RESUMO
Lithium-sulfur (Li-S) batteries are widely regarded as one of the most promising next-generation high-energy-density energy storage devices. However, soluble lithium polysulfides (LiPSs) corrode Li metal and deteriorate the cycling stability of Li-S batteries. Understanding the reaction mechanism between LiPSs and Li metal anode is imperative. Herein, the reaction rate and products of LiPSs with Li metal anode, the composition and structure of the as-generated solid electrolyte interphase (SEI), and the mechanism of lithium nitrate (LiNO3) additives for inhibiting the corrosion reactions are systematically unveiled. Concretely, LiPSs react with Li metal anode more rapidly than Li salt and generate a Li2S-rich SEI. The Li2S-rich SEI is highly reactive with LiPSs, which exacerbates the formation of dendritic Li and the continuous corrosion of active Li. LiNO3 functions dominantly by modulating the solvation structure of LiPSs and inherently reducing the reactivity of LiPSs, rather than the conventional understanding of LiNO3 participating in the formation of SEI. This work reveals the reaction mechanism between LiPSs and Li metal anode and inspires rational regulating of the solvation structure of LiPSs for stabilizing Li metal anode in Li-S batteries.
RESUMO
The cycle life of high-energy-density lithium-sulfur (Li-S) batteries is severely plagued by the incessant parasitic reactions between Li metal anodes and reactive Li polysulfides (LiPSs). Encapsulating Li-polysulfide electrolyte (EPSE) emerges as an effective electrolyte design to mitigate the parasitic reactions kinetically. Nevertheless, the rate performance of Li-S batteries with EPSE is synchronously suppressed. Herein, the sacrifice in rate performance by EPSE is circumvented while mitigating parasitic reactions by employing hexyl methyl ether (HME) as a co-solvent. The specific capacity of Li-S batteries with HME-based EPSE is nearly not decreased at 0.1â C compared with conventional ether electrolytes. With an ultrathin Li metal anode (50â µm) and a high-areal-loading sulfur cathode (4.4â mgS cm-2 ), a longer cycle life of 113â cycles was achieved in HME-based EPSE compared with that of 65â cycles in conventional ether electrolytes at 0.1â C. Furthermore, both high energy density of 387â Wh kg-1 and stable cycle life of 27â cycles were achieved in a Li-S pouch cell (2.7â Ah). This work inspires the feasibility of regulating the solvation structure of LiPSs in EPSE for Li-S batteries with balanced performance.
RESUMO
Vascular smooth muscle cells (SMCs) are circumferentially oriented perpendicular to the blood vessel and maintain the contractile phenotype in physiological conditions. They can sense the mechanical forces of blood vessels expanding and contracting and convert them into biochemical signals to regulate vascular homeostasis. However, the real-time monitoring of mechanically evoked biochemical response while maintaining SMC oriented growth remains an important challenge. Herein, we developed a stretchable electrochemical sensor by electrospinning aligned and elastic polyurethane (PU) nanofibers on the surface of PDMS film and further modification of conductive polymer PEDOT:PSS-LiTFSI-CoPc (PPLC) on the nanofibers (denoted as PPLC/PU/PDMS). The aligned nanofibers on the electrode surface could guide the oriented growth of SMCs and maintain the contractile phenotype, and the modification of PPLC endowed the electrode with good electrochemical sensing performance and stability under mechanical deformation. By culturing cells on the electrode surface, the oriented growth of SMCs and real-time monitoring of stretch-induced H2O2 release were achieved. On this basis, the changes of H2O2 level released by SMCs under the pathology (hypertension) and intervention of natural product resveratrol were quantitatively monitored, which will be helpful to further understand the occurrence and development of vascular-related diseases and the mechanisms of pharmaceutical intervention.
Assuntos
Nanofibras , Peróxido de Hidrogênio , Mecanotransdução Celular , Miócitos de Músculo Liso , Poliuretanos , EletrodosRESUMO
Practical lithium-sulfur (Li-S) batteries are severely plagued by the instability of solid electrolyte interphase (SEI) formed in routine ether electrolytes. Herein, an electrolyte with 1,3,5-trioxane (TO) and 1,2-dimethoxyethane (DME) as co-solvents is proposed to construct a high-mechanical-stability SEI by enriching organic components in Li-S batteries. The high-mechanical-stability SEI works compatibly in Li-S batteries. TO with high polymerization capability can preferentially decompose and form organic-rich SEI, strengthening mechanical stability of SEI, which mitigates crack and regeneration of SEI and reduces the consumption rate of active Li, Li polysulfides, and electrolytes. Meanwhile, DME ensures high specific capacity of S cathodes. Accordingly, the lifespan of Li-S batteries increases from 75â cycles in routine ether electrolyte to 216â cycles in TO-based electrolyte. Furthermore, a 417â Wh kg-1 Li-S pouch cell undergoes 20â cycles. This work provides an emerging electrolyte design for practical Li-S batteries.
