Opportunity
The rapid development of flexible and wearable electronics has created a growing demand for safe, high-capacity, and durable energy storage solutions. Current batteries, such as lithium-ion batteries, often face challenges related to toxicity, flammability, and limited capacity retention under mechanical stress or harsh environmental conditions. Zinc-ion batteries (ZIBs) have emerged as a promising alternative due to their lower cost, higher safety, and multi-electron transfer capabilities. However, existing ZIBs still suffer from cathode instability during cycling, leading to capacity degradation and poor long-term performance. Additionally, flexible/wearable devices require energy storage solutions that can withstand bending, twisting, and extreme temperatures while maintaining electrochemical stability. This patent addresses these challenges by introducing a novel energy storage device with a vanadium carbide MXenes cathode and a gelatin-based electrolyte, offering high capacity, prolonged cycling life, and exceptional mechanical and environmental resilience.
Technology
The patent introduces an innovative energy storage device comprising:
- Cathode: A vanadium carbide MXenes (V₂CT) material with a layered structure that undergoes physical and chemical transformations during charging/discharging cycles. The MXenes structure delaminates into fewer layers, increasing active sites for ion insertion, and partially transitions into vanadium oxide (V₂O) and carbon phases, enhancing capacity.
- Anode: A flexible zinc anode electrodeposited on a carbon cloth substrate, providing high conductivity and mechanical stability.
Electrolyte: A gelatin-based hydrogel (e.g., polyacrylamide) containing a high-concentration aqueous salt solution (e.g., 5–21 M LiTFSI + Zn(CFSO)₂). This electrolyte prevents cathode dissolution, stabilizes the MXenes structure, and enables operation under water or at temperatures as low as −20°C.
The key innovation lies in the self-optimizing cathode mechanism:
- During cycling, Zn²⁺ ions insert into the MXenes interlayer spacings, causing structural expansion and delamination, which exposes more active sites.
- Simultaneously, the V₂CT partially oxidizes to V₂O, increasing vanadium’s valence states (V³⁺, V⁴⁺, V⁵⁺) and boosting charge storage.
- The high-concentration electrolyte suppresses unwanted side reactions, ensuring long-term stability (over 18,000 cycles).
Advantages
- High Capacity: Delivers 508 mAh/g at 0.2 A/g, surpassing conventional ZIBs.
- Long Cycle Life: Stable for over 18,000 cycles at 10 A/g with 100% Coulombic efficiency.
- Mechanical Flexibility: Operates under bending (180°), twisting (360°), cutting, and stabbing.
- Environmental Resilience: Functions underwater and at temperatures as low as −20°C.
- Cost-Effective: Assembly does not require oxygen-free/water-free environments.
Applications
- Wearable Electronics: Power sources for smart fabrics, health monitors, and flexible displays.
- Electric Vehicles: High-energy-density batteries for EVs and hybrid systems.
- Extreme Environments: Devices for aerospace, military, or polar research.
- Grid Storage: Scalable solutions for renewable energy storage.
