High mass loading ultrathick porous Li4Ti5O12 electrodes with improved areal capacity fabricated via low temperature direct writing

Abstract

3D printing has the capability of fabricating highly complex three-dimensional (3D) objects with tailored shapes and geometries, thereby offering an unparalleled tool for the creation of unconventional electrodes for lithium-ion batteries. In this study, high mass loading ultrathick porous Li4Ti5O12 (LTO) electrodes were fabricated via low temperature direct writing for the first time. A LTO ink that was capable of freezing at low temperature was developed and the 3D printing process was optimized to obtain the optimal printing parameters. LTO electrodes with the thickness of ∼200 μm, ∼450 μm and ∼820 μm and the corresponding mass loading of ∼13.3 mg cm−2, 24.1 mg cm−2 and 32.3 mg cm−2 were fabricated. These thick LTO electrodes displayed impressive areal capacities up to ∼4.8 mAh cm−2 @ 0.2 C and ∼3.6 mAh cm−2 @ 2.0 C with the electrode thickness of 820 μm. All the thick electrodes showed excellent rate capacities below the charge/discharge rate of 2.0 C and excellent cycling performance with no deterioration in specific capacities after 100 cycles at 0.5 C. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed that the thick LTO electrodes had excellent reversibility and good kinetics of electrochemical reactions. The major defect of the thick LTO electrodes is the degradation of rate capacities at high charge/discharge rate up to 5.0 C due to the slow kinetics resulted from large thickness.