Aqueous Electrolyte Secondary Battery with Segmented Lithium Concentration
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Solution Overview
Problem
Nonaqueous lithium secondary batteries face safety concerns due to combustible organic solvents, high internal resistance, and limited energy density when using aqueous electrolytes, which are not adequately addressed by existing solutions.
Innovation Solution
A secondary battery design utilizing an aqueous electrolyte with a higher lithium ion concentration in the negative electrode electrolyte and a lower concentration in the positive electrode electrolyte, maintaining a specific ratio to suppress gas generation and enhance charge-discharge efficiency and life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an organic solvent electrolytic solution is used, then high electromotive force and energy density are achieved, but safety deteriorates due to combustibility
Solution Approach 1:
The patent changes the fundamental parameter of electrolyte composition from organic solvent to aqueous solution, thereby fundamentally altering the safety characteristics while maintaining energy density through specific electrode material selection and concentration optimization
Solution Approach 2:
The patent creates an inherently safer environment by using water as the electrolyte solvent, which is non-flammable and provides an inert atmosphere compared to combustible organic solvents, thereby improving safety without requiring additional safety mechanisms
2Reliability
If an aqueous electrolytic solution is used, then safety is improved, but energy density deteriorates due to limited potential range
Solution Approach 1:
The patent optimizes the concentration parameter of lithium ions in the aqueous electrolyte to specific ranges (first electrolyte: 0.1-5.0 mol/L, second electrolyte: 0.5-10.0 mol/L), which enables achieving both safety and sufficient energy density by controlling the electrolyte composition precisely
Solution Approach 2:
The patent divides the electrolyte system into two separate electrolytes with different lithium ion concentrations, allowing each electrolyte to be optimized for its specific electrode interface, thereby achieving both safety and energy density through segmented optimization
3Ease of manufacture
If a single concentration aqueous electrolyte is used, then manufacturing is simplified, but gas generation occurs at electrodes reducing life characteristics
Solution Approach 1:
The patent segments the electrolyte system into two separate electrolytes with different lithium ion concentrations, where the first electrolyte (lower concentration) contacts the positive electrode and the second electrolyte (higher concentration) contacts the negative electrode, preventing gas generation at each electrode interface
Solution Approach 2:
The patent applies different lithium ion concentrations locally at different electrode interfaces - lower concentration at the positive electrode and higher concentration at the negative electrode - optimizing the local chemical environment at each electrode to prevent gas generation while maintaining overall battery performance
4Use of energy by moving object
If lithium titanium oxide is used as negative electrode material with aqueous electrolyte, then theoretical electromotive force of 2.7V is achieved, but gas generation occurs reducing practical efficiency
Solution Approach 1:
The patent changes the lithium ion concentration parameter in the aqueous electrolyte to optimize the electrochemical environment, preventing gas generation at the lithium titanium oxide electrode while maintaining the theoretical 2.7V electromotive force, thereby achieving both high voltage and high efficiency
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 excellent charge-and-discharge efficiency and long life by preventing gas generation in both electrodes, improving safety and energy density compared to traditional nonaqueous batteries.
Implementation Method 1
a first aqueous electrolyte that is in contact with at least part of the positive electrode and contains lithium ions, and a second aqueous electrolyte that is in contact with at least part of the negative electrode and contains lithium ions
Implementation Method 2
The concentration of lithium ions contained in the second aqueous electrolyte is higher than the concentration of lithium ions contained in the first aqueous electrolyte
Data Source
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AI summary
According to one approach, a secondary battery (10) is provided. The secondary battery (10) includes a positive electrode (3), a negative electrode (5), and an aqueous electrolyte. The aqueous electrolyte includes a first aqueous electrolyte (11) and a second aqueous electrolyte (12). The first aqueous electrolyte (11) is in contact with at least part of the positive electrode (3) and contains lithium ions. The second aqueous electrolyte (12) is in contact with at least part of the negative electrode (5) and contains lithium ions. The concentration of lithium ions contained in the second aqueous electrolyte (12) is higher than the concentration of lithium ions contained in the first aqueous electrolyte (11).