Rational design and scalable engineering of artificial interphases for lithium metal anodes

Lithium (Li) metal anodes have experienced a resurgence of research in recent years, which has been fueled by advances in electrolyte chemistry (both solid and liquid), interfacial engineering, and rational design of electrode architectures1. This has enabled Coulombic efficiency values to push above 99.5%, and cycle life to extend into relevant ranges for transportation applications2. However, while performance metrics are beginning to approach relevant values for consideration of their use in electric vehicles, several fundamental questions remain on how Li metal anodes dynamically evolve during cycling, especially at high current densities. Towards this goal, there is a continued need for new methods to understand the evolving morphology from nucleation, to growth, to irreversible capacity loss.In this talk, operando optical microscopy will be discussed as an enabling platform to study the coupled chemical, electrochemical, mechanical, and morphological evolution of Li metal during plating and stripping. By time synchronization of the morphological evolution of Li metal anodes with electrochemical signatures during cycling, significant insights can be obtained into the mechanistic origins of poor performance3-4. Both cross-sectional and plan-view perspectives on the electrode surface will be described, which allow for a full 3-dimensional understanding of nucleation and growth processes. Video imaging of Li metal propagation in both liquid and solid electrolytes will be presented, and the critical role of mechanical stress evolution in Li metal morphology will be described5-6. A focus will be on the formation of “dead Li”, which form as a result of electronic isolation of metallic Li from the electrode surface3. Finally, strategies to modify surface chemistry and electrode geometry will be described, providing design rules for interfacial engineering of optimized electrodes2.1) Wood, K. N.; Noked, M.; Dasgupta, N. P. Lithium Metal Anodes: Toward an Improved Understanding of Coupled Morphological, Electrochemical, and Mechanical Behavior. ACS Energy Lett. 2017, 2 (3), 664–672.2) Chen, K.-H.; Sanchez, A. J.; Kazyak, E.; Davis, A. L.; Dasgupta, N. P. Synergistic Effect of 3D Current Collectors and ALD Surface Modification for High Coulombic Efficiency Lithium Metal Anodes. Adv. Energy Mater. 2019, 9 (4), 1802534.3) Wood, K. N.; Kazyak, E.; Chadwick, A. F.; Chen, K.-H.; Zhang, J.-G.; Thornton, K.; Dasgupta, N. P. Dendrites and Pits: Untangling the Complex Behavior of Lithium Metal Anodes through Operando Video Microscopy. ACS Cent. Sci. 2016, 2 (11) 790-801.4) Chen, K.-H.; Wood, K. N.; Kazyak, E.; LePage, W. S.; Davis, A. L.; Sanchez, A. J.; Dasgupta, N. P. Dead Lithium: Mass Transport Effects on Voltage, Capacity, and Failure of Lithium Metal Anodes. J. Mater. Chem. A 2017, 5 (23), 11671–11681.5) LePage, W. S.; Chen, Y.; Kazyak, E.; Chen, K.-H.; Sanchez, A. J.; Poli, A.; Arruda, E. M.; Thouless, M. D.; Dasgupta, N. P. Lithium Mechanics: Roles of Strain Rate and Temperature and Implications for Lithium Metal Batteries. J. Electrochem. Soc. 2019, 166 (2), A89–A97.6) Gupta, A.; Kazyak, E.; Craig, N.; Christensen, J.; Dasgupta, N. P.; Sakamoto, J. Evaluating the Effects of Temperature and Pressure on Li/PEO-LiTFSI Interfacial Stability and Kinetics. J. Electrochem. Soc. 2018, 165 (11), A2801–A2806.

The investigation of new photosensitizers for Grätzel-type organic dye-sensitized solar cells (DSSCs) remains a topic of interest for researchers of alternative solar cell materials. Over the past 20 years, considerable and increasing research efforts have been devoted to the design and synthesis of new materials, based on “donor, π-conjugated bridge, acceptor” (D–π–A) organic dye photosensitizers. In this paper, the computational chemistry methods are outlined and the design of organic sensitizers (compounds, dyes) is discussed. With reference to recent literature reports, rational molecular design is demonstrated as an effective process to study structure–property relationships. Examples from established organic dye sensitizer structures, such as TA-St-CA, Carbz-PAHTDDT (S9), and metalloporphyrin (PZn-EDOT), are used as reference structures for an examination of this concept applied to generate systematically modified structural derivatives and hence new photosensitizers (i.e., dyes). Using computer-aided rational design (CARD), the in silico design of new chromophores targeted an improvement in spectral properties via the tuning of electronic structures by substitution of molecular fragments, as evaluated by the calculation of absorption profiles. This mini review provides important rational design strategies for engineering new organic light-absorbing compounds towards improved spectral absorption and related optoelectronic properties of chromophores for photovoltaic applications, including the dye-sensitized solar cell (DSSC).

