A multifunctional graphene oxide-Zn(II)-triazole complex for improved performance of lithium-sulfur battery at low temperature

In-situ synthesis Fe3C@C/rGO as matrix for high performance lithium-sulfur batteries at room and low temperatures

People have been focusing on how to improve the specific capacity and cycling stability of lithium-sulfur batteries at room temperature, however, on some special occasions such as cold cities and aerospace fields, the operating temperature is low, which dramatically hinders the performance of batteries. Here, we report an iron carbide (Fe3C)/rGO composite as electrode host, the Fe3C nanoparticles in the composite have strong adsorption and high catalytic ability for polysulfide. The rGO makes the distribution of Fe3C nanoparticles more disperse, and this specific structure makes the deposition of Li2S more uniform. Therefore, it realizes the rapid transformation and high performance of lithium-sulfur batteries at both room and low temperatures. At room temperature, after 100 cycles at 1C current density, the reversible specific capacity of the battery can be stabilized at 889 ± 7.1 mAh/g. Even at -40 °C, in the first cycle battery still emits 542.9 ± 3.7 mAh/g specific capacity. This broadens the operating temperature for lithium-sulfur batteries and also provides a new idea for the selection of host materials for sulfur in low-temperature lithium-sulfur batteries.

Accelerating the Rate-Determining Steps of Sulfur Conversion Reaction for Lithium-Sulfur Batteries Working at an Ultrawide Temperature Range

Wide operation temperature is the crucial objective for an energy storage system that can be applied under harsh environmental conditions. For lithium-sulfur batteries, the "shuttle effect" of polysulfide intermediates will aggravate with the temperature increasing, while the reaction kinetics decreases sharply as the temperature decreasing. In particular, sulfur reaction mechanism at low temperatures seems to be quite different from that at room temperature. Here, through in situ Raman and electrochemical impedance spectroscopy studies, the newly emerged platform at cryogenic temperature corresponds to the reduction process of Li2S8 to Li2S4, which will be another rate-determining step of sulfur conversion reaction, in addition to the solid-phase conversion process of Li2S4 to Li2S2/Li2S at low temperatures. Porous bismuth vanadate (BiVO4) spheres are designed as sulfur host material, which achieve the rapid snap-transfer-catalytic process by shortening lithium-ion transport pathway and accelerating the targeted rate-determining steps. Such promoting effect greatly inhibits severe "shuttle effect" at high temperatures and simultaneously improves sulfur conversion efficiency in the cryogenic environment. The cell with the porous BiVO4 spheres as the host exhibits excellent rate capability and cycle performance under wide working temperatures.

Challenges and Solutions for Low-Temperature Lithium-Sulfur Batteries: A Review

The lithium-sulfur (Li-S) battery is considered to be one of the attractive candidates for breaking the limit of specific energy of lithium-ion batteries and has the potential to conquer the related energy storage market due to its advantages of low-cost, high-energy density, high theoretical specific energy, and environmental friendliness issues. However, the substantial decrease in the performance of Li-S batteries at low temperatures has presented a major barrier to extensive application. To this end, we have introduced the underlying mechanism of Li-S batteries in detail, and further concentrated on the challenges and progress of Li-S batteries working at low temperatures in this review. Additionally, the strategies to improve the low-temperature performance of Li-S batteries have also been summarized from the four perspectives, such as electrolyte, cathode, anode, and diaphragm. This review will provide a critical insight into enhancing the feasibility of Li-S batteries in low-temperature environments and facilitating their commercialization.

Medium-Entropy-Alloy FeCoNi Enables Lithium-Sulfur Batteries with Superb Low-Temperature Performance

Lithium-sulfur battery suffers from sluggish kinetics at low temperatures, resulting in serious polarization and reduced capacity. Here, this work introduces medium-entropy-alloy FeCoNi as catalysts and carbon nanofibers (CNFs) as hosts. FeCoNi nanoparticles are in suit synthesized in cotton-derived CNFs. FeCoNi with atomic-level mixing of each element can effectively modulate lithium polysulfides (LiPSs), multiple components making them promising to catalyze more LiPSs species. The higher configurational entropy endows FeCoNi@CNFs with extraordinary electrochemical activity, corrosion resistance, and mechanical properties. The fractal structure of CNFs provides a large specific surface area, leaving room for volume expansion and Li₂ S accumulation, facilitating electrolyte wetting. The unique 3D conductive network structure can suppress the shuttle effect by physicochemical adsorption of LiPSs. This work systematically evaluates the performance of the obtained Li₂ S₆ /FeCoNi@CNFs electrode. The initial discharge capacity of Li₂ S₆ /FeCoNi@CNFs reaches 1670.8 mAh g^-1 at 0.1 C under -20 °C. After 100 cycles at 0.2 C, the capacity decreases from 1462.3 to 1250.1 mAh g^-1 . Notably, even under -40 °C at 0.1 C, the initial discharge capacity of Li₂ S₆ /FeCoNi@CNFs still reaches 1202.8 mAh g^-1 . After 100 cycles at 0.2 C, the capacity retention rate is 50%. This work has important implications for the development of low-temperature Li-S batteries.

