The application of nanocellulose in flexible batteries: opening a new era of green energy

Against the backdrop of rapid development of wearable electronic devices, smart textiles, bendable displays and flexible energy storage systems, traditional rigid batteries can no longer meet the multiple needs of lightness, deformability, environmental protection and high performance. Flexible batteries are born as the next generation of energy carriers. Nanocellulose , due to its unique structure and performance, is becoming one of the new materials for building key components of flexible batteries.

1. Advantages of nanocellulose adapt to flexible batteries

Attribute Features	Contribution to flexible batteries
High flexibility	Ensure the battery operates stably in bending and stretching states
Renewable and biodegradable	Green and environmentally friendly to reduce the impact of electronic waste on the environment
High specific surface area and porous structure	Provides more active sites that facilitate ion / electron transport
Rich surface functional groups	Easy to chemically modify or composite conductive materials
Excellent film forming properties	Can be used as an electrolyte carrier, current collector or separator material

2. The key application parts of nanocellulose in flexible batteries

1. Flexible electrode support material

Nanocellulose can be used as a supporting substrate for electrode active materials. By composited with graphene, carbon nanotubes, conductive polymers (such as PEDOT:PSS ), etc., it can build electrode materials with high conductivity, strong flexibility and good mechanical stability.

For example:

Nanocellulose / graphene paper: used in lithium-ion battery cathodes, with excellent curling and conductive properties.

Nanocellulose / carbon nanotube network membrane: can be used to prepare high-energy density, stretchable supercapacitor electrodes.

2. Flexible battery separator material

Nanocellulose has excellent thermal stability and mechanical strength and can be used as a separator for lithium batteries or lithium ion capacitors. Compared with traditional polyolefin separators (such as PE 、PP ):

Not easy to shrink heat and is safer;

The porous structure promotes electrolyte adsorption and enhances ion mobility;

The surface can be further oxidized (such as TEMPO oxidation) to improve hydrophilicity and electrical conductivity.

3. Solid state / gel electrolyte carrier

Nanocellulose can also serve as a carrier matrix for solid electrolytes, loading liquid or gel electrolytes to form a new flexible and safe electrolyte layer. By crosslinking or composite polymers, it is possible to:

Better ionic conductivity;

Stronger shape retention;

Lower leakage risk.

4. Overall flexible battery substrate

Using the film-forming properties of nanocellulose, it can be used as the shell / base material of the entire battery. It is not only lightweight, but also has certain barrier properties and mechanical protection properties, and is expected to replace conventional substrates such as plastics and metals in wearable devices.

3. Representative research results and practical cases

Research cases	illustrate
CNC/ graphene electrodes are used in lithium-ion batteries	Up to 120 mAh/g capacity, retention rate exceeds 90% after circulation , good flexibility
TEMPO oxidized CNF diaphragm replaces PE membrane	Shows higher thermal stability ( >200°C ) and better electrolyte wetting
Nanocellulose /PVA/ Salt-based gel electrolyte	Used for zinc ion flexible batteries, the battery can 180be more than the bend, and the performance does not decrease significantly
Nanocellulose -carbon material -polymer three-phase composite flexible electrode	Achieve high power density ( >1W/cm² ) and good self-healing ability

4. Challenges and development directions

Although nanocellulose has broad application prospects in flexible batteries, the following problems still need to be overcome:

Difficulty in large-scale preparation: the stable and low-cost preparation of high-purity nanocellulose materials is still the bottleneck;

Inadequate conductivity: natural cellulose is not conductive, and conductive materials need to be introduced or modified;

Electrochemical stability: The electrochemical stability of materials needs to be strengthened during long-term use.

Future development direction:

Build multifunctional composite materials: combined with conductive polymers, MXene , metal nanoparticles, etc.;

Green process optimization: Developing low-energy consumption and low-pollution nanocellulose preparation technology;

Smart battery applications: such as self-healing batteries, wearable energy storage systems, biocompatible batteries, etc.

Conclusion

Nanocellulose provides a new solution for flexible battery materials with its green, flexible and diverse characteristics. It not only promotes the development of lightweight and wearable energy devices, but also lays the foundation for achieving sustainable electronic manufacturing. With the continuous breakthroughs in materials science and nanotechnology, future flexible energy equipment will be more environmentally friendly, efficient and close to our daily lives.