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

Heterogeneous, multi-layered electrodes based on high power Li4Ti5O12 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 multilayered electrode, and (ii) the location of the Si layer within the electrode: on the top of the Li4Ti5O12 (closest to the separator), between two layers of Li4Ti5O12 (sandwich configuration) or at the Li4Ti5O12 base (next to the current collector but furthest from the separator). The optimum arrangement of Si spray printed on Li4Ti5O12 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 LiFePO4 cathode. The optimized multilayered electrode was reliably reproduced as a double-sided coating over large area current collectors (>= 20 cm x 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.