Aqueous Battery Electrolyte Design for Safety and Stability
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Solution Overview
Problem
Nonaqueous secondary batteries face safety concerns due to flammability of organic solvents, increased production costs, and high internal resistance, while aqueous lithium-ion batteries suffer from electrolysis issues leading to unstable operation.
Innovation Solution
A battery design using a third aqueous electrolyte with different salt type, concentration, pH, and osmotic pressure between the positive and negative electrodes, preventing electrolyte mixing and maintaining stable ion concentrations, thereby enhancing storage and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If nonaqueous organic solvent electrolyte is used, then high electromotive force (2V to 4.5V) and oxidation resistance are achieved, but safety deteriorates due to flammability of organic solvents
Solution Approach 1:
The patent changes the fundamental parameter of electrolyte composition from nonaqueous organic solvent to aqueous solution, thereby maintaining high electromotive force while eliminating flammability risks. This parameter change allows the battery to achieve both high power output and improved safety by using water-based electrolyte with appropriate pH control and additive packages.
Solution Approach 2:
The patent creates a chemically stable environment by controlling pH and using protective additives in the aqueous electrolyte, effectively creating an 'inert' chemical environment that prevents unwanted reactions while maintaining the benefits of aqueous electrolyte safety.
2Reliability
If nonaqueous organic solvent electrolyte is used, then high oxidation resistance is achieved, but production cost increases due to requirement of dry environment in production process
Solution Approach 1:
The patent changes the electrolyte from nonaqueous to aqueous-based, which fundamentally alters the production environment requirements. Aqueous electrolytes allow for simpler, less costly manufacturing processes that do not require stringent dry environment controls, thereby reducing production costs while maintaining adequate oxidation resistance through pH control and additives.
Solution Approach 2:
The patent employs inexpensive additives and straightforward aqueous electrolyte formulations that can be easily prepared and handled, replacing the need for expensive dry room facilities and specialized handling procedures required for nonaqueous electrolytes.
3Power
If nonaqueous organic solvent electrolyte is used, then high electromotive force is achieved, but internal resistance increases due to inferior conductivity of organic solvent
Solution Approach 1:
The patent changes the electrolyte from organic solvent to aqueous solution, which inherently provides better ionic conductivity. This parameter change reduces internal resistance and improves battery performance while maintaining high electromotive force through appropriate electrode and electrolyte composition design.
4Reliability
If aqueous solution electrolyte is used, then safety is improved and production cost is reduced, but electrolysis occurs leading to unstable operation
Solution Approach 1:
The patent optimizes the pH parameter of the aqueous electrolyte and introduces specific additives that suppress electrolysis reactions. By carefully controlling pH and using appropriate additive packages, the patent maintains operational stability while retaining the safety benefits of aqueous electrolytes.
Solution Approach 2:
The patent converts the potential harm of electrolysis into a beneficial outcome by using controlled electrolysis products and additives that stabilize the system. The electrolysis reactions are managed to produce beneficial effects rather than degradation, thereby maintaining operational 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
The battery achieves improved storage performance and cycle life by maintaining stable electrolyte conditions and preventing electrolyte mixing, reducing the risk of electrolysis and hydrogen generation.
Implementation Method 1
at least one of the type of salt, the concentration of salt, the pH, and the osmotic pressure of the third aqueous electrolyte is different from both those of the first aqueous electrolyte and those of the second aqueous electrolyte
Implementation Method 2
lithium ion insertion/extraction potential of a lithium titanium oxide is about 1.5 V (vs. Li/Li+)
Data Source
Figure 1~2D
Figure 3
Figure 4
AI summary
According to one approach, a battery is provided. The battery includes: a positive electrode; a first aqueous electrolyte held by the positive electrode; a negative electrode; a second aqueous electrolyte held by the negative electrode; at least one separator interposed between the positive electrode and the negative electrode; and a third aqueous electrolyte held by the separator, in which at least one of the type of salt, the concentration of salt, the pH, and the osmotic pressure of the third aqueous electrolyte is different from both those of the first aqueous electrolyte and those of the second aqueous electrolyte.