In-situ growth of hierarchical N-doped CNTs/Ni Foam scaffold for dendrite-free lithium metal anode

Magnesium metal anodes have attracted widespread attention for their high volumetric capacity and natural abundance, but are precluded from practical applications by poor rate capability and limited lifespan due to sluggish ion‐transfer kinetics and uneven deposition behavior. Herein, for the first time a grain‐boundary‐rich triphasic artificial hybrid interphase, consisting of Sb metal, Mg3Sb2 alloy, and MgCl2, is designed on Mg anode surface by a facile solution treatment method, enabling high‐rate and long‐cycle Mg plating/stripping behavior. The triphasic artificial hybrid interphase affords high magnesiophilicity and ionic conductivity to reduce the energy barriers for Mg2+ desolvation and deposition. Meanwhile, the abundant grain boundaries redistribute Mg2+ flux at the electrode‐electrolyte interface and guide uniform Mg deposition. Accordingly, the as‐designed Mg metal anode achieves ultralong cycling life of 350 h at a high current density of 5 mA cm−2 and a large areal capacity of 5 mAh cm−2, outperforming previously reported Mg metal anodes with artificial interphases. Full cells with Mo6 cathode also show extraordinary stability over a long lifespan of 8000 cycles at a high rate of 5 C. The rational artificial interphase design and the understanding of composition‐structure‐function relationships shed deep insights into the development of fast‐charging and long‐cycling Mg metal batteries.

Lithium Metal Anodes: A Recipe for Protection

A New General Paradigm for Understanding and Preventing Li Metal Penetration through Solid Electrolytes

The practical application of a lithium (Li) metal anode is limited by the uncontrolled growth of Li dendrites during cycling. Here, we present a rationally designed trilayer protective coating for stabilizing the Li anode at high current densities. The protective coating is designed to consist of silver (Ag), lithium fluoride (LiF), and poly(ethylene oxide) (PEO), in which the Ag layer facilitates rapid Li+ transfer and uniform deposition, benefiting high current density operations. The LiF layer suppresses direct anode-electrolyte reactions while offering mechanical robustness to suppress the formation of dendrites. The PEO layer acts to enhance the protective coating's toughness, which prevents detachment of Ag during lithium plating and stripping. As a result, the Li//Li symmetric cell can stably cycle for 1200 h at a high current density of 20 mA cm-2. Additionally, the full cell of Li//LFP shows stable cycling for 1000 cycles at 1.09 mA cm-2 (2.50 mg cm-2) and 80 cycles at 5 mA cm-2 (11.50 mg cm-2). This study introduces a new technique for designing a solid electrolyte interphase (SEI) to the scientific community by successfully compositing alloyed, inorganic, and organic layers.

Strategies and opportunities for engineering antifungal peptides for therapeutic applications

BackgroundRamie degumming is often carried out at high temperatures; therefore, thermostable alkaline pectate lyase (PL) is beneficial for ramie degumming for industrial applications. Thermostable PLs are usually obtained by exploring new enzymes or reconstructing existing enzyme by rational design. Here, we improved the thermostability of an alkaline pectate lyase (PelN) from Paenibacillus sp. 0602 with rational design and structure-based engineering.ResultsFrom 26 mutants, two mutants of G241A and G241V showed a higher thermostability compared with the wild-type PL. The mutant K93I showed increasing specific activity at 45 °C. Subsequently, we obtained combinational mutations (K93I/G241A) and found that their thermostability and specific activity improved simultaneously. The K93I/G241A mutant showed a half-life time of 15.9 min longer at 60 °C and a melting temperature of 1.6 °C higher than those of the wild PL. The optimum temperature decreased remarkably from 67.5 °C to 60 °C, accompanied by a 57% decrease in Km compared with the Km value of the wild-type strain. Finally, we found that the intramolecular interaction in PelN was the source in the improvements of molecular properties by comparing the model structures. Rational design of PelN was performed by stabilizing the α-helices with high conservation and increasing the stability of the overall structure of the protein. Two engineering strategies were applied by decreasing the mutation energy calculated by Discovery Studio and predicting the free energy in the process of protein folding by the PoPMuSiC algorithm.ConclusionsThe results demonstrated that the K93I/G241A mutant was more suitable for industrial production than the wild-type enzyme. Furthermore, the two forementioned strategies could be extended to reveal engineering of other kinds of industrial enzymes.

