Structure optimization of solvent-free Li4Ti5O12 electrodes by electrostatic spraying for lithium-ion capacitors

The manufacturing processes of electrodes have a prominent influence on the cost and performance of lithium -ion capacitors (LICs), which are limited by the conventional wet-coated method due to the usage of solvent. Herein, the solvent-free Li4Ti5O12 (LTO) electrodes are prepared with electrostatic spraying deposition using for LICs. Owing to the solvent being avoided during the manufacturing, the dry-sprayed electrode exhibits a higher porosity (-40%) than that of the wet-coated electrode (-30%), together with a larger electrochemically active surface area. The optimized microstructure improves electrolyte infiltration and offers effective Li-ion transport paths, which reduces the electrochemical polarization and boosts the specific capacity of the dry-sprayed elec-trode. When the current density increases from 0.5 C to 10 C, the reversible capacity retention of the dry-sprayed electrode is 74%, which is higher than that of the wet-coated electrode (56%). In addition, the powder resistivity of the dry-sprayed electrode decreases sharply by introducing two-dimension (2D) graphene nanoplate (GN) as the conductive agent, thus side effects have been effectively suppressed during the spraying process. As a result, the assembled LICs using the dry-sprayed LTO electrodes show superior energy density and excellent cycling performance, demonstrating this novel fabrication method has practical application prospects.

Automated summary

Solvent-free Li4Ti5O12 (LTO) electrodes were prepared using electrostatic spraying deposition, which exhibited higher porosity and electrochemically active surface area compared to wet-coated electrodes. The optimized microstructure improved electrolyte infiltration and Li-ion transport paths, reducing electrochemical polarization and boosting specific capacity. Introduction of 2D graphene nanoplates as conductive agent decreased powder resistivity and effectively suppressed side effects during spraying process. Assembled LICs using dry-sprayed LTO electrodes showed superior energy density and excellent cycling performance, indicating great potential for practical applications.