Layer-by-layer printing of multi-layered heterostructures using Li4Ti5O12 and Si for high power Li-ion storage

Abstract Heterogeneous, multi-layered electrodes based on high power Li 4 Ti 5 O 12 interleaved with a smaller fraction of high capacity Si were fabricated using layer-by-layer spray printing, with the goal of achieving a balance of power and capacity for Li-ion storage technologies. The faradaic charge/discharge behavior of the multi-layered hybrid electrodes was investigated as a function of (i) the thickness of the discrete Si layer within the multi-layered electrode, and (ii) the location of the Si layer within the electrode: on the top of the Li 4 Ti 5 O 12 (closest to the separator), between two layers of Li 4 Ti 5 O 12 (sandwich configuration) or at the Li 4 Ti 5 O 12 base (next to the current collector but furthest from the separator). The optimum arrangement of Si spray printed on Li 4 Ti 5 O 12 offered outstanding electrochemical performance at high current densities of 4000 mA/g and after 500 cycles when in a full Li-ion battery configuration coupled with a spray printed LiFePO 4 cathode. The optimized multi-layered electrode was reliably reproduced as a double-sided coating over large area current collectors (≥20 cm × 15 cm). Sprayed printed electrodes were also readily patterned in-plane as well as through-thickness, offering the prospect for selective additions of high capacity Si or other active or inactive electrode components at specific locations to provide new Li-ion battery performance characteristics.