Na-Ion Battery Electrolyte Composition for High-Temperature Cycle Life
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Solution Overview
Problem
Na-ion batteries face challenges in cycle life and self-discharge, particularly at elevated temperatures, due to differences in electrolyte composition and active materials compared to Li-ion batteries, with existing solutions having limitations in compatibility and commercial availability.
Innovation Solution
A non-aqueous electrolyte composition comprising specific sodium salts, C3-C6 alkyl carbonate solvents, and C2-C6 alkylene carbonate and C1-C8 nitrile additives, such as adiponitrile, is used to enhance cycle life and reduce self-discharge, with a synergistic effect between additives improving overall performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Li-ion electrolyte compositions are used in Na-ion batteries, then the battery can operate with basic ionic conductivity, but the cycle life is reduced and self-discharge increases at elevated temperatures
Solution Approach 1:
The patent modifies the electrolyte composition by changing the concentration parameters of specific additives (VC at 2-10 wt%, ADPN at 0.1-5 wt%) relative to the total electrolyte mass. These parameter changes optimize the formation of protective interphase layers, improving cycle life while reducing self-discharge at elevated temperatures without sacrificing ionic conductivity.
Solution Approach 2:
The patent creates a composite electrolyte system by combining multiple components: cyclic carbonates (EC, PC), linear carbonates (DMC, DEC), and two specific additives (VC and ADPN). This composite composition synergistically forms both SEI and CEI protective layers, resolving the contradiction between reliability and energy loss that cannot be achieved with single-component or conventional Li-ion formulations.
2Reliability
If electrolyte additives are added to improve cell performance and longevity, then the SEI and CEI formation is enhanced, but the electrolyte composition complexity increases
Solution Approach 1:
The patent extracts and focuses on only two critical additives (VC and ADPN) from the broad spectrum of possible electrolyte additives. This selective extraction simplifies the overall composition while maintaining the essential function of forming protective interphase layers, achieving longevity without excessive complexity compared to multi-additive systems.
Solution Approach 2:
The patent defines specific concentration ranges for each component (cyclic carbonate 10-40%, linear carbonate 50-80%, VC 2-10 wt%, ADPN 0.1-5 wt%) to optimize performance. These parameter specifications provide a clear, manageable formulation framework that balances longevity enhancement with compositional simplicity, avoiding the need for complex multi-component additive systems.
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 electrolyte composition significantly improves cycle life and reduces self-discharge at high temperatures, maintaining performance at competitive prices with readily available market solutions.
Implementation Method 1
The electrolyte is thus the media of transport of the cations from one electrode to the other. As such, it is ionically conductive but electronically insulating.
Implementation Method 2
They synergistically decompose/react over the first few cycles of the so-called formation step during the manufacturing process creating the SEI and CEI.
Implementation Method 3
preventing degradation of the electrolyte from reduction/oxidation
Implementation Method 4
preventing degradation of the electrolyte from reduction/oxidation
Data Source
AI summary
A non-aqueous electrolyte composition, which includes (a) at least one sodium salt, (b) at least two C3-C6 alkyl carbonate solvents, and (c) at least two additives chosen from a C2-C6 alkylene carbonate and a C1-C8 nitrile. Also, the cells or the batteries that include this type of non-aqueous electrolyte composition.