RESUMO
Epitaxial cathodes in lithium-ion microbatteries are ideal model systems to understand mass and charge transfer across interfaces, plus interphase degradation processes during cycling. Importantly, if grown at <450 °C, they also offer potential for complementary metal-oxide-semiconductor (CMOS) compatible microbatteries for the Internet of Things, flexible electronics, and MedTech devices. Currently, prominent epitaxial cathodes are grown at high temperatures (>600 °C), which imposes both manufacturing and scale-up challenges. Herein, we report structural and electrochemical studies of epitaxial LiMn2O4 (LMO) thin films grown on a new current collector material, NiCo2O4 (NCO). We achieve this at the low temperature of 360 °C, â¼200 °C lower than existing current collectors SrRuO3 and LaNiO3. Our films achieve a discharge capacity of >100 mAh g-1 for â¼6000 cycles with distinct LMO redox signatures, demonstrating long-term electrochemical stability of our NCO current collector. Hence, we show a route toward high-performance microbatteries for a range of miniaturized electronic devices.
RESUMO
This work reveals that photoanodes based on TiNb2 O7 (TNO) powder show remarkable water-oxidation properties including nearly ideal charge-transfer and charge-injection efficiencies. Furthermore, using a simplified photoanode construction and carefully surveying the structural and morphological characteristics of oriented and polycrystalline thin films and powder-based samples revealed that the water-splitting kinetics of TNO is negligibly effected by surface morphology; instead, internal grain boundaries likely play a driving role. The current powder-based TNO photoanodes exhibit ideal water-oxidation kinetics and oxidize water at minimal applied biases under illumination; consequently, TNO exhibits an early onset photocurrent voltage (0.4â V vs. RHE) that rivals that of other state-of-the-art photoanode materials.