RESUMO
Lithium-sulfur (Li-S) batteries are regarded as promising high-energy-density energy storage devices. However, the cycling stability of Li-S batteries is restricted by the parasitic reactions between Li metal anodes and soluble lithium polysulfides (LiPSs). Encapsulating LiPS electrolyte (EPSE) can efficiently suppress the parasitic reactions but inevitably sacrifices the cathode sulfur redox kinetics. To address the above dilemma, a redox comediation strategy for EPSE is proposed to realize high-energy-density and long-cycling Li-S batteries. Concretely, dimethyl diselenide (DMDSe) is employed as an efficient redox comediator to facilitate the sulfur redox kinetics in Li-S batteries with EPSE. DMDSe enhances the liquid-liquid and liquid-solid conversion kinetics of LiPS in EPSE while maintains the ability to alleviate the anode parasitic reactions from LiPSs. Consequently, a Li-S pouch cell with a high energy density of 359â Wh kg-1 at cell level and stable 37â cycles is realized. This work provides an effective redox comediation strategy for EPSE to simultaneously achieve high energy density and long cycling stability in Li-S batteries and inspires rational integration of multi-strategies for practical working batteries.
RESUMO
Long cycling lifespan is a prerequisite for practical lithium-sulfur batteries yet is restricted by side reactions between soluble polysulfides and the lithium-metal anode. The regulation on solvation structure of polysulfides renders encapsulating polysulfides electrolytes (EPSE) as a promising solution to suppress the parasitic reactions. The solvating power of the solvents in the outer solvent shell of lithium polysulfides is critical for the encapsulation effect of EPSE. Herein, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) is demonstrated as a superior outer-shell solvent to construct EPSE. Based on the large steric hindrance of the fluorohydrocarbon chains, the electron-withdrawing perfluoro segment (CF2  further endows HFE with prominently weak solvating power. The HFE-EPSE improves the lifespan from 54 to 135 cycles for lithium-sulfur batteries with an ultrathin lithium-metal anode (50 µm) and high-areal-loading sulfur cathode (4.4 mg cm-2 ). Furthermore, a 334 Wh kg-1 lithium-sulfur pouch cell (2.4 Ah level) with HFE-EPSE stably undergoes 25 cycles. This work demonstrates the role of weakening solvating power of outer-shell solvents to construct superior EPSE and inspires the significance of the solvation chemistry of polysulfides to achieve practical lithium-sulfur batteries.
RESUMO
Many cells in vivo have their inherent motions, which involve numerous biochemical and biophysical signals synergistically regulating cell behavior and function. However, existing methods offer little information about the concurrently chemical and physical responses of dynamically pulsing cells. Here, we report a soft electrode with an electrospun poly(3,4-ethylenedioxythiophene) (PEDOT)-based nanomesh to fully comply with spontaneous motions of cells. Moreover, this electrode demonstrated excellent electrical conductivity, electrochemical performance and cellular biocompatibility. Cardiomyocytes cultured thereon exhibited autonomous and rhythmic contractility, and synchronously induced mechanical deformation of the underlying electrode, which allowed real-time monitoring of nitric oxide release and electrophysiological activity of cardiomyocytes. This work provides a promising way toward recording chemical and electrical signals of biological systems with their natural motions.
Assuntos
Miócitos Cardíacos , Polímeros , Condutividade Elétrica , Eletrodos , Fenômenos EletrofisiológicosRESUMO
Lithium-sulfur (Li-S) battery is identified as one of the most promising next-generation energy storage systems due to its ultra-high theoretical energy density up to 2600 Wh kg-1 . However, Li metal anode suffers from dramatic volume change during cycling, continuous corrosion by polysulfide electrolyte, and dendrite formation, rendering limited cycling lifespan. Considering Li metal anode as a double-edged sword that contributes to ultrahigh energy density as well as limited cycling lifespan, it is necessary to evaluate Li-based alloy as anode materials to substitute Li metal for high-performance Li-S batteries. In this contribution, the authors systematically evaluate the potential and feasibility of using Li metal or Li-based alloys to construct Li-S batteries with an actual energy density of 500 Wh kg-1 . A quantitative analysis method is proposed by evaluating the required amount of electrolyte for a targeted energy density. Based on a three-level (ideal material level, practical electrode level, and pouch cell level) analysis, highly lithiated lithium-magnesium (Li-Mg) alloy is capable to achieve 500 Wh kg-1 Li-S batteries besides Li metal. Accordingly, research on Li-Mg and other Li-based alloys are reviewed to inspire a promising pathway to realize high-energy-density and long-cycling Li-S batteries.