- Quantification of Efficiency in Lithium Metal Negative Electrodes via Operando X-ray Diffraction CHEMISTRY OF MATERIALS 2021; 33 (18): 7537-7545
- Understanding additive controlled lithium morphology in lithium metal batteries JOURNAL OF MATERIALS CHEMISTRY A 2020; 8 (33): 16960–72
- High Power Energy Storage via Electrochemically Expanded and Hydrated Manganese-Rich Oxides FRONTIERS IN CHEMISTRY 2020; 8
High Power Energy Storage via Electrochemically Expanded and Hydrated Manganese-Rich Oxides.
Frontiers in chemistry
2020; 8: 715
Understanding the materials design features that lead to high power electrochemical energy storage is important for applications from electric vehicles to smart grids. Electrochemical capacitors offer a highly attractive solution for these applications, with energy and power densities between those of batteries and dielectric capacitors. To date, the most common approach to increase the capacitance of electrochemical capacitor materials is to increase their surface area by nanostructuring. However, nanostructured materials have several drawbacks including lower volumetric capacitance. In this work, we present a scalable "top-down" strategy for the synthesis of EC electrode materials by electrochemically expanding micron-scale high temperature-derived layered sodium manganese-rich oxides. We hypothesize that the electrochemical expansion induces two changes to the oxide that result in a promising electrochemical capacitor material: (1) interlayer hydration, which improves the interlayer diffusion kinetics and buffers intercalation-induced structural changes, and (2) particle expansion, which significantly improves electrode integrity and volumetric capacitance. When compared with a commercially available activated carbon for electrochemical capacitors, the expanded materials have higher volumetric capacitance at charge/discharge timescales of up to 40 s. This shows that expanded and hydrated manganese-rich oxide powders are viable candidates for electrochemical capacitor electrodes.
View details for DOI 10.3389/fchem.2020.00715
View details for PubMedID 32974280
View details for PubMedCentralID PMC7461800
- Confined Interlayer Water Promotes Structural Stability for High-Rate Electrochemical Proton Intercalation in Tungsten Oxide Hydrates ACS ENERGY LETTERS 2019; 4 (12): 2805–12
- Analysis and Simulation of One-Dimensional Transport Models for Lithium Symmetric Cells ELECTROCHEMICAL SOC INC. 2019: A3806–A3819
Novel ALD Chemistry Enabled Low-Temperature Synthesis of Lithium Fluoride Coatings for Durable Lithium Anodes
ACS APPLIED MATERIALS & INTERFACES
2018; 10 (32): 26972–81
Lithium metal anodes can largely enhance the energy density of rechargeable batteries because of the high theoretical capacity and the high negative potential. However, the problem of lithium dendrite formation and low Coulombic efficiency (CE) during electrochemical cycling must be solved before lithium anodes can be widely deployed. Herein, a new atomic layer deposition (ALD) chemistry to realize the low-temperature synthesis of homogeneous and stoichiometric lithium fluoride (LiF) is reported, which then for the first time, as far as we know, is deposited directly onto lithium metal. The LiF preparation is performed at 150 °C yielding 0.8 Å/cycle. The LiF films are found to be crystalline, highly conformal, and stoichiometric with purity levels >99%. Nanoindentation measurements demonstrate the LiF achieving a shear modulus of 58 GPa, 7 times higher than the sufficient value to resist lithium dendrites. When used as the protective coating on lithium, it enables a stable Coulombic efficiency as high as 99.5% for over 170 cycles, about 4 times longer than that of bare lithium anodes. The remarkable battery performance is attributed to the nanosized LiF that serves two critical functions simultaneously: (1) the high dielectric value creates a uniform current distribution for excellent lithium stripping/plating and ultrahigh mechanical strength to suppress lithium dendrites; (2) the great stability and electrolyte isolation by the pure LiF on lithium prevents parasitic reactions for a much improved CE. This new ALD chemistry for conformal LiF not only offers a promising avenue to implement lithium metal anodes for high-capacity batteries but also paves the way for future studies to investigate failure and evolution mechanisms of solid electrolyte interphase (SEI) using our LiF on anodes such as graphite, silicon, and lithium.
View details for PubMedID 29986134