Opportunity
Lithium-ion batteries (LIBs) are widely used in modern technology due to their high energy density, but they suffer from critical issues such as lithium dendrite formation, thermal instability, and flammability. Dendrites, which grow unevenly during charging cycles, can puncture the separator, leading to short circuits, thermal runaway, and even explosions. Existing solutions, like polypropylene (PP) separators or solid electrolyte interfaces (SEIs), are limited by poor mechanical strength, unstable SEI formation, and complex manufacturing processes. For instance, creating stable SEI layers often requires harsh in-situ conditions, increasing production costs and reducing scalability. Additionally, conventional separators lack flame retardancy, posing safety risks. This patent addresses these challenges by introducing a bifunctional separator that simultaneously regulates dendrite growth and enhances fire resistance, offering a safer and more efficient alternative for next-generation LIBs.
Technology
The patent introduces a novel separator composed of:
1. MXene nanosheets (e.g., Ti₃C₂Tₓ, where Tₓ = –F, –OH, or –O) coated on a
2. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF) framework, embedded with
3. Hydroxyapatite (HAP) nanowires as a flame retardant.
The MXene nanosheets provide lithiophilic surfaces that uniformly distribute Li⁺ ions, suppressing dendrite formation and enabling stable SEI layers rich in LiF. The PVHF framework offers mechanical flexibility and high ionic conductivity, while HAP nanowires act as a physical flame retardant by releasing phosphorus-based radicals (e.g., PO·) under heat. The separator is fabricated via a scalable blade-coating process, where MXene flakes are applied to a pre-formed HAP-PVHF membrane. This design eliminates the need for in-situ SEI formation, simplifies production, and improves battery safety and performance.
Advantages
- Dendrite suppression: MXene’s lithiophilic surface ensures uniform Li deposition, reducing short-circuit risks.
- Flame retardancy: HAP nanowires enhance thermal stability, withstanding >20 seconds in direct flame tests (vs. <1 second for pp separators).
- Mechanical strength: PVHF framework resists puncture from dendrites (45% elongation vs. 10% for PP).
- Electrochemical performance: Enables stable cycling (700 hours at 2 mA/cm²) and high capacity retention (99% after 150 cycles).
- Scalability: Solution-casting and blade-coating methods are cost-effective and industrially viable.
Applications
- High-safety LIBs for electric vehicles (EVs) and aerospace.
- Portable electronics (e.g., smartphones, laptops) requiring long cycle life.
- Grid storage systems where thermal stability is critical.
- Medical devices leveraging non-flammable components.
