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1. Three-dimensional Zn-based alloys for dendrite-free aqueous Zn battery in dual-cation electrolytes

   https://doi.org/10.1038/s41467-022-35618-2  

   Tian, Huajun ; Feng, Guangxia ; Wang, Qi ; Li, Zhao ; Zhang, Wei ; Lucero, Marcos ; Feng, Zhenxing ; Wang, Zi-Le ; Zhang, Yuning ; Zhen, Cheng ; et al ( December 2022 , Nature Communications)

   Aqueous zinc-ion batteries, in terms of integration with high safety, environmental benignity, and low cost, have attracted much attention for powering electronic devices and storage systems. However, the interface instability issues at the Zn anode caused by detrimental side reactions such as dendrite growth, hydrogen evolution, and metal corrosion at the solid (anode)/liquid (electrolyte) interface impede their practical applications in the fields requiring long-term performance persistence. Despite the rapid progress in suppressing the side reactions at the materials interface, the mechanism of ion storage and dendrite formation in practical aqueous zinc-ion batteries with dual-cation aqueous electrolytes is still unclear. Herein, we design an interface material consisting of forest-like three-dimensional zinc-copper alloy with engineered surfaces to explore the Zn plating/stripping mode in dual-cation electrolytes. The three-dimensional nanostructured surface of zinc-copper alloy is demonstrated to be in favor of effectively regulating the reaction kinetics of Zn plating/stripping processes. The developed interface materials suppress the dendrite growth on the anode surface towards high-performance persistent aqueous zinc-ion batteries in the aqueous electrolytes containing single and dual cations. This work remarkably enhances the fundamental understanding of dual-cation intercalation chemistry in aqueous electrochemical systems and provides a guide for exploring high-performance aqueous zinc-ion batteries andmore »beyond.

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2. Influence of intrinsic defects on the structure and dynamics of the mixed Pb–Sn perovskite: first-principles DFT and NAMD simulations

   https://doi.org/10.1039/d1ta09027e  

   Liu, Qi ; Li, Akang ; Chu, Weibin ; Prezhdo, Oleg V. ; Liang, WanZhen ( December 2021 , Journal of Materials Chemistry A)

   The mixed tin (Sn) and lead (Pb) perovskite compositions have shown great potential in perovskite photovoltaic devices due to the significantly enhanced material stability and prolonged carrier lifetime, compared to the pure Sn halide perovskites. In spite of the increasing interest, the behaviors of photo-generated charges and of the intrinsic point defects, such as the metal cation vacancies (V Sn and V Pb ) and the interstitial halogen (i I ), have not been well understood in this class of materials. We report first-principles density functional theory (DFT) calculations combined with ab initio non-adiabatic molecular dynamics (NAMD) simulations on the static and dynamic structures of MA 2 SnPbI 6 with and without these intrinsic defects. We discuss the nature of the defect states and unveil the influence of the intrinsic point defects on the structure, optoelectronic properties, and charge carrier dynamics of MA 2 SnPbI 6 . The i I defect significantly shortens the carrier lifetime by creating mid-gap states that provide new recombination pathways. In comparison, the vacancy defects have much weaker influence on the carrier lifetime. Both V Sn and V Pb produce the defect states just below the valence band maxima (VBMs), and do not alter themore »band gap. They affect the carrier lifetime through changing the energy dispersions of VBMs and the conduction band minima (CBMs). We suggest that excess cations should be used in the synthesis of perovskites to avoid the appearance of interstitial halogen defects.« less
3. Hydrogen bonding steers the product selectivity of electrocatalytic CO reduction

   https://doi.org/10.1073/pnas.1900761116  

   Li, Jingyi ; Li, Xiang ; Gunathunge, Charuni M. ; Waegele, Matthias M. ( April 2019 , Proceedings of the National Academy of Sciences)