Solid-state batteries have seen a dramatic increase in research in recent years because of their ability to address safety challenges associated with flammable liquid electrolytes, and the potential to enable Li metal anodes. However, all solid-state interfaces present unique challenges, including high interfacial impedances, accommodation of mechanical stresses due to solid-solid interfacial contact, and (electro)chemical instabilities that can evolve during dynamic cycling conditions1.To address these challenges, our group focuses on gaining new fundamental insights into the coupled phenomena occurring at interfaces, and applies this knowledge to rationally design interfacial composition and structure to address the root cause of performance limitations. In this talk, I will first present a multi-modal in situ/operando characterization approach to study Li metal-solid electrolyte interfaces during cycling2-4. Mechanistic insight will be provided into solid-electrolyte interphase (SEI) evolution, as well as nucleation and growth dynamics of the Li metal anode during cycling. In addition to these coupled morphological/chemical/electrochemical phenomena, the unique mechanical properties of Li metal will be discussed in the context of solid-state battery interfaces4-5.Equipped with this fundamental knowledge, I will describe the rational design of interlayers at the Li metal-SE interface using Atomic Layer Deposition (ALD). Examples will be presented in both bulk solid-state battery interfaces, and thin film electrolytes deposited by ALD3,6-7. Through this interdisciplinary approach of fundamental materials chemistry and applied engineering, strategies to address future interfacial challenges will be addressed, pointing towards rational design and manufacturing of optimized interfaces.1) K. B. Hatzell, X. C. Chen, C. L. Cobb, N. P. Dasgupta, M. B. Dixit, L. E. Marbella, M. T. McDowell, P. P. Mukherjee, A. Verma, V. Viswanathan, A. S. Westover, W. G. Zeier “Challenges in Lithium Metal Anodes for Solid State Batteries” ACS Energy Lett. 5, 922 (2020).2) Gupta, E. Kazyak, N. Craig, J. Christensen, N. P. Dasgupta, J. Sakamoto, “Evaluating the Effects of Temperature and Pressure on Li/PEO-LiTFSI Interfacial Stability and Kinetics” J. Electrochem. Soc. 165, A2801 (2018).3) A. L. Davis, R. Garcia-Mendez, K. N. Wood, E. Kazyak, K.-H. Chen, G. Teeter, J. Sakamoto, N. P. Dasgupta “Electro-Chemo-Mechanical Evolution of Sulfide Solid Electrolyte/Li Metal Interfaces: Operando Analysis and ALD Interlayer Effects” J. Mater. Chem. A 8, 6291 (2020).4) E. Kazyak, R. Garcia-Mendez, W. S LePage, A. Sharafi, A. L. Davis, A. J. Sanchez, K.-H. Chen, C. Haslam, J. Sakamoto, N. P. Dasgupta “Li Penetration in Ceramic Solid Electrolytes: Operando Microscopy Analysis of Morphology, Propagation, and Reversibility” Matter 2, 1 (2020).5) W. S. LePage, Y. Chen, E. Kazyak, K.-H. Chen, A. J. Sanchez, A. Poli, E. M. Arruda, M. D. Thouless, N. P. Dasgupta “Lithium Mechanics: Roles of Strain Rate and Temperature and Implications for Lithium Metal Batteries” J. Electrochem. Soc. 166, A89 (2019).6) E. Kazyak, K.-H. Chen, K. N. Wood, A. L. Davis, T. Thompson, A. J. Sanchez, X. Wang, C. Wang, J. Sakamoto, N. P. Dasgupta, “Atomic Layer Deposition of the Solid Electrolyte Garnet Li7La3Zr2O12” Chem. Mater. 29, 3785 (2017).7) E. Kazyak, K.-H. Chen, A. L. Davis, S. Yu, A. J. Sanchez, J. Lasso, A. R. Bielinski, J. Sakamoto, D. J. Siegel, N. P. Dasgupta, “Atomic Layer Deposition and First Principles Modeling of Glassy Li3BO3-Li2CO3 Electrolytes for Solid-State Li Metal Batteries” J. Mater. Chem. A 6, 19425 (2018).

