Aqueous Electrolyte Metal Cation Anode Protection
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Solution Overview
Problem
Aqueous lithium ion secondary batteries using high-concentration aqueous electrolyte solutions face challenges with electrolysis on the anode surface due to overvoltage, leading to unstable charge/discharge cycles.
Innovation Solution
An aqueous electrolyte solution comprising water, a lithium ion, at least one imide-based anion (TFSI or FSI), and a metal cation, with specific concentrations and pH levels, is used to suppress electrolysis by electrodeposition of metal cations with low work functions on the anode surface, reducing direct contact between the electrolyte and high-work-function areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high-concentration aqueous electrolyte solution is used, then potential window range is expanded, but electrolysis occurs on anode surface due to overvoltage
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific metal cations (Mg2+, Ca2+, Sr2+, Ba2+) at controlled concentrations (0.001-0.1 mol/kg) into the high-concentration aqueous electrolyte. This parameter modification suppresses electrolysis on the anode surface while preserving the expanded potential window, thereby resolving the contradiction between adaptability and reliability
Solution Approach 2:
The metal cations act as intermediary substances that mediate between the high-concentration electrolyte and the anode surface. These cations preferentially adsorb on the anode surface, forming a protective layer that prevents direct contact between the electrolyte and anode, thus suppressing electrolysis reactions while allowing the high-concentration electrolyte to maintain its expanded potential window
2Quantity of substance
If high-concentration aqueous electrolyte solution is used, then energy density per volume is improved, but charge/discharge cycles become unstable
Solution Approach 1:
The patent modifies the electrolyte composition by adding specific metal cations at optimized concentrations to the high-concentration aqueous electrolyte. This parameter change suppresses electrolysis side reactions that degrade cycle stability, allowing the battery to maintain both high energy density and stable charge/discharge cycles
Solution Approach 2:
The metal cations serve as intermediary substances that stabilize the interface between the electrolyte and anode. By preferentially adsorbing on the anode surface, they prevent direct electrolysis of the high-concentration electrolyte, thereby preserving both the high energy density and cycle stability
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
This approach stabilizes charge/discharge cycles and improves the cycle characteristics of aqueous lithium ion secondary batteries by reducing electrolysis on the anode surface, enhancing the battery's performance and longevity.
Implementation Method 1
electrodeposition of metal cations with low work functions on the anode surface
Implementation Method 2
there is a case where an aqueous electrolyte solution is electrolyzed on a surface of an anode due to overvoltage etc.
Data Source
Figure 1
Figure 2A~2F
Figure 3A~3D
AI summary
Electrolysis of an aqueous electrolyte solution on a surface of an anode is suppressed when an aqueous lithium ion secondary battery is charged/discharged. In an aqueous electrolyte solution that is used for an aqueous lithium ion secondary battery, at least one metal cation selected from an aluminum ion, a titanium ion, a manganese ion, a zinc ion, a gallium ion, a yttrium ion, a zirconium ion, an indium ion, a lanthanum ion, a cerium ion, a neodymium ion, and a hafnium ion is contained so that its content is more than 0 mol and no more than 0.01 mol per kilogram of the aqueous electrolyte solution, in addition to a lithium ion and at least one imide based anion.