Steric Effect Tuned Ion Solvation Enabling Stable Cycling of High-Voltage Lithium Metal Battery.
Journal of the American Chemical Society
1,2-Dimethoxyethane (DME) is a common electrolyte solvent for lithium metal batteries. Various DME-based electrolyte designs have improved long-term cyclability of high-voltage full cells. However, insufficient Coulombic efficiency at the Li anode and poor high-voltage stability remain a challenge for DME electrolytes. Here, we report a molecular design principle that utilizes a steric hindrance effect to tune the solvation structures of Li+ ions. We hypothesized that by substituting the methoxy groups on DME with larger-sized ethoxy groups, the resulting 1,2-diethoxyethane (DEE) should have a weaker solvation ability and consequently more anion-rich inner solvation shells, both of which enhance interfacial stability at the cathode and anode. Experimental and computational evidence indicates such steric-effect-based design leads to an appreciable improvement in electrochemical stability of lithium bis(fluorosulfonyl)imide (LiFSI)/DEE electrolytes. Under stringent full-cell conditions of 4.8 mAh cm-2 NMC811, 50 mum thin Li, and high cutoff voltage at 4.4 V, 4 M LiFSI/DEE enabled 182 cycles until 80% capacity retention while 4 M LiFSI/DME only achieved 94 cycles. This work points out a promising path toward the molecular design of non-fluorinated ether-based electrolyte solvents for practical high-voltage Li metal batteries.
View details for DOI 10.1021/jacs.1c09006
View details for PubMedID 34709034
- A Nickel-Decorated Carbon Flower/Sulfur Cathode for Lean-Electrolyte Lithium-Sulfur Batteries ADVANCED ENERGY MATERIALS 2021
High-frequency and intrinsically stretchable polymer diodes.
2021; 600 (7888): 246-252
Skin-like intrinsically stretchable soft electronic devices are essential to realize next-generation remote and preventative medicine for advanced personal healthcare1-4. The recent development of intrinsically stretchable conductors and semiconductors has enabled highly mechanically robust and skin-conformable electronic circuits or optoelectronic devices2,5-10. However, their operating frequencies have been limited to less than 100hertz, which is much lower than that required for many applications. Here we report intrinsically stretchable diodes-based on stretchable organic and nanomaterials-capable of operating at a frequency as high as 13.56megahertz. This operating frequency is high enough for the wireless operation of soft sensors and electrochromicdisplaypixels using radiofrequency identification in which the base-carrier frequency is 6.78megahertz or13.56megahertz. This was achieved through a combination of rational material design and device engineering. Specifically, we developed a stretchable anode, cathode, semiconductor and current collector that can satisfy the strict requirements for high-frequency operation. Finally, we show the operational feasibility of our diode by integrating it with a stretchable sensor, electrochromicdisplay pixel and antenna to realize a stretchable wireless tag. This work is an important step towards enabling enhanced functionalities and capabilities for skin-like wearable electronics.
View details for DOI 10.1038/s41586-021-04053-6
View details for PubMedID 34880427
A Cation-Tethered Flowable Polymeric Interface for Enabling Stable Deposition of Metallic Lithium.
Journal of the American Chemical Society
A fundamental challenge, shared across many energy storage devices, is the complexity of electrochemistry at the electrode-electrolyte interfaces that impacts the Coulombic efficiency, operational rate capability, and lifetime. Specifically, in energy-dense lithium metal batteries, the charging/discharging process results in structural heterogeneities of the metal anode, leading to battery failure by short-circuit and capacity fade. In this work, we take advantage of organic cations with lower reduction potential than lithium to build an electrically responsive polymer interface that not only adapts to morphological perturbations during electrodeposition and stripping but also modulates the lithium ion migration pathways to eliminate surface roughening. We find that this concept can enable prolonging the long-term cycling of a high-voltage lithium metal battery by at least twofold compared to bare lithium metal.
View details for DOI 10.1021/jacs.0c09649
View details for PubMedID 33314926
- Dense Carbon Nanoflower Pellets for Methane Storage ACS APPLIED NANO MATERIALS 2020; 3 (8): 8278–85
- A Carbon Flower Based Flexible Pressure Sensor Made from Large-Area Coating ADVANCED MATERIALS INTERFACES 2020
- F4-TCNQ as an Additive to Impart Stretchable Semiconductors with High Mobility and Stability ADVANCED ELECTRONIC MATERIALS 2020
- On-demand production of hydrogen by reacting porous silicon nanowires with water NANO RESEARCH 2020