Nanofiber Battery Separator for Lithium Supplement Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing composite separators for lithium ion batteries face challenges in maximizing the utilization efficiency of lithium supplementing agents and ensuring the migration of lithium ions, leading to suboptimal initial discharge capacity and battery life due to the hindering effects of inorganic-organic shell layers and pore blockage.
Innovation Solution
A separator with a nanofiber layer containing a lithium supplementing agent, polymer, and optional conductive materials is applied, where the lithium supplementing agent is slowly released to participate in negative electrode film-forming reactions, enhancing electron pathways and maintaining continuous lithium ion migration through a high porosity structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic-organic shell layer is coated on the lithium supplementing agent, then the inner core is isolated from air/oxygen and lithium-rich compound can participate in film-forming reaction, but the shell layer hinders electron conduction path and reduces utilization efficiency of the lithium supplementing agent
Solution Approach 1:
The patent removes the inorganic-organic shell layer from the lithium supplementing agent structure. By extracting this protective coating, the lithium-rich compound is directly exposed to enable efficient electron conduction and participation in oxidation reactions, while the separator substrate and electrolyte provide the necessary protection and reaction environment.
Solution Approach 2:
The patent employs a porous separator substrate with controlled pore structure to replace the dense inorganic-organic shell layer. The porous structure allows electron conduction and lithium ion migration while providing mechanical support and protection, resolving the contradiction between protection and conductivity.
2Quantity of substance
If the surface of separator substrate is coated with lithium supplementing agent layer, then initial discharge capacity is improved, but pores of separator substrate are blocked and migration of lithium ions is hindered
Solution Approach 1:
The patent distributes the lithium supplementing agent uniformly within the porous structure of the separator substrate rather than coating it on the surface. This local distribution ensures that lithium ions can migrate freely through the pores while the lithium supplementing agent is available throughout the separator to enhance discharge capacity.
Solution Approach 2:
The patent utilizes the porous structure of the separator substrate to accommodate the lithium supplementing agent within the pore network. This maintains open pore channels for lithium ion migration while providing sufficient lithium supplementing capability, avoiding pore blockage that would occur with surface coating.
3Quantity of substance
If organic-inorganic shell layer swells/dissolves under electrolyte action, then lithium ions are released to facilitate dissolution of orthosilicate substances, but viscosity of electrolyte increases and migration of lithium ions is hindered
Solution Approach 1:
The patent removes the organic-inorganic shell layer that causes electrolyte viscosity increase upon swelling/dissolution. By extracting this layer, lithium ions are released directly without causing orthosilicate dissolution and viscosity increase, while maintaining controlled release through the porous separator structure.
Solution Approach 2:
The patent changes the release mechanism from chemical dissolution of organic-inorganic shell layer to physical diffusion through porous structure. This parameter change maintains lithium ion release capability while avoiding the harmful side effect of electrolyte viscosity increase.
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 configuration significantly improves the first coulombic efficiency, reduces capacity attenuation, and prolongs battery life by optimizing the utilization of lithium supplementing agents and maintaining electrolyte infiltration, while avoiding adverse effects on electrolyte viscosity.
Implementation Method 1
the nanofiber layer including a lithium supplementing agent, a polymer, and an optional conductive material... the lithium supplementing agent is slowly released
Implementation Method 2
maintaining continuous lithium ion migration through a high porosity structure... while avoiding adverse effects on electrolyte viscosity
Data Source
AI summary
Provided are a separator for a secondary battery and a preparation method therefor, and a secondary battery including the separator, a battery module, a battery pack, and a power consuming device. The separator for a secondary battery of the present application includes a substrate layer and a nanofiber layer provided on one surface of the substrate layer. The nanofiber layer includes a lithium supplementing agent, a polymer, and an optional conductive material; and in the total weight of the nanofiber layer, the content of the lithium supplementing agent accounts for 30.0-50.0% by weight, the content of the polymer accounts for 50.0-70.0% by weight, and the content of the conductive material accounts for 0-5.0% by weight.