Localized High Salt Concentration Electrolyte Viscosity Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high salt concentration electrolytes for batteries suffer from high viscosity, which negatively impacts power performance, and there is a lack of understanding about compatible compositions that maintain desirable discharge capacity and capacity retention with varying anodes and cathodes.
Innovation Solution
A battery electrolyte formulation comprising a solvating solvent, diluent, and lithium salt, where the lithium salt is at least 5 times more soluble in the solvating solvent than in the diluent, and the diluent and solvating solvent are present at specific molar ratios, forming a localized high salt concentration electrolyte that mitigates viscosity and enhances electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high salt concentration electrolyte is used, then electrochemical stability and capacity retention are improved, but viscosity increases which deteriorates power performance
Solution Approach 1:
The patent applies parameter changes by adjusting the salt concentration to a specific range (1.8-3.0 M) and modifying the solvent composition ratio (cyclic carbonate 10-40 vol%, chain carbonate 60-90 vol%) to achieve optimal balance between viscosity reduction and electrochemical stability maintenance
Solution Approach 2:
The patent uses a composite electrolyte system combining multiple carbonate solvents (cyclic and chain types) with lithium salt, where the synergistic interaction between different solvent components achieves both low viscosity and high capacity retention without requiring extreme salt concentrations
2Power
If diluent is added to reduce viscosity, then power performance is improved, but discharge capacity and capacity retention may be compromised
Solution Approach 1:
The patent optimizes the diluent concentration parameter within a specific range (60-90 vol% chain carbonate acting as diluent relative to total solvent) to achieve the right balance between viscosity reduction for power performance and maintaining sufficient solvating ability for capacity retention
3Stability of the object's composition
If lithium salt concentration is increased, then ionic concentration gradients are reduced improving deposition uniformity, but viscosity increases affecting battery power
Solution Approach 1:
The patent optimizes lithium salt concentration to 1.8-3.0 M, which is sufficient to reduce ionic concentration gradients and improve deposition uniformity, while avoiding excessive concentrations that would cause unacceptable viscosity increases
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 formulation achieves improved discharge capacity and capacity retention by reducing ionic concentration gradients, minimizing lithium dendrite formation, and maintaining electrochemical stability, with a capacity retention of 80% at 160 cycles or more and a discharge capacity of about 150 mAh/g or more.
Implementation Method 1
essentially all of the solvent molecules are involved in solvating the salt cations
Implementation Method 2
The increased salt concentration also reduces ionic concentration gradients at the electrode, which may be responsible for inhomogeneous lithium deposition during cycling
Implementation Method 3
This enables reduction of the salt anion for solid electrolyte (SEI) formation
Data Source
AI summary
A battery includes an electrolyte comprised of a solvating solvent, diluent, and a lithium salt. The electrolyte is a solution having a saturation point, the lithium salt being at least 5 times more soluble in the solvating solvent than in the diluent. The diluent and the solvating solvent are immiscible at a molar ratio of diluent/solvating solvent of 2 or more, and the solvating solvent and diluent are present in the electrolyte at a diluent/solvating solvent molar ratio of 0.1 to less than 2.