Interfacial Chemistry in Solid-State Batteries: Formation of Interphase and Its Consequences

Benefiting from extremely high shear modulus and high ionic transference number, solid electrolytes are promising candidates to address both the dendrite-growth and electrolyte-consumption problems inherent to the widely adopted liquid-phase electrolyte batteries. However, solid electrolyte/electrode interfaces present high resistance and complicated morphology, hampering the development of solid-state battery systems, while requiring advanced analysis for rational improvement. Here, we employ an ultrasensitive three-dimensional (3D) chemical analysis to uncover the dynamic formation of interphases at the solid electrolyte/electrode interface. While the formation of interphases widens the electrochemical window, their electronic and ionic conductivities determine the electrochemical performance and have a large influence on dendrite growth. Our results suggest that, contrary to the general understanding, highly stable solid electrolytes with metal anodes in fact promote fast dendritic formation, as a result of less Li consumption and much larger curvature of dendrite tips that leads to an enhanced electric driving force. Detailed thermodynamic analysis shows an interphase with low electronic conductivity, high ionic conductivity, and chemical stability, yet having a dynamic thickness and uniform coverage is needed to prevent dendrite growth. This work provides a paradigm for interphase design to address the dendrite challenge, paving the way for the development of robust, fully operational solid-state batteries

Y‑Doped NASICON-type LiZr₂(PO₄)₃ Solid Electrolytes for Lithium-Metal Batteries

Low ionic conductivity limits the development of NASICON-type LiZr₂(PO₄)₃ (LZP) for solid-state batteries. Here, we present the possible factors that may affect the conductivity and further establish the relationships among conductivity, crystal structure, relative density, grain size, chemical composition, and elemental distribution. The conditions for the existence of the four phases of LZP (α, α′, β, and β′) and the phase transition processes among them are systematically clarified. With secondary ion mass spectrometry, the spatial distribution of elements within the grains and grain boundaries is clearly presented. On the basis of our results, proper elemental doping, high sintering temperature, and especially fast cool down rate are all indispensable to stabilize the high-conductivity (α) phase at room temperature. Finally, we demonstrate the feasibility of lithium-based batteries with this LZP solid electrolyte and commercial cathodes. This work provides insights for preparing LZP with high conductivity and paves the way for the development of solid-state batteries

Interfacial Chemistry in Solid-State Batteries: Formation of Interphase and Its Consequences

Benefiting from extremely high shear modulus and high ionic transference number, solid electrolytes are promising candidates to address both the dendrite-growth and electrolyte-consumption problems inherent to the widely adopted liquid-phase electrolyte batteries. However, solid electrolyte/electrode interfaces present high resistance and complicated morphology, hampering the development of solid-state battery systems, while requiring advanced analysis for rational improvement. Here, we employ an ultrasensitive three-dimensional (3D) chemical analysis to uncover the dynamic formation of interphases at the solid electrolyte/electrode interface. While the formation of interphases widens the electrochemical window, their electronic and ionic conductivities determine the electrochemical performance and have a large influence on dendrite growth. Our results suggest that, contrary to the general understanding, highly stable solid electrolytes with metal anodes in fact promote fast dendritic formation, as a result of less Li consumption and much larger curvature of dendrite tips that leads to an enhanced electric driving force. Detailed thermodynamic analysis shows an interphase with low electronic conductivity, high ionic conductivity, and chemical stability, yet having a dynamic thickness and uniform coverage is needed to prevent dendrite growth. This work provides a paradigm for interphase design to address the dendrite challenge, paving the way for the development of robust, fully operational solid-state batteries

Durability of the Li_1+<i>x</i>Ti_2–<i>x</i>Al_<i>x</i>(PO₄)₃ Solid Electrolyte in Lithium–Sulfur Batteries

