How to Make Lithium-Sulfur Batteries Last Longer Using Polymer Coatings
A new way to coat sulfur battery cores with a special polymer to prevent them from degrading, helping them hold a charge for more cycles.
Original patent title: “Positive electrode active material for lithium-sulfur battery, preparation method thereof and lithium-sulfur battery comprising same”
A new way to coat sulfur battery cores with a special polymer to prevent them from degrading, helping them hold a charge for more cycles. Granted to Seoul National University R&DB Foundation in 2025 with 20 claims.
Key facts
Coverage
What does this patent actually cover?
This patent describes a way to improve lithium-sulfur batteries by wrapping the sulfur-based core of the battery's positive electrode in a protective shell. The shell is made of a specific material called a polythiophene acetic acid-polyethylene glycol graft copolymer. This shell acts like a sponge that traps lithium polysulfides, which are chemical byproducts that usually leak out and kill the battery's performance. By keeping these chemicals locked inside the shell, the battery stays efficient and lasts through more charge-discharge cycles.
The gap
What does this patent NOT cover?
- Does not cover batteries that do not use a core-shell structure for the active material.
- Does not cover batteries using shell materials other than the specific polythiophene acetic acid-polyethylene glycol graft copolymer.
- Does not cover standard lithium-ion batteries that use metal oxides instead of sulfur compounds in the positive electrode.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation lies in using a graft copolymer that combines the conductive properties of polythiophene with the flexible, trapping nature of polyethylene glycol to create a 'smart' barrier that holds onto sulfur while still allowing electricity to flow.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Experimental high-energy-density lithium-sulfur batteries for electric vehicles
Long-endurance drone battery prototypes
Next-generation portable power storage research
Why it matters
The bigger picture
Lithium-sulfur batteries are highly desirable because they can theoretically store much more energy than standard lithium-ion batteries. However, they have historically suffered from a short lifespan because the sulfur dissolves into the electrolyte. This patent provides a chemical engineering solution to stabilize the sulfur, which is a necessary step for making these batteries commercially viable for electric vehicles or long-range drones.
Filed
August 4, 2021
Granted
April 1, 2025
Market context
Who's building on this
Companies in this space
Research is currently driven by academic institutions like Seoul National University and major battery manufacturers like LG Energy Solution and Samsung SDI, who are actively exploring sulfur-based chemistries to overcome the energy density limits of current lithium-ion technology.
Market impact
This patent contributes to the ongoing effort to transition the energy storage market toward sulfur-based chemistries. By addressing the 'shuttle effect'—the loss of active material that plagues sulfur batteries—it helps move the technology closer to being a practical alternative for high-capacity applications.
Claim 1 — Plain English
What this patent covers
This patent describes a way to improve lithium-sulfur batteries by wrapping the sulfur-based core of the battery's positive electrode in a protective shell. The shell is made of a specific material called a polythiophene acetic acid-polyethylene glycol graft copolymer. This shell acts like a sponge that traps lithium polysulfides, which are chemical byproducts that usually leak out and kill the battery's performance. By keeping these chemicals locked inside the shell, the battery stays efficient and lasts through more charge-discharge cycles.
The clever bit
The innovation lies in using a graft copolymer that combines the conductive properties of polythiophene with the flexible, trapping nature of polyethylene glycol to create a 'smart' barrier that holds onto sulfur while still allowing electricity to flow.
What it does not cover
- Does not cover batteries that do not use a core-shell structure for the active material.
- Does not cover batteries using shell materials other than the specific polythiophene acetic acid-polyethylene glycol graft copolymer.
- Does not cover standard lithium-ion batteries that use metal oxides instead of sulfur compounds in the positive electrode.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
0/40
No citations yet
Claim breadth
13/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
20/20
Granted within 5 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$41K – $131K
Midpoint $82K · 15.1 yr remaining · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
20 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
KOONG, C. Y., Sohn, K., Lee, J., KIM, S., Kim, K., & JEONG, D. (2025). How to Make Lithium-Sulfur Batteries Last Longer Using Polymer Coatings (U.S. Patent No. 12,266,789). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/12266789/merlin-engine
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Make Lithium-Sulfur Batteries Last Longer Using Polymer Coatings cover?
A new way to coat sulfur battery cores with a special polymer to prevent them from degrading, helping them hold a charge for more cycles.
Who owns patent US 12266789?
Seoul National University R&DB Foundation owns this patent, granted in 2025.
When does this patent expire?
This patent is expected to expire on April 1, 2045, when the invention enters the public domain.
What problem does this patent solve?
Lithium-sulfur batteries are highly desirable because they can theoretically store much more energy than standard lithium-ion batteries. However, they have historically suffered from a short lifespan because the sulfur dissolves into the electrolyte. This patent provides a chemical engineering solution to stabilize the sulfur, which is a necessary step for making these batteries commercially viable for electric vehicles or long-range drones.
What does this patent NOT cover?
Does not cover batteries that do not use a core-shell structure for the active material.
Patent monitoring