Sodium-Ion Electrolyte Composition for NaBF4 Solubility and Cycling Stability

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Solution Overview

Problem

Current sodium-ion battery electrolyte compositions face challenges in achieving high ionic conductivity and electrochemical stability due to the low solubility of NaBF4 in organic carbonate-based solvents, which affects the performance and cycling stability of sodium-ion cells, and existing studies on additives are often misleading as they are conducted in sodium-metal half-cells rather than full cells.

Innovation Solution

A non-aqueous electrolyte composition comprising sodium-containing salts and a solvent system with two or more carbonate-based solvents, including tris(trimethylsilyl) borate (TMSB) as a performance additive, which forms a stable cathode-electrolyte interphase and solid-electrolyte interphase, enhancing long-term cycling stability and discharge capacity retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If NaBF4 is used as a cost-effective alternative to NaPF6 in sodium-ion cells, then thermal stability and cost are improved, but solubility in organic carbonate-based solvents deteriorates, resulting in low ionic conductivity

Engineering Contradiction:

Improvethermal stabilityVSAvoidsolubility

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing TMSB additive and using a mixed carbonate solvent system (EC/DMC/EMC) with specific ratios, which improves the solubility of NaBF4 while maintaining thermal stability and achieving adequate ionic conductivity for practical application

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining multiple components: NaBF4 salt, TMSB additive, and a mixture of carbonate solvents (EC, DMC, EMC). This composite approach leverages the synergistic effects of each component to overcome the solubility limitation of NaBF4 while preserving its thermal stability advantages

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional electrolyte compositions are used in sodium-ion cells, then manufacturing simplicity is maintained, but electrochemical performance and cycling stability deteriorate due to low solubility of NaBF4

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcycling stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces TMSB as an intermediary additive that facilitates the dissolution of NaBF4 in carbonate-based solvents. This intermediary substance improves the solubility and ionic conductivity of the electrolyte without significantly complicating the manufacturing process, thereby enhancing cycling stability while maintaining ease of manufacture

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If studies are conducted in sodium-metal half-cells, then experimental simplicity is improved, but measurement accuracy deteriorates as results become misleading and do not reflect full cell performance

Engineering Contradiction:

Improveexperimental simplicityVSAvoidperformance accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs full cell configurations that self-validate the electrolyte performance under realistic operating conditions. By using complete cell assemblies rather than half-cell simplifications, the system provides accurate measurements of electrolyte effectiveness without requiring complex external validation, thereby improving measurement precision while maintaining practical experimental design

Inventive Principle:

Principle #25Self-service

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 proposed electrolyte composition demonstrates improved electrochemical performance and cycling stability in sodium-ion full cells, with enhanced energy retention and reduced total charging times, outperforming control compositions in long-term cycling tests.

Implementation Method 1

tris(trimethylsilyl) borate (TMSB) as a performance additive, which forms a stable cathode-electrolyte interphase and solid-electrolyte interphase

Methodology Applied

Scientific EffectInterphase formation:

Implementation Method 2

High ionic and low electronic conductivities are necessary to maintain cell operation by Na+ transport

Methodology Applied

Scientific EffectIonic conduction:

Implementation Method 3

a non-aqueous electrolyte composition comprising sodium-containing salts and a solvent system which comprises two or more carbonate-based solvents

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentUS20250023104A1Non-aqueous electrolyte compositions

Publication Date: 2025.01.16 FARADION LTD

AI summary

The invention relates to a non-aqueous electrolyte composition having a solvent system which comprises a first component which comprises a first organo carbonate-based solvent and a second organo carbonate-based solvent; and a second component which comprises one or more performance additives that includes tris(trimethylsilyl) borate (TMSB). Devices, methods and uses including electrolytes compositions are also disclosed.