Textile actuators based on electrochemical lithiation of silicon thin films

The aim of this study was to investigate whether a textile electrode coated with an amorphous silicon thin film can be used as an actuator element in a lithium electrolysis process in comparison to a crysralline silicon wafer stripe. It is well known from battery research that a deformation of the silicon electrode occurs during lithiation. This reversible process is being studied as a mechanical switch to move lightweight textiles for potential applications such as ventilation, thermal management, privacy protection, etc. To identify a solution, silicon thin film coatings on textile substrates, electrolytes and the lithiation process have been examined under both inert laboratory and application conditions. Methods such as cyclic voltammetry, amperometry and impedance spectroscopy were used to analyze the electrolytic process, and secondary ion mass spectrometry and electrical analysis were used to obtain material information. It is shown that the charging and discharging of lithium ions is associated with bending for more than 5 cycles. During this process, repeated forward and backward movements of the textile electrode were observed at low voltages below −10 V. Bending forces in the range of 0.2–0.7 mN dependent on the charging time, and a current flow in the range of −0.01 to −440 µA dependent on the voltage, were measured. This is suitable for the scenario where low force is required.