Functionalized Polymer Separator Membrane for Transition Metal Trapping
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Solution Overview
Problem
Lithium-ion batteries face issues with capacity fading due to the growth of an unstable Solid Electrolyte Interphase (SEI) layer and the dissolution of transition metal ions from the cathode, leading to anode degradation and reduced charge capacity.
Innovation Solution
A functionalized polymeric separator membrane with a polymer backbone, such as aramid, polyamide, or polyimide, incorporating functional side groups that trap transition metal ions and acidic species, mitigating their impact on the anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional polymeric separator membrane is used, then the battery structure is simple and manufacturing is easy, but transition metal ions dissolve from the cathode and deposit on the anode causing capacity fading
Solution Approach 1:
The patent modifies the chemical parameters of the polymeric separator by introducing functional groups with specific chemical properties (carboxylic acid, phenolic hydroxyl, pyridine, imidazole) that can chemically interact with transition metal ions. This parameter change transforms the membrane from a passive separator to an active trapping medium, resolving the contradiction between maintaining simple structure and preventing metal ion dissolution.
Solution Approach 2:
The patent creates a composite functionalized polymeric separator by combining the base polymeric structure with multiple types of functional groups that have different mechanisms for trapping transition metal ions. This composite approach allows the membrane to simultaneously provide mechanical separation and chemical trapping functions, addressing both the simplicity requirement and the reliability improvement need.
2Loss of substance
If the separator membrane is functionalized with trapping groups, then transition metal ion dissolution is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-functionalizing the polymeric separator membrane with trapping groups before battery assembly. This allows the functional groups to be already in place to immediately trap transition metal ions as they begin to dissolve from the cathode, preventing loss before it occurs. The functionalization is performed as a separate preparatory step that simplifies the overall manufacturing workflow.
Solution Approach 2:
The functionalized polymeric separator acts as an intermediary between the cathode and anode, providing a chemical mediation mechanism to trap transition metal ions. The functional groups on the membrane serve as intermediate trapping sites that capture metal ions before they can migrate to and deposit on the anode, thus reducing metal ion loss without requiring direct modification of the electrode structures.
3Object-affected harmful factors
If functional groups are added to trap acidic species, then anode degradation is mitigated, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing functional groups that perform multiple functions simultaneously. The same functional groups (carboxylic acid, phenolic hydroxyl, pyridine, imidazole) that trap transition metal ions also trap acidic species like HF and H2SO4. This multi-functionality allows a single set of functional groups to address both metal ion dissolution and acidic species degradation, reducing the need for additional specialized components and thereby limiting the increase in device complexity.
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 membrane effectively reduces battery degradation by trapping transition metal ions and acidic species, preventing their deposition on the anode and maintaining charge capacity.
Implementation Method 1
one or more functional side groups capable of trapping transition metal ions and acidic species
Implementation Method 2
one or more functional side groups capable of trapping transition metal ions and acidic species
Data Source
AI summary
A functionalized polymeric separator membrane, including a polymer backbone chosen from an aramid-based polymer, a polyamide-based polymer, or a polyimide-based polymer, or combinations thereof; and further comprising one or more functional side groups (-FSG) capable of trapping transition metal ions and acidic species. The functionalized polymeric separator membrane may be a sulfonated polyaramid separator membrane. Sulfonation of polyaramid separators add functional groups that trap both acidic species and TM ions, thereby suppressing anode damage caused by TM deposition onto the anode by a two-step process. The functionalized polymer separator membranes may be used with Li-ion, Li-metal, or Sodium-ion batteries.