Continuously 3D printed quantum dot-based electrodes for lithium storage with ultrahigh capacities

Although 3D printing has been explored to construct various well-designed architectures for energy storage, it is still stagnated by poor electrochemical performance owing to the slow kinetics for both electron and ion diffusion. Here, ultra-fine and mono-disperse SnO₂ quantum dots (QDs) with sizes of 2-4 nm were produced on a large scale through a facile controllable sol-gel approach, affording a favorable QD-based printable ink for continuous 3D printing without clogging. Remarkably enough, the 3D printed QD-based microelectrode exhibits an ultrahigh specific capacity of 991.6 mA h g^-1 (4 layers), high areal capacity and good rate capability. This superior electrochemical performance is attributed to the favorable kinetics for both electrons and ions in the 3D printed SnO₂ QD-based microelectrode. This work provides an efficient, green and scalable route to apply 3D printing in the area of rechargeable microbatteries.