Aqueous Battery Separator Preventing Solvent Permeation
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Solution Overview
Problem
Nonaqueous electrolyte batteries face safety concerns due to combustible solvents, while aqueous electrolyte batteries have limited energy density and low charge-discharge efficiency due to water's narrow potential window, limiting their ability to achieve high energy storage and safety simultaneously.
Innovation Solution
A secondary battery design incorporating a composite separator made of a polymeric material with ion conductive solid electrolyte particles, which prevents solvent permeation and maintains high lithium ion conductivity, ensuring efficient charge and discharge while enhancing safety by controlling pH and preventing water decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nonaqueous electrolyte is used, then charge-and-discharge efficiency and energy density are improved, but safety deteriorates due to combustibility
Solution Approach 1:
Aqueous electrolyte is introduced as an intermediary substance between the positive and negative electrodes, replacing the combustible nonaqueous electrolyte. This mediator enables ion conduction while providing inherent safety through water's non-flammability, thus resolving the contradiction between productivity and safety.
Solution Approach 2:
The electrolyte composition is changed from nonaqueous to aqueous, fundamentally altering the chemical parameters of the battery system. This parameter change maintains safety while the patent addresses efficiency losses through electrode material optimization and electrolyte composition adjustment.
2Object-affected harmful factors
If aqueous electrolyte is used, then safety is improved due to non-combustibility, but energy density and charge-and-discharge efficiency deteriorate due to narrow potential window
Solution Approach 1:
Electrode material parameters are optimized to operate effectively within the aqueous electrolyte's potential window. The patent employs specific positive electrode materials (such as lithium nickel manganese cobalt oxide) and negative electrode materials (such as lithium titanium oxide) with tailored electrochemical properties that maximize energy density while remaining compatible with water-based electrolyte.
Solution Approach 2:
Composite electrode materials and composite electrolyte systems are utilized to enhance performance. The patent combines multiple metal oxides in positive electrodes and uses composite structures in negative electrodes to broaden the operational voltage range and improve capacity, thereby increasing energy density while maintaining safety.
3Object-affected harmful factors
If aqueous electrolyte is used, then safety is improved, but charge-and-discharge efficiency deteriorates due to water electrolysis
Solution Approach 1:
The pH of the aqueous electrolyte is precisely controlled and adjusted to optimize electrochemical performance. By regulating pH parameters and selecting appropriate electrolyte compositions, the patent suppresses water electrolysis reactions while maintaining high ionic conductivity, thus improving charge-and-discharge efficiency without compromising safety.
Solution Approach 2:
The patent implements pH control mechanisms and electrolyte composition management that respond to battery operating conditions. Through feedback control of electrolyte parameters and electrode potentials, water electrolysis is minimized while maintaining efficient ion transport, resolving the contradiction between safety and 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 high charge-and-discharge efficiency, safety, and extended cycle life by preventing solvent mixing and maintaining a high pH within the battery, thus matching the energy density of nonaqueous batteries while ensuring safety.
Implementation Method 1
The composite film has resistance to permeation of an aqueous solvent
Implementation Method 2
ion conductive solid electrolyte particles having alkali metal ions conductivity
Implementation Method 3
a secondary battery includes a positive electrode, a negative electrode, separator, and an aqueous electrolyte
Data Source
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AI summary
According to an approach, a secondary battery (100) is provided. The secondary battery (100) includes a positive electrode (52), a negative electrode (51), separator (53), and an aqueous electrolyte (AE). The separator (53) is located at least between the positive electrode (52) and the negative electrode (51). The separator (53) includes a composite film. The composite film includes a mixture of a polymeric material and ion conductive solid electrolyte particles having alkali metal ions conductivity. The polymeric material includes a polymer comprising a monomer unit. The monomer unit is a hydrocarbon with a functional group including at least one element selected from the group consisting of oxygen (O), sulfur (S), nitrogen (N), and fluorine (F). A ratio of the polymer in the polymeric material is not less than 70 mol%.