Adoption of cells with a solid-state electrolyte is a promising solution for eliminating the polysulfide shuttle problem in Li–S batteries. Among the various known lithium-ion conducting solid electrolytes, the sodium superionic conductor (NASICON)-type Li_1+<i>x</i>Ti_2–<i>x</i>Al_<i>x</i>(PO₄)₃ offers the advantage of good stability under ambient conditions and in contact with air. Accordingly, we present here a comprehensive assessment of the durability of Li_1+<i>x</i>Ti_2–<i>x</i>Al_<i>x</i>(PO₄)₃ in contact with polysulfide solution and in Li–S cells. Because of its high reduction potential (2.5 V vs Li/Li⁺), Li_1+<i>x</i>Ti_2–<i>x</i>Al_<i>x</i>(PO₄)₃ gets lithiated in contact with lithium polysulfide solution and Li₂CO₃ is formed on the particle surface, blocking the interfacial lithium-ion transport between the liquid and solid-state electrolytes. After the lithium insertion into the NASICON framework, the crystal expands in an anisotropic way, weakening the crystal bonds, causing fissures and resultant cracks in the ceramic, corroding the grain boundaries by polysulfide solution, and leaving unfavorable pores. The assembly of pores creates a gateway for polysulfide diffusion from the cathode side to the anode side, causing an abrupt decline in cell performance. Therefore, the solid-state electrolytes need to have good chemical compatibility with both the electrode and electrolyte, long-term stability under harsh chemical environment, and highly stable grain boundaries

Polyester with Pendent Acetylcholine-Mimicking Functionalities Promotes Neurite Growth

Successful regeneration of nerves can benefit from biomaterials that provide a supportive biochemical and mechanical environment while also degrading with controlled inflammation and minimal scar formation. Herein, we report a neuroactive polymer functionalized by covalent attachment of the neurotransmitter acetylcholine (Ach). The polymer was readily synthesized in two steps from poly­(sebacoyl diglyceride) (PSeD), which previously demonstrated biocompatibility and biodegradation in vivo. Distinct from prior acetylcholine-biomimetic polymers, PSeD-Ach contains both quaternary ammonium and free acetyl moieties, closely resembling native acetylcholine structure. The polymer structure was confirmed via ¹H nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Hydrophilicity, charge, and thermal properties of PSeD-Ach were determined by tensiometer, zetasizer, differential scanning calorimetry, and thermal gravimetric analysis, respectively. PC12 cells exhibited the greatest proliferation and neurite outgrowth on PSeD-Ach and laminin substrates, with no significant difference between these groups. PSeD-Ach yielded much longer neurite outgrowth than the control polymer containing ammonium but no the acetyl group, confirming the importance of the entire acetylcholine-like moiety. Furthermore, PSeD-Ach supports adhesion of primary rat dorsal root ganglions and subsequent neurite sprouting and extension. The sprouting rate is comparable to the best conditions from previous report. Our findings are significant in that they were obtained with acetylcholine-like functionalities in 100% repeating units, a condition shown to yield significant toxicity in prior publications. Moreover, PSeD-Ach exhibited favorable mechanical and degradation properties for nerve tissue engineering application. Humidified PSeD-Ach had an elastic modulus of 76.9 kPa, close to native neural tissue, and could well recover from cyclic dynamic compression. PSeD-Ach showed a gradual in vitro degradation under physiologic conditions with a mass loss of 60% within 4 weeks. Overall, this simple and versatile synthesis provides a useful tool to produce biomaterials for creating the appropriate stimulatory environment for nerve regeneration

Understanding the Redox Obstacles in High Sulfur-Loading Li–S Batteries and Design of an Advanced Gel Cathode

Lithium–sulfur batteries with a high energy density are being considered a promising candidate for next-generation energy storage. However, realization of Li–S batteries is plagued by poor sulfur utilization due to the shuttle of intermediate lithiation products between electrodes and its dynamic redistribution. To optimize the sulfur utilization, an understanding of its redox behavior is essential. Herein, we report a gel cathode consisting of a polysulfide-impregnated O- and N-doped porous carbon and an independent, continuous, and highly conducting 3-dimensional graphite film as the charge-transfer network. This design decouples the function of electron conduction and polysulfide absorption, which is beneficial for understanding the sulfur redox behavior and identifying the dominant factors leading to cell failure when the cells have high sulfur content and insufficient electrolyte. This design also opens up new prospects of tuning the properties of Li–S batteries via separately designing the material functions of electron conduction and polysulfide absorption

Surface-Enhanced Raman Scattering Detection of Pesticide Residues Using Transparent Adhesive Tapes and Coated Silver Nanorods

The efficient extraction of analytes from complex and severe environments is significant for promoting the surface-enhanced Raman scattering (SERS) technique to actual applications. In this paper, a proof-of-concept strategy is proposed for the rapid detection of pesticide residues by utilizing the flexible, transparent, and adhesive properties of commercial tapes and SERS performance of Al₂O₃-coated silver nanorod (AgNR@Al₂O₃) arrays. The function of tapes is to rapidly transfer the analytes from the actual surface to the SERS substrate. The novel “tape-wrapped SERS (T-SERS)” approach was constructed by a simple “paste, peel off, and paste again” procedure. The easily obtained but clearly distinguished SERS signals allow us to quickly determine the constituents of complex surfaces, such as tetramethylthiuram disulfide and thiabendazole pesticides from fruits and vegetables, which may be practically applied to food safety, environmental monitoring, and industrial production process controlling