Chemical Sulfide Tethering Improves Low-Temperature Li-S Battery Cycling

Demands for energy storage and delivery continue to rise worldwide, making it imperative that reliable performance is achievable in diverse climates. Lithium-sulfur (Li-S) batteries offer a promising alternative to lithium-ion batteries owing to their substantially higher specific capacity and energy density. However, improvements to Li-S systems are still needed in low-temperature environments where polysulfide clustering and solubility limitations prohibit complete charge/discharge cycles. We address these issues by introducing thiophosphate-functionalized metal-organic frameworks (MOFs), capable of tethering polysulfides, into the cathode architecture. Compared to cells with the parent MOFs, cells containing the functionalized MOFs exhibit greater capacity delivery and decreased polarization for a range of temperatures down to -10 °C. We conduct thorough electrochemical analyses to ascertain the origins of performance differences and report an altered Li-S redox mechanism enabled by the thiophosphate moiety. This investigation is the first low-temperature Li-S study using MOF additives and represents a promising direction in enabling energy storage in extreme environments.

Coordination-Driven Hierarchical Assembly of Hybrid Nanostructures Based on 2D Materials

2D materials have received tremendous scientific and engineering interests due to their remarkable properties and broad-ranging applications such as energy storage and conversion, catalysis, biomedicine, electronics, and so forth. To further enhance their performance and endow them with new functions, 2D materials are proposed to hybridize with other nanostructured building blocks, resulting in hybrid nanostructures with various morphologies and structures. The properties and functions of these hybrid nanostructures depend strongly on the interfacial interactions between 2D materials and other building blocks. Covalent and coordination bonds are two strong interactions that hold high potential in constructing these robust hybrid nanostructures based on 2D materials. However, most 2D materials are chemically inert, posing problems for the covalent assembly with other building blocks. There are usually coordination atoms in most of 2D materials and their derivatives, thus coordination interaction as a strong interfacial interaction has attracted much attention. In this review, recent progress on the coordination-driven hierarchical assembly based on 2D materials is summarized, focusing on the synthesis approaches, various architectures, and structure-property relationship. Furthermore, insights into the present challenges and future research directions are also presented.

A graphene oxide functionalized energetic coordination polymer possesses good thermostability, heat release and combustion catalytic performance for ammonium perchlorate

A new energetic coordination polymer (ECP) composite, namely GO-Cu(ii)-AmTZ, has been synthesized by 3-amino-1,2,4-triazole (AmTZ) and multifunctional graphene oxide (GO) coordination with Cu(ii) successively. The ECP composite was further characterized through SEM, EDS and XPS analysis as well as FTIR and Raman spectroscopy. It shows high thermostability, high decomposition heat release and insensitivity to mechanical stimuli. What's more, thermal analysis data for ammonium perchlorate (AP) have been obtained by mechanically mixing GO-Cu(ii)-AmTZ and AP. The low-temperature decomposition (LTD, 335.3 °C) and high-temperature decomposition (HTD, 441.3 °C) peaks of AP were reduced to an exothermic peak at 298.4 °C at a heating rate of 10 °C min-1. GO-Cu(ii)-AmTZ exhibits outstanding catalytic performance by decreasing the activation energy from 168.7 kJ mol-1 to 122.4 kJ mol-1, indicating its promising application as a combustion catalyst for improving the thermal-catalytic decomposition performance of energetic materials largely. In addition, thermal analysis techniques including thermogravimetry coupled with mass spectrometry (TG/MS) and thermogravimetry coupled with infrared spectrometry (TG/IR) were employed to determine the decomposition mechanisms.

Enhanced Adsorptions to Polysulfides on Graphene-Supported BN Nanosheets with Excellent Li-S Battery Performance in a Wide Temperature Range

For Li-S batteries, the catalysis for S redox reaction is indispensable. A lot of multifunctional sulfur electrode support materials with have been investigated widely. However, most of these studies were carried out at room temperature, and the interaction between different components in the matrix is not often paid enough attention. Here, we report a graphene supported BN nanosheet composite in which the synergistic effect between BN and graphene greatly enhanced the adsorption for polysulfides, thus leading to excellent performance in a wide temperature range. When used as a host material of sulfur, it can make the Li-S battery apply to a wide range of temperatures, from -40 to 70 °C, delivering a high utilization of sulfur, an excellent rate capability, and outstanding cycling life. The capacity can stabilized at 888 mAh g^-1 at 2 C after 300 cycles with a capacity attenuation of <0.04% per cycle at 70 °C, and the battery can deliver a capacity above 650 mAh g^-1 at -40 °C.