The unique structural characteristics of one‐dimensional (1D) hollow nanostructures result in intriguing physicochemical properties and wide applications, especially for electrochemical energy storage applications. In this Minireview, we give an overview of recent developments in the rational design and engineering of various kinds of 1D hollow nanostructures with well‐designed architectures, structural/compositional complexity, controllable morphologies, and enhanced electrochemical properties for different kinds of electrochemical energy storage applications (i.e. lithium‐ion batteries, sodium‐ion batteries, lithium‐sulfur batteries, lithium‐selenium sulfur batteries, lithium metal anodes, metal‐air batteries, supercapacitors). We conclude with prospects on some critical challenges and possible future research directions in this field. It is anticipated that further innovative studies on the structural and compositional design of functional 1D nanostructured electrodes for energy storage applications will be stimulated.

The unique structural characteristics of one-dimensional (1D) hollow nanostructures result in intriguing physicochemical properties and wide applications, especially for electrochemical energy storage applications. In this Minireview, we give an overview of recent developments in the rational design and engineering of various kinds of 1D hollow nanostructures with well-designed architectures, structural/compositional complexity, controllable morphologies, and enhanced electrochemical properties for different kinds of electrochemical energy storage applications (i.e. lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, lithium-selenium sulfur batteries, lithium metal anodes, metal-air batteries, supercapacitors). We conclude with prospects on some critical challenges and possible future research directions in this field. It is anticipated that further innovative studies on the structural and compositional design of functional 1D nanostructured electrodes for energy storage applications will be stimulated.

Lithium metal is one of the most attractive anode materials for next-generation lithium batteries due to its high specific capacity and low electrochemical potential. However, the poor cycling performance and serious safety hazards, caused by the growth of dendritic and mossy lithium, has long hindered the application of lithium metal based batteries. Herein, we reported a rational design of free-standing Cu nanowire (CuNW) network to suppress the growth of dendritic lithium via accommodating the lithium metal in three-dimensional (3D) nanostructures. We demonstrated that as high as 7.5 mA h cm(-2) of lithium can be plated into the free-standing copper nanowire (CuNW) current collector without the growth of dendritic lithium. The lithium metal anode based on the CuNW exhibited high Coulombic efficiency (average 98.6% during 200 cycles) and outstanding rate performance owing to the suppression of lithium dendrite growth and high conductivity of CuNW network. Our results demonstrate that the rational nanostructural design of current collector could be a promising strategy to improve the performance of lithium metal anode enabling its application in next-generation lithium-metal based batteries.

Aqueous zinc‐ion batteries (AZIBs) have garnered significant attention due to their abundant zinc resources, intrinsic safety, and environmental friendliness, making them highly promising candidates for large‐scale and low‐cost energy storage applications. Zinc metal anodes, with high gravimetric/volumetric specific capacity, are an indispensable component of advanced AZIBs. However, critical challenges including the dendrite formation at the zinc/electrolyte interface and parasitic reactions such as corrosion and hydrogen evolution (HER) triggered by high activity water result in low Coulombic Efficiency (CE), which severely limits the practical deployment of AZIBs. To address these issues, the rational design and construction of a stable zinc anode‐electrolyte interface are crucial for achieving long‐term stability and superior electrochemical performance. In recent years, a wide range of strategies—such as interface engineering, alloying, and host design—are proposed and developed to address the intrinsic limitations of zinc anodes. This review provides a timely and comprehensive overview of these approaches, with particular emphasis on controlled zinc deposition and interfacial protection, discussed from the perspective of metallic zinc anodes. Furthermore, the fundamental principles underlying these strategies are systematically analyzed, aiming to provide mechanistic insights that can guide the rational design of next‐generation anode for AZIBs in large‐scale energy storage applications.

Silicious nanowires enabled dendrites suppression and flame retardancy for advanced lithium metal anodes