Intrinsic Lithiophilicity of Li–Garnet Electrolytes Enabling High‐Rate Lithium Cycling

Solid‐state lithium batteries are widely considered as next‐generation lithium‐ion battery technology due to the potential advantages in safety and performance. Among the various solid electrolyte materials, Li–garnet electrolytes are promising due to their high ionic conductivity and good chemical and electrochemical stabilities. However, the high electrode/electrolyte interfacial impedance is one of the major challenges. Moreover, short circuiting caused by lithium dendrite formation is reported when using Li–garnet electrolytes. Here, it is demonstrated that Li–garnet electrolytes wet well with lithium metal by removing the intrinsic impurity layer on the surface of the lithium metal. The Li/garnet interfacial impedance is determined to be 6.95 Ω cm2 at room temperature. Lithium symmetric cells based on the Li–garnet electrolytes are cycled at room temperature for 950 h and current density as high as 13.3 mA cm−2 without showing signs of short circuiting. Experimental and computational results reveal that it is the surface oxide layer on the lithium metal together with the garnet surface that majorly determines the Li/garnet interfacial property. These findings suggest that removing the superficial impurity layer on the lithium metal can enhance the wettability, which may impact the manufacturing process of future high energy density garnet‐based solid‐state lithium batteries.By removing the impurity layer on the surface of the lithium metal, Li–garnet electrolytes are demonstrated to well wet the lithium metal, rendering a Li/garnet interfacial impedance of 6.95 Ω cm2, stable galvanostatic cycling for 950 h, and a current density as high as 13.3 mA cm−2 without showing any sign of short circuiting at room temperature.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154451/1/adfm201906189-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154451/2/adfm201906189.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154451/3/adfm201906189_am.pd

Synthesis, Integration, and Characterization of Functional Inorganic Nanomaterials

In the past decade nanomaterials have attracted the interest of scientists and engineers all over the world due to their unique properties. Through their devoted experimental efforts, limited advances have been made on the synthesis of nanomaterials, the integration of nanomaterials into the structures of larger scales, and the property study of nanomaterials to explore possible applications. Despite the huge amount of money, resources, and effort invested in nanomaterials, several challenges still remain as obstacles on the way towards the successful large scale use of nanomaterials to benefit human life and society. For example, the need for low-cost, robust, and highly productive manufacturing methods and the demand for efficient integration of nanomaterials with materials and devices of larger length scales are still left unmet. The objective of this work was to utilize cost-efficient nanofabrication methods such as template-assisted fabrication, electrodeposition, and chemical vapor deposition to fabricate nanomaterials, integrate nanomaterials with larger structures to form a hierarchical composite, and explore the application of unique nanostructured electrode in lithium-ion batteries. Thus the thesis consists of three main parts: (1) fabrication of one-dimensional inorganic nanomaterials such as metal nanowires, metal nanorods, and carbon nanotubes with good control over shape and dimension; (2) synthesis of hierarchical carbon nanofibers on carbon microfibers and/or glass microfibers; and (3) development of nanostructured anodes to improve high-rate capability of lithium-ion batteries by adapting nanorod arrays as miniature current collectors

Palladium-catalyzed regioselective C-S bond cleavage of thiophenes.

International audienceHerein, a Pd-catalyzed reaction of simple and diverse bromothiophenes with alkynes via regioselective C-S bond activation is reported. This provides a new approach to prepare sulfur-based heterocycles and fulvenes

Recent progress of multilayer polymer electrolytes for lithium batteries

The significant market for electric vehicles and portable electronic devices is driving the development of high-energy-density solid-state lithium batteries. However, the solid electrolyte is still the main obstacle to the development of solid-state lithium batteries, mainly due to the lack of a single solid electrolyte that is compatible with both high-voltage cathodes and lithium metal anodes. These problems can potentially be solved with multilayer electrolytes. The property of each layer of the electrolyte can be tuned separately, which not only meets the different needs of the cathode and anode but also makes up for the shortcomings of each layer of the electrolyte, thereby achieving good mechanical properties and chemical and electrochemical stability. This review first presents a brief introduction to homogeneous single-layer electrolytes. The design principles of multilayer polymer electrolytes and the application of these principles using examples from recent work are then introduced. Finally, several suggestions as guides for future work are given

Catalytic C–H and C–S Bond Activation of Thiophenes

A new Pd-catalyzed reaction of thiophenes with alkynes via C–H and C–S bond activation has been developed. This provides a new approach to prepare sulfur-containing compounds. An interesting salt effect was observed, and the reaction’s efficiency and selectivity depend not only on the type but also on the amount of the salt used

Synthesis of Orthorhombic Perovskite-Type ZnSnO₃ Single-Crystal Nanoplates and Their Application in Energy Harvesting

In recent years, lead-free piezoelectric nanogenerators have attracted much attention because of their great potential for harvesting energy from the environment. Here, we report the first synthesis of two-dimensional (2D) single-crystal ZnSnO₃ hexagon nanoplates and the fabrication of ZnSnO₃ nanoplate-based nanogenerators. The orthorhombic perovskite-structured ZnSnO₃ nanoplates with (111) facets of the exposed plate surface are successfully synthesized via a one-step hydrothermal reaction. Piezoelectric nanogenerators are then fabricated using the as-synthesized single-crystal ZnSnO₃ nanoplates and poly­(dimethylsiloxane) (PDMS). A <i>d</i>₃₃ value as high as 49 pC/N for the ZnSnO₃@PDMS composite was obtained without any electrical poling process, which demonstrates that the single-crystal ZnSnO₃ nanoplates have a single-domain structure. To the best of our knowledge, this <i>d</i>₃₃ value is also the highest among lead-free piezoelectric composites. A bending strain can induce the piezoelectric nanogenerator (PENG) to generate a large, stable, and sustainable output open circuit voltage of 20 V and a short circuit current of 0.6 μA, which are higher than many other PENGs. The output signals are sufficient to light a single light-emitting diode (LED), which shows the great potential of the material for scavenging mechanical energy from moving entities, such as road vehicles, railway vehicles, and humans