Plating a Dendrite-Free Lithium Anode with a Polymer/Ceramic/Polymer Sandwich Electrolyte

A cross-linked polymer containing pendant molecules attached to the polymer framework is shown to form flexible and low-cost membranes, to be a solid Li⁺ electrolyte up to 270 °C, much higher than those based on poly­(ethylene oxide), to be wetted by a metallic lithium anode, and to be not decomposed by the metallic anode if the anions of the salt are blocked by a ceramic electrolyte in a polymer/ceramic membrane/polymer sandwich electrolyte (PCPSE). In this sandwich architecture, the double-layer electric field at the Li/polymer interface is reduced due to the blocked salt anion transfer. The polymer layer adheres/wets the lithium metal surface and makes the Li-ion flux at the interface more homogeneous. This structure integrates the advantages of the ceramic and polymer. With the PCPSE, all-solid-state Li/LiFePO₄ cells showed a notably high Coulombic efficiency of 99.8–100% over 640 cycles

Temperature-Immune, Wide-Range Flexible Robust Pressure Sensors for Harsh Environments

Flexible pressure sensors possess vast potential for various applications such as new energy batteries, aerospace engines, and rescue robots owing to their exceptional flexibility and adaptability. However, the existing sensors face significant challenges in maintaining long-term reliability and environmental resilience when operating in harsh environments with variable temperatures and high pressures (∼MPa), mainly due to possible mechanical mismatch and structural instability. Here, we propose a composite scheme for a flexible piezoresistive pressure sensor to improve its robustness by utilizing material design of near-zero temperature coefficient of resistance (TCR), radial gradient pressure-dividing microstructure, and flexible interface bonding process. The sensing layer comprising multiwalled carbon nanotubes (MWCNTs), graphite (GP), and thermoplastic polyurethane (TPU) was optimized to achieve a near-zero temperature coefficient of resistance over a temperature range of 25–70 °C, while the radial gradient microstructure layout based on pressure division increases the range of pressure up to 2 MPa. Furthermore, a flexible interface bonding process introduces a self-soluble transition layer by direct-writing TPU bonding solution at the bonding interface, which enables the sensor to achieve signal fluctuations as low as 0.6% and a high interface strength of up to 1200 kPa. Moreover, it has been further validated for its capability of monitoring the physiological signals of athletes as well as the long-term reliable environmental resilience of the expansion pressure of the power cell. This work demonstrates that the proposed scheme sheds new light on the design of robust pressure sensors for harsh environments

Inhibition of autophagy protects against PAMAM dendrimers-induced hepatotoxicity

<p>Toxicity of nanomaterials is one of the biggest challenges in their medicinal applications. Although toxicities of nanomaterials have been widely reported, the exact mechanisms of toxicities are still not well elucidated. Consequently, the exploration of approaches to attenuate toxicities of nanomaterials is limited. In this study, we reported that poly-amidoamine (PAMAM) dendrimers, a widely used nanomaterial in the pharmaceutical industry, caused toxicity of human liver cells by inducing cell growth inhibition, mitochondria damage, and apoptosis. Meanwhile, autophagy was activated in PAMAM dendrimers-induced toxicity and inhibition of autophagy-rescued viability of hepatic cells, indicating that autophagy played a key role in PAMAM dendriemrs-induced hepatotoxicity. To further explore approaches to attenuate PAMAM dendrimers-induced liver injury, effects of autophagic inhibitors on PAMAM dendrimers’ hepatotoxicity were investigated in an <i>in vivo</i> model. Autophagy blockage in PAMAM dendrimers-administered mice led to weight restoration, damage reversion of liver tissue, and protection against changes of serum biochemistry parameters. Moreover, inhibition of Akt/mTOR and activation of Erk1/2 signaling pathways were involved in PAMAM dendrimers-induced autophagy. Collectively, these findings indicated that autophagy was associated with PAMAM dendrimers-induced hepatotoxicity, and supported the possibility that autophagy inhibitors could be used to reduce hepatotoxicity of PAMAM dendrimers.</p