Secondary Battery Separator With Solid Electrolyte Layer
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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 density and long life.
Innovation Solution
A secondary battery design incorporating a porous self-supporting film with a solid electrolyte layer and a polymeric binder, which suppresses water electrolysis and enhances energy density and life by maintaining a high pH at the negative electrode, preventing solvent mixing between electrodes and reducing internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a nonaqueous electrolyte is used, then energy density and charge-discharge efficiency are improved, but safety deteriorates due to combustibility of the solvent
Solution Approach 1:
A porous film is introduced as an intermediary component between the positive and negative electrodes. This film contains pores filled with aqueous electrolyte that act as a mediator to suppress water electrolysis while allowing ion transport. The porous film structure enables it to function as both a physical separator and a chemical barrier against water decomposition, thus improving safety without significantly compromising energy density.
2Reliability
If an aqueous electrolyte is used, then safety is improved by eliminating combustibility, but energy density and charge-discharge efficiency deteriorate due to narrow potential window
Solution Approach 1:
The patent applies local quality by creating different electrolyte environments in different regions of the battery. The porous film contains pores filled with aqueous electrolyte specifically at the separator region where water electrolysis occurs, while the bulk electrolyte can be nonaqueous for high energy density. This localized aqueous environment suppresses water electrolysis without limiting the overall potential window of the battery system.
3Strength
If the separator thickness is increased, then mechanical strength and safety are improved, but internal resistance increases and energy density deteriorates
Solution Approach 1:
The patent employs a porous film as the separator structure. The porous structure provides high mechanical strength and safety while maintaining thin thickness. The pores are filled with aqueous electrolyte that suppresses water electrolysis. The porous structure allows efficient ion transport through the separator, keeping internal resistance low despite the enhanced mechanical protection provided by the porous film structure.
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 energy density and extended life by preventing water electrolysis and enhancing adhesion between active materials and the porous film, while maintaining mechanical strength and reducing internal resistance.
Implementation Method 1
suppresses water electrolysis and enhances energy density and life by maintaining a high pH at the negative electrode
Implementation Method 2
suppresses water electrolysis
Implementation Method 3
preventing solvent mixing between electrodes and reducing internal short circuits
Implementation Method 4
The separator includes a porous self-supporting film, a solid electrolyte layer, and a first binder. The solid electrolyte layer is provided on one main surface of the porous self-supporting film.
Implementation Method 5
The porous self-supported film and the solid electrolyte layer are adhered with the first binder. The first binder exists on both of the one main surface and another main surface of the porous self-supporting film.
Implementation Method 6
The solid electrolyte layer includes solid electrolyte particles and a second binder. The solid electrolyte particles have alkali metal ions conductivity.
Data Source
AI summary
According to one embodiment, a secondary battery is provided. The separator includes a porous self-supporting film, a solid electrolyte layer, and a first binder. The solid electrolyte layer is provided on one main surface of the porous self-supporting film. The porous self-supported film and the solid electrolyte layer are adhered with the first binder. The first binder exists on both of the one main surface and another main surface of the porous self-supporting film. The solid electrolyte layer includes solid electrolyte particles and a second binder. The solid electrolyte particles have alkali metal ions conductivity. The polymeric material of the second bonder is a same as the polymeric material of the first material.