Additive manufacturing enabled, microarchitected, hierarchically porous polylactic-acid/lithium iron phosphate/carbon nanotube nanocomposite electrodes for high performance Li-Ion batteries

The growing need for higher capacity, faster charging-rate, longer cycle-life, and less expensive Li-ion batteries (LIBs) requires architectured cathodes and novel manufacturing strategies. Herein, we report the charge/discharge performance of microarchitected, hierarchically porous nanocomposite cathodes, composed of biodegradable polylactic-acid (PLA)/LiFePO4 (LFP)/carbon nanotube (CNT) enabled by 3D printing. We realize LFP/PLA/CNT cathodes with different CNT loadings (3, 5, 7, and 10 wt%), interconnected porosities (10%, 30%, 50%, and 70%) and thicknesses (100, 200 and 300 μm) by utilizing in-house nanoengineered filaments. The nanocomposite cathodes exhibit a specific capacity of 155 and 127 mAh g−1 and an areal capacity of 1.7 and 4.4 mAh cm−2 for 100 and 300 μm thick electrodes, respectively, at 0.39 mA cm−2. Moreover, we observe that the specific capacity of the thicker electrode (300 μm) enhances from 125 to 151 mAh g−1 without any loss in areal capacity with increase in porosity. The results demonstrate that the effect of thickness on the specific capacity can be negated by engineering desired porosity, and thereby specific and areal capacities can simultaneously be enhanced. The convergence of emerging nanoscale additive manufacturing and the ability to design ever-more-tightly controlled nano- and micro-architected hierarchical structures will enable the creation of high-performance LIBs.