Coated Separator Plasma Spray for Lithium-Sulfur Battery
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Solution Overview
Problem
Lithium-sulfur batteries and lithium ion batteries face limited life cycles due to the migration of lithium-polysulfide intermediates and transition metal cations through the porous separator, leading to shuttle effects, decreased sulfur utilization, and capacity fading, which reduces their durability and efficiency.
Innovation Solution
A coated separator is developed using ceramic, cermet, ceramic-electrolyte, or cermet-electrolyte coatings applied via plasma spraying, which acts as a barrier to block polysulfide ions and transition metal cations, preventing their migration and enhancing the battery's capacity and life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a porous separator is used in lithium-sulfur batteries, then lithium ion transport is enabled, but polysulfide migration occurs leading to shuttle effects and reduced battery life
Solution Approach 1:
The patent employs a porous ceramic coating layer on the separator that maintains porosity to allow lithium ion transport while the ceramic material physically blocks polysulfide migration. The porous structure enables ionic conductivity while preventing harmful chemical species from crossing the separator, thus resolving the contradiction between ion transport and battery reliability.
Solution Approach 2:
The separator is constructed as a composite structure combining a base porous polymer separator with a ceramic coating layer (such as alumina, silica, or titania). This composite design integrates the ion-transport capability of the polymer matrix with the blocking properties of the ceramic layer, enabling simultaneous lithium ion permeability and polysulfide rejection.
2Reliability
If a dense coating is applied to block cation migration, then sulfur utilization improves, but ion transport may be hindered
Solution Approach 1:
The ceramic coating is specifically designed with controlled porosity and pore size distribution that allows lithium ions to pass through while blocking larger polysulfide molecules and transition metal cations. The porous structure ensures that the coating does not become a barrier to ion transport while still providing effective blocking functionality.
Solution Approach 2:
The coating structure exhibits local quality variations with different pore sizes, porosity levels, and material compositions at different locations and depths within the coating layer. This gradient structure optimizes ion transport in regions with higher porosity while providing denser blocking regions for cation rejection, thereby balancing transport and utilization.
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 coated separators improve the capacity and useful life of lithium-sulfur and lithium ion batteries by preventing the shuttle effect and polysulfide or metal cation migration, thereby maintaining sulfur utilization and battery durability.
Implementation Method 1
a suspension of i) a ceramic, ii) a cermet, iii) a ceramic with an electrolyte, or iv) a cermet with an electrolyte in a carrier liquid is plasma sprayed without a carrier gas
Data Source
AI summary
In a one-step method for preparing a coated separator, a suspension of i) a ceramic, ii) a cermet, iii) a ceramic with an electrolyte, or iv) a cermet with an electrolyte in a carrier liquid is plasma sprayed without a carrier gas. The carrier liquid is water, alcohol, ethylene glycol, or mixtures thereof.