Anion Receptor Additives for Lithium-Ion Battery Electrolytes
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Solution Overview
Problem
High concentrations of anion receptors in non-aqueous electrolytes for lithium-ion batteries improve conductivity but increase impedance, leading to inferior cell performance due to passivation film effects.
Innovation Solution
Using a limited amount of anion receptor additives to dissolve LiF in the passivation films on electrodes, reducing overall impedance and maintaining good conductivity, thereby enhancing power capabilities of lithium-ion cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentrations of anion receptors are used to improve electrolyte conductivity, then conductivity increases, but impedance increases due to passivation film effects
Solution Approach 1:
The patent changes the concentration parameter of anion receptors from high (0.5-1.0 M) to limited amounts (much less than 0.1 M), transforming the role from co-solvent to additive that dissolves LiF in passivation films, thereby reducing impedance while maintaining acceptable conductivity
Solution Approach 2:
The anion receptor acts as an intermediary substance that selectively dissolves LiF in the passivation film on electrode surfaces, mediating between the electrolyte and electrode to reduce interfacial impedance without significantly affecting bulk electrolyte conductivity
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 approach results in lithium-ion cells with improved power performance and cyclability by minimizing anion receptor deposition in passivation films, achieving low impedance and high power capabilities without significant conductivity loss.
Implementation Method 1
an anion receptor is expected to form a complex with the anion of a lithium salt, and hence increase the transference number of lithium ions
Implementation Method 2
use of a limited amount of anion receptor, to dissolve LiF in the passivation films on the electrodes, decreases the overall impedance
Data Source
AI summary
The present invention is generally related to electrolytes containing anion receptor additives to enhance the power capability of lithium-ion batteries. The anion receptor of the present invention is a Lewis acid that can help to dissolve LiF in the passivation films of lithium-ion batteries. Accordingly, one aspect the invention provides electrolytes comprising a lithium salt; a polar aprotic solvent; and an anion receptor additive; and wherein the electrolyte solution is substantially non-aqueous. Further there are provided electrochemical devices employing the electrolyte and methods of making the electrolyte.