Opportunity
The increasing demand for flexible and wearable electronics has highlighted the need for portable energy storage devices that combine high mechanical flexibility with robust energy storage capabilities. Traditional rechargeable batteries, such as lithium-ion batteries, often use rigid metallic current collectors (e.g., copper or stainless steel), which are unsuitable for applications requiring repeated bending or deformation. Existing flexible batteries, which deposit active materials onto substrates like carbon cloth or textiles, exhibit limited recoverability after mechanical stress, leading to irreversible performance degradation. This fragility poses a significant barrier to the development of durable wearable devices, where energy storage systems must withstand frequent deformation without losing functionality. The patent addresses this gap by introducing a zinc-ion battery with inherent shape memory properties, enabling it to restore its original form and electrochemical performance after mechanical stress.
Technology
The patent describes a flexible shape memory yarn battery (SMYB) that integrates shape memory materials with zinc-ion battery technology. The anode is fabricated using a Nickel-Titanium (Nitinol) alloy wire coated with zinc via electrodeposition, leveraging Nitinol’s shape memory effect (SME) to recover from deformation when heated. The cathode consists of stainless steel yarn coated with manganese dioxide (MnO₂) nanocrystallines, further enhanced by a polypyrrole (PPy) coating to improve conductivity and cyclic stability. The battery uses an aqueous gelatin-borax polymer gel electrolyte, which provides ionic conductivity while acting as a mechanical stabilizer. Key innovations include:
- Shape Memory Anode: Nitinol’s SME allows the battery to revert to its original shape after bending, triggered by temperature changes (e.g., immersion in 45°C water).
- Flexible Cathode: The PPy-coated MnO₂ cathode maintains structural integrity during deformation and offers high specific capacity (143.2 mAh/g at 1C).
- Gel Electrolyte: The gelatin-borax matrix improves water retention and ionic conductivity compared to conventional electrolytes, enabling stable performance over 1,000 charge/discharge cycles.
Advantages
- Mechanical Recoverability: Restores shape and 96.8% of capacity after 5 bending-recovery cycles.
- High Flexibility: Operates efficiently at bending angles up to 90° with 79% capacity retention.
- Long Cycle Life: 74.2% capacity retention after 860 cycles at 5C current density.
- Safety: Aqueous electrolyte eliminates risks associated with flammable organic electrolytes.
- Eco-Friendly: Gelatin-borax electrolyte is derived from biodegradable materials.
Applications
- Wearable Electronics: Power sources for smart textiles, health monitors, and flexible displays.
- Medical Devices: Implantable or attachable batteries for biosensors.
- Robotics: Energy storage for soft robotics requiring deformable components.
- Consumer Electronics: Bendable batteries for foldable phones or tablets.
