Powder extrusion moulding of thick all-ceramic Li4Ti5O12– carbon nanotubes electrodes for high-performance lithium-ion batteries

This work focuses on the development and production of additive-free Li 4 Ti 5 O 12 thick electrodes with carbon nanotubes processed by powder extrusion moulding to be applied as anodes in high energy density lithium-ion batteries. Li 4 Ti 5 O 12 is a safer alternative to graphite, featuring a stable solid electrolyte interphase and minimal lattice parameters changes upon lithiation (“zero-strain” behaviour) though its low conductivity necessitates conductive additives, such as carbon nanotubes. Firstly, the commercial pristine powder in terms of composition, particle size distribution, microstructure, and density was characterized. Rheological analysis identified an optimal 50:50 vol% ratio of powder to binder for extrusion. After shaping, the green parts underwent binder removal and sintering at 850 °C and 900 °C to produce dense, thick electrodes without additional additives. The resulting electrodes were ∼500 μm thick, with porosities of 28.5% (122 mg cm -2 ) and 22.8% (132 mg·cm -2 mass loading), respectively. Electrochemical characterization in coin cells against Li and LiFePO 4 demonstrated excellent performance. In Li 4 Ti 5 O 12 /Li half-cells, volumetric and areal capacities of 375 mA·h·cm -3 and 19 mA·h·cm -2 were achieved at C/24 (0.89 mA·cm -2 ). In full Li 4 Ti 5 O 12 //LiFePO 4 cells, the electrodes showed stable cycling over 80 cycles at C/24, delivering ∼18 mA·h·cm -2 and 350 mA·h·cm -3 , with energy values of ∼ 280 mW·h·g -1 and 35 mW·h·cm -2 . These results highlight the potential of powder extrusion moulding for the scalable fabrication of thick ceramic electrodes with outstanding energy and power densities, paving the way toward next-generation lithium-ion batteries.