Due to the fourth industrial revolution, portable electronic devices and the Internet of Things have rapidly grown, and at the same time, the demand for compact energy storage devices has rapidly increased. Because they must have a high energy density within a confined space, new electrode architectures and materials are of interest. Two-dimensional metal carbides and nitrides, known as MXenes, have shown promising properties in various applications such as energy storage, electromagnetic interference shielding, catalysis, and optoelectronics. In particular, two-dimensional titanium carbide (Ti₃C₂T_x, MXene) has shown excellent energy storage characteristics. In addition, polyaniline can enhance the conductivity of the electrode and has attracted a great deal of attention due to its advantage of being electrochemically active. We report on the layer-by-layer (LbL) assembly of polyaniline nanofiber (PNF) and Ti₃C₂T_x (MXene), hybrid electrodes for electrochemical energy storage devices. We performed three-electrode measurements in the voltage range of 1.5V to 4.0V and obtained reversible electrochemical data of PNF/MXene. Through this, more detailed analysis of charge storage mechanism of PNF and MXene, which make up LbL film, was possible. Not only that, but we also fabricated two-electrode sandwich cells using the prepared PNF/MXene LbL films as a working electrode and a lithium metal ribbon as a counter electrode. The sandwich cell showed a maximum areal capacity of 17.6 μAh cm^-2, a maximum areal energy of 22.1 μWh cm^-2, and a maximum areal power of 1.5 mW cm^-2. This work suggests the possibility of using PNF/MXene LbL electrodes as electrode materials for thin-film energy storage devices for use in future small electronics.

Paraskevi Flouda

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