   The product selectivity of many heterogeneous electrocatalytic processes is profoundly affected by the liquid side of the electrocatalytic interface. The electrocatalytic reduction of CO to hydrocarbons on Cu electrodes is a prototypical example of such a process. However, probing the interactions of surface-bound intermediates with their liquid reaction environment poses a formidable experimental challenge. As a result, the molecular origins of the dependence of the product selectivity on the characteristics of the electrolyte are still poorly understood. Herein, we examined the chemical and electrostatic interactions of surface-adsorbed CO with its liquid reaction environment. Using a series of quaternary alkyl ammonium cations (${\mathrm{m}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$,${\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$,${\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$, and${\mathrm{b}\mathrm{u}\mathrm{t}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$), we systematically tuned the properties of this environment. With differential electrochemical mass spectrometry (DEMS), we show that ethylene is produced in the presence of${\mathrm{m}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$and${\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$cations, whereas this product is not synthesized in${\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{p}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$- and${\mathrm{b}\mathrm{u}\mathrm{t}\mathrm{y}\mathrm{l}}_4{\mathrm{N}}^{+}$-containing electrolytes. Surface-enhanced infrared absorption spectroscopymore »(SEIRAS) reveals that the cations do not block CO adsorption sites and that the cation-dependent interfacial electric field is too small to account for the observed changes in selectivity. However, SEIRAS shows that an intermolecular interaction between surface-adsorbed CO and interfacial water is disrupted in the presence of the two larger cations. This observation suggests that this interaction promotes the hydrogenation of surface-bound CO to ethylene. Our study provides a critical molecular-level insight into how interactions of surface species with the liquid reaction environment control the selectivity of this complex electrocatalytic process.

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4. Emerging investigator series: first-principles and thermodynamics comparison of compositionally-tuned delafossites: cation release from the (001) surface of complex metal oxides

   https://doi.org/10.1039/C9EN01304K  

   Bennett, Joseph W. ; Jones, Diamond T. ; Hudson, Blake G. ; Melendez-Rivera, Joshua ; Hamers, Robert J. ; Mason, Sara E. ( June 2020 , Environmental Science: Nano)

   Nanoscale complex metal oxides have transformed how technology is used around the world. A ubiquitous example is the class of electroreactive cathodes used in Li-ion batteries, found in portable electronics and electric cars. Lack of recycling infrastructure and financial drivers contribute to improper disposal, and ultimately, introduction of these materials into the environment. Outside of sealed operational conditions, it has been demonstrated that complex metal oxides can transform in the environment, and cause negative biological impact through leaching of cations into aqueous phases. Using a combined DFT and thermodynamics methodology, insights into the mechanism and driving forces of cation release can be studied at the molecular-level. Here, we describe design principles that can be drawn from previous collaborative research on complex metal oxide dissolution of the Li(Ni y Mn z Co 1−y−z )O 2 family of materials, and go on to posit ternary complex metal oxides in the delafossite structure type with controlled release behavior. Using equistoichiometric formulations in the delfossite structure, we use DFT and thermodynamics to model cation release. The release trends are discussed in terms of lattice stability, solution chemistry/solubility limits, and electronic/magnetic properties. Intercalation voltages are calculated and discussed as a predictive metric for potential functionalitymore »of the model materials.« less
5. Catalyzing zinc-ion intercalation in hydrated vanadates for aqueous zinc-ion batteries

   https://doi.org/10.1039/D0TA01468K  

   Liu, Chaofeng ; Tian, Meng ; Wang, Mingshan ; Zheng, Jiqi ; Wang, Shuhua ; Yan, Mengyu ; Wang, Zhaojie ; Yin, Zhengmao ; Yang, Jihui ; Cao, Guozhong ( April 2020 , Journal of Materials Chemistry A)

   Hydrated vanadium pentoxide (VOH) can deliver a gravimetric capacity as high as 400 mA h g −1 owing to the variable valence states of the V cation from 5+ to 3+ in an aqueous zinc ion battery. The incorporation of divalent transition metal cations has been demonstrated to overcome the structural instability, sluggish kinetics, fast capacity degradation, and serious polarization. The current study reveals that the catalytic effects of transition metal cations are probably the key to the significantly improved electrochemical properties and battery performance because of the higher covalent character of 55% in the Cu–O bond in comparison with 32% in the Mg–O bond in the respective samples. Cu( ii ) pre-inserted VOH (CuVOH) possesses a significantly enhanced intercalation storage capacity, an increased discharge voltage, great transport properties, and reduced polarization, while both VOH and Mg( ii ) pre-inserted VOH (MgVOH) demonstrate similar electrochemical properties and performances, indicating that the incorporation of Mg cations has little or no impact. For example, CuVOH has a redox voltage gap of 0.02 V, much smaller than 0.25 V for VOH and 0.27 V for MgVOH. CuVOH shows an enhanced exchange current density of 0.23 A g −1 , compared to 0.20 Amore »g −1 for VOH and 0.19 A g −1 for MgVOH. CuVOH delivers a zinc ion storage capacity of 379 mA h g −1 , higher than 349 mA h g −1 for MgVOH and 337 mA h g −1 for VOH at 0.5 A g −1 . CuVOH shows an energy efficiency of 72%, superior to 53% for VOH and 55% for MgVOH. All of the results suggest that pre-inserted Cu( ii ) cations played a critical role in catalyzing the zinc ion intercalation reaction, while the Mg( ii ) cations did not exert a detectable catalytic effect.« less