electrolytes and enhancing the safety and efficiency of lithium and sodium batteries.
Implementation Method 1
cellulose derivative covalently grafted with an anion of an organic sodium or lithium salt, suitable as a solid polymer electrolyte
Data Source
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AI summary
The present invention refers to a method for preparing a solid polymer electrolyte based on modified cellulose, the method comprising the steps of: a) lithiation or sodiation of at least a hydroxyl group of each repeating unit of a "cellulose" to obtain Li(cellulose) or Na(cellulose); b) functionalization of the Li(cellulose) or Na(cellulose) obtained in step a), in the presence of an aprotic solvent by reacting it with an organic linker, wherein the organic linker serves to covalently attach at least one organic salt to the "cellulose", and the use of the solid polymer electrolyte in lithium or sodium secondary batteries.