Lithium-selenium Batteries Research Articles

Metal Atom-Decorated Carbon Nanomaterials for Enhancing Li-S/Se Batteries Performances: A Mini Review

Lithium-sulfur (Li-S) and lithium-selenium (Li-Se) batteries are both facing the cathode issues of low Coulombic efficiency and unstable cycling stability due to the severe shuttle effect of lithium polysulfides or lithium polyselenides. Simultaneously inhibiting polysulfides/polyselenides dissolution in organic electrolytes and propelling them to conversion via introducing polar, catalytic materials has been proven as an effective strategy to enhance the durability of Li-S and Li-Se batteries. In this mini review, we systematically introduce various metal atom-decorated carbon nanomaterials to determine how to enhance the electrochemical performances of Li-S and Li-Se batteries by inhibiting the polysulfides/polyselenides shuttle phenomenon as well as catalyzing them toward quick redox conversions. We also briefly include the drawbacks and bottlenecks of this kind of material when used in Li-S and Li-Se batteries

A long-life and safe lithiated graphite-selenium cell with competitive gravimetric and volumetric energy densities

Lithium-selenium (Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with high Se content, high Se loading, and high density is employed. The main obstacles are the sluggish conversion kinetics of the dense Se cathodes and the continuous deterioration of the Li-metal anodes. Here, by introducing an acetonitrile (AN)-based electrolyte and replacing the Li electrode with a lithiated graphite, we successfully build a hybrid conversion-intercalation system using a high-content (80 wt%), decent-loading (3.0 mg cm−2), and low-porosity (44%) Se cathode. The as-designed lithiated graphite||Se (LG||Se) cell demonstrated a high Se utilization (97.4%), a long cycle life (3000 cycles), and an ultrahigh average Coulombic efficiency (99.98%). The cell also works well under lean-electrolyte (2 μL mg−1) condition and shows outstanding safety performance in the nail-penetrating test. The combination affords the competitive comprehensive performances, including high volumetric and gravimetric energy densities, long cycling life, and superb safety of the LG||Se cell. In addition, with a newly-designed three-electrode pouch cell, the lithiation of the graphite anodes could be done with an in-situ lithiation process, indicating the high potential of the as-proposed LG||Se cell for the practical applications.

Three-Dimensional Ordered Porous Nanostructures for Lithium-Selenium Battery Cathodes That Confer Superior Energy-Storage Performance.

Lithium-selenium (Li-Se) batteries suffer from the problems of polyselenides dissolution and volume expansion of active materials during the charge/discharge process. Moreover, the heavy atomic mass of selenium atoms limits the capacitive property of a Li-Se battery. Porous materials as the host for selenium particles reported by previous research studies are often disordered in pore structure and nonuniform in pore size. Herein, we report that a three-dimensional (3D) nitrogen-doped carbon photonic crystal (NCPC) with an ordered, interconnected structure was synthesized via a simple method to be the host of active materials. In addition, we prepared a Se-rich Se1-xSx by introducing a small amount of sulfur into a selenium ring to reduce the molecular mass but still keep the high electronic conductivity. As cathodes for a Li-Se battery, amorphous Se-rich Se1-xSx@NCPC composites exhibited high electrochemical performance with a specific capacity of 692 mA h g-1 at 0.1 Ag1-, an excellent rate capability of 526 mA h g-1 at 3 Ag1-, and an outstanding cycling property with an ultralow decay rate of 0.0132% per cycle at 0.6 Ag1- over 1000 cycles. Moreover, the pouch cell of Se1-xSx@NCPC composites also showed a good property with an energy of 253 Wh kg-1 at 0.1 Ag1- and an outstanding rate energy of 192 Wh kg-1 at 1.5 Ag1-, manifesting great potential in practical application.

The synergistic effects of nanoporous fiber TiO2 and nickel foam interlayer for ultra-stable performance in lithium-selenium batteries

Selenium is an attractive choice of cathode material for lithium-ion batteries because of its high electronic conductivity and high theoretical volumetric capacity. In this report, a Se-TiO2 cathode with a nickel foam interlayer has been designed and tested for lithium-selenium batteries. In this particular architecture, selenium is first mixed with TiO2 nanofibers to form a Se-TiO2 composite by a melt-diffusion process. Next, a nickel foam foil (NFF) is introduced as an interlayer between the electrode and separator. The synthesized Se-TiO2/NFF exhibits reversible discharge capacity of 600.4 mAh g−1 at 0.5C (1C = 675 mA g−1) after 200 cycles, and delivers a discharge capacity as high as 321.3 mAh g−1 even at 30C. This superior electrochemical performance can be ascribed to the synergetic adsorption and fixation of TiO2 and NFF.

State-Of-The-Art and Future Challenges in High Energy Lithium-Selenium Batteries.