Synthesis of Orthorhombic Perovskite-Type ZnSnO₃ Single-Crystal Nanoplates and Their Application in Energy Harvesting

In recent years, lead-free piezoelectric nanogenerators have attracted much attention because of their great potential for harvesting energy from the environment. Here, we report the first synthesis of two-dimensional (2D) single-crystal ZnSnO₃ hexagon nanoplates and the fabrication of ZnSnO₃ nanoplate-based nanogenerators. The orthorhombic perovskite-structured ZnSnO₃ nanoplates with (111) facets of the exposed plate surface are successfully synthesized via a one-step hydrothermal reaction. Piezoelectric nanogenerators are then fabricated using the as-synthesized single-crystal ZnSnO₃ nanoplates and poly­(dimethylsiloxane) (PDMS). A <i>d</i>₃₃ value as high as 49 pC/N for the ZnSnO₃@PDMS composite was obtained without any electrical poling process, which demonstrates that the single-crystal ZnSnO₃ nanoplates have a single-domain structure. To the best of our knowledge, this <i>d</i>₃₃ value is also the highest among lead-free piezoelectric composites. A bending strain can induce the piezoelectric nanogenerator (PENG) to generate a large, stable, and sustainable output open circuit voltage of 20 V and a short circuit current of 0.6 μA, which are higher than many other PENGs. The output signals are sufficient to light a single light-emitting diode (LED), which shows the great potential of the material for scavenging mechanical energy from moving entities, such as road vehicles, railway vehicles, and humans

Sn-O Dual-Substituted Chlorine-Rich Argyrodite Electrolyte with Enhanced Moisture and Electrochemical Stability

Chlorine-rich argyrodite sulfides are one of the most promising solid electrolytes for all-solid-state batteries owing to their remarkable ionic conductivity and decent mechanical properties. However, their application has been limited by imperfections such as moisture instability and poor electrochemical stability. Herein, a Sn and O is proposed dual-substitution strategy in Li5.4PS4.4Cl1.6 (LPSC) to improve the moisture tolerance and boost the electrochemical performance. The optimized composition of Li5.5(P0.9Sn0.1)(S4.2O0.2)Cl1.6 (LPSC-10) sintered at 500 °C exhibits a room-temperature ionic conductivity of 8.7 mS cm−1, an electrochemical window up to 5 V, a critical current density of 1.2 mA cm−2, and stable lithium plating/striping. When exposed to humid air, LPSC-10 exhibits a small increment in total resistance, generates a mild amount of H2S gas, and displays favorable structure stability after heat treatment. The first-principles calculation confirms that the dual-substituted composition less tends to be hydrolyzed than the un-substituted one. The all-solid-state battery with LiIn|NMC811 electrodes presents a high initial discharge capacity of 103.6 mAh g−1 at 0.5 C rates and maintains 101.4 mAh g−1 at the 100th cycle, with a 97.9% capacity retention rate. The present study opens a new alternative for simultaneously promoting moisture and electrochemical stability.By introducing Sn and O dual substitution in chlorine-rich argyrodite Li5.4PS4.4Cl1.6, and comparing the different substitution levels, Li5.5(P0.9Sn0.1)(S4.2O0.2)Cl1.6 is demonstrated to possess the enhanced moisture stability, exhibit the dendrite-free lithium stripping/plating at 0.5 mA cm−2, and enable high capacity retention of 97.9% at 0.5 C rate (101.4 mAh g−1 at 100th cycle) using NMC cathode.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/176105/1/adfm202211805.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/176105/2/adfm202211805_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/176105/3/adfm202211805-sup-0001-SuppMat.pd

Origin of Lithiophilicity of Lithium Garnets: Compositing or Cleaning?

Garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZTO), a promising solid-state electrolyte, is reported to exhibit lithiophobicity. Herein, it is demonstrated that the origin of the lithiophobicity is closely related to the surface compositions of both the lithium and LLZTO. Surface impurities with high melting points such as Li2O, Li2CO3, LiOH, or LiF inhibit the wettability between lithium metal and LLZTO, and the widely adopted compositing strategy may improve the wettability by merely breaking the surface impurity layers. A simple but effective “polishing-and-spreading” strategy is proposed to remove the surface impurities and obtain clean Li/LLZTO interfaces. Thus, a tight and continuous Li/LLZTO interface with an interfacial resistance of 17.5 Ω cm2 is achieved, which leads to stable cycling of the symmetric Li cells and a critical current density up to 2.8 mA cm–2. This work provides a new perspective to understand the lithiophilicity of garnet-type electrolytes and contributes to designing robust Li/garnet interfaces.By comparing the wetting effect of different Li-based composite anodes, and using a “polishing-and-spreading” strategy, lithium garnet is demonstrated to well wet Li, rendering a Li/LLZO interfacial impedance of 17.5 Ω cm2 and a critical current density of 2.8 mA cm–2, without using any intermediate layer or compositing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/175061/1/adfm202205778.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/175061/2/adfm202205778-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/175061/3/adfm202205778_am.pd