Flexible Hybrid Sodium Ion Capacitors from Renewable Electrospun Lignin: Device Manufacture, Performance Testing and Solid Electrolyte Layer Investigations

This project aims to develop a sustainable, environmentally friendly, flexible, Hybrid Sodium Ion Capacitor to support the rapid development of flexible/wearable electronics and sodium ion energy storage technology.

This will be achieved by integrating a flexible hard carbon battery-style anode (higher energy density) and a flexible porous carbon supercapacitor style cathode (higher power density), electrospun from renewable lignin, into one energy storage device.

As a result, this device will deliver higher energy density than flexible supercapacitors, while maintaining high cyclability and power density.These electrodes will be produced under the guidence of Prof.

Titirici, a world-renowned expert in sustainable carbon materials/energy storage.The choice of sodium in this project over lithium is for the following reasons: (i) Na is more abundant and more evenly globally distributed on land (salt, sodium carbonate, and sodium hydroxide) and in salt water, (ii) Al current collectors can be used, instead of Cu in Li, representing a considerable cost saving, and (iii) metal plating of the carbon electrodes occurs less in Na, suggesting that cyclability will be greater with Na than Li.Finally, the fundamentals (solid interface layer, cathodic interlayer) in using Na ions for hybrid capacitors will be examined extensively using laboratory based techniques (XPS and SEM) and synchrotron methods (NEXAFS/XANES).

Understanding the formation of this layer is vital to producing flexible hybrid ion capacitors, as it's formation is one of the leading causes of reduced Coulombic efficiency in batteries resulting in premature failure and poor capacity retention.