Interface-Engineered Atomic Layer Deposition of 3D LiTiO for High-Capacity Lithium-Ion 3D Thin-Film Batteries.

Upcoming energy-autonomous mm-scale Internet-of-things devices require high-energy and high-power microbatteries. On-chip 3D thin-film batteries (TFBs) are the most promising option but lack high-rate anode materials. Here, LiTiO thin films fabricated by atomic layer deposition (ALD) are electrochemically evaluated on 3D substrates for the first time. The 3D LiTiO reveals an excellent footprint capacity of 20.23 µAh cm at 1 C. The outstanding high-rate capability is demonstrated with 7.75 µAh cm at 5 mA cm (250 C) while preserving a remarkable capacity retention of 97.4% after 500 cycles. Planar films with various thicknesses exhibit electrochemical nanoscale effects and are tuned to maximize performance. The developed ALD process enables conformal high-quality spinel (111)-textured LiTiO films on Si substrates with an area enhancement of 9. Interface engineering by employing ultrathin AlO on the current collector facilitates a required crystallization time reduction which ensures high film and interface quality and prospective on-chip integration. This work demonstrates that 3D LiTiO by ALD can be an attractive solution for the microelectronics-compatible fabrication of scalable high-energy and high-power Li-ion 3D TFBs.