Li-chalcogen batteries, especially the Li-S batteries (LSBs), have received paramount interests as next generation energy storage techniques because of their high theoretical energy densities. However, the associated challenges need to be overcome prior to their commercialization. Elemental selenium, another chalcogen member, would be an attractive alternative to sulfur owing to its higher electronic conductivity, comparable capacity density, and moreover, excellent compatibility with carbonate electrolytes. Unlike LSBs, the research and development of Li-Se batteries (LSeBs) have garnered burgeoning attention but are still in their infant stage, where a comprehensive yet in-depth overview is highly imperative to guide future research. Herein, a critical review of LSeBs, in terms of the underlying mechanisms, cathode design, blocking layer engineering, and emerging solid-state electrolytes is provided. First, the electrolyte-dependent electrochemistry of LSeBs is discussed. Second, the advances in Se-based cathodes are comprehensively summarized, especially highlighting the state-of-the-art Sex Sy cathodes, and mainly focusing on their structures, compositions, and synthetic strategies. Third, the versatile separators/interlayers optimization and interface regulation are outlined, with a particular focus on the emerging solid-state electrolytes for advanced LSeBs. Last, the remaining challenges and research orientations in this booming field are proposed, which are expected to motivate more insightful works.

Understanding the anchoring and catalytic effect of the Co@C2N monolayer in lithium-selenium batteries: a first-principles study.

The practical applications of lithium-selenium (Li-Se) batteries are impeded due to the low utilization of active selenium, sluggish kinetics, and volume change. The development of highly efficient host materials to suppress high-order polyselenide shuttling and accelerate Li2Se conversion is essential for Li-Se batteries. Herein, a theoretical design of a Co@C2N monolayer as a host material for ultra-high areal capacity Li-Se batteries is proposed by first-principles calculations. The investigations of the lowest energy configurations, binding energies, and the charge transfer indicate that the Co@C2N monolayer could alleviate the reciprocating motion of high-order polyselenides and improve the cycling performance. Further electronic property calculations show that the semi-metallic characteristics of the Co@C2N monolayer material are retained even after chemical adsorption with Se8 or Li2Sen molecules, which is beneficial for the utilization of active selenium. In addition, the crucial catalytic role of the Co@C2N monolayer is investigated and the results indicate that the Co@C2N monolayer could facilitate the formation and decomposition of Li2Se molecules during the discharge and charge processes. Our present work would not only provide a deep understanding on the anchoring and catalytic effect of the Co@C2N monolayer, but also demonstrate a general principle for the rational design and screening of advanced materials for high energy density Li-Se batteries.

Unraveling the superior anchoring of lithium polyselenides to the confinement bilayer C2N: an efficient host material for lithium-selenium batteries.

Carbonaceous materials with pores or bilayer spaces are a kind of potential host material to confine polyselenide diffusion and mitigate the shuttling effect. In the present work, a theoretical design of bilayer C2N (bi-C2N) as an efficient host material for lithium-selenium (Li-Se) batteries was explored by first-principles calculations. AA- and AB-stacking bilayer C2N could alleviate the dissolution of high-order polyselenides through a synergistic effect of physical confinement and strong Li-N bonds. Lithium polyselenides prefer to anchor on AA- and AB-stacking bilayer C2N instead of the commonly used electrolytes, showing their capabilities in suppressing the shuttle effect. Charge transfer occurs from Se8 and Li2Sen molecules (LiPSes) to AA- and AB-stacking bilayer C2N, giving rise to the formation of strong Li-N bonds. The AA- and AB-stacking LiPSes@C2N systems possess high electrical conductivities, which is beneficial for high electrochemical performance. In addition, the reversible conversion mechanisms of Li2Sen in the AA- and AB-stacking bilayer C2N are also investigated through the energy changes and decomposition reaction of the Li2Se molecule, and the results indicate that AA- and AB-stacking bilayer C2N facilitate the formation and decomposition of Li2Se by decreasing the active energy barriers and improving the selenium utilization rates. Our present work could shed some light on a possible strategy for designing highly efficient bilayer host materials for high performance Li-Se batteries.

Weaving 3D highly conductive hierarchically interconnected nanoporous web by threading MOF crystals onto multi walled carbon nanotubes for high performance Li–Se battery

Weaving 3D highly conductive interconnected hierarchically nanoporous web by threading MOF crystals onto multi walled carbon nanotubes for high performance lithium–selenium battery. • Pure MOF materials in Li–Se battery with highly superior performance. • 3D highly conductive hierarchical porous MIL-68 (Al)@MWCNTs web. • Novel Se cathode configurations. • Weaving the 3D highly conductive hierarchically interconnected nanoporous web. • Threading microporous metal organic framework MIL-68(Al) crystals. Lithium–selenium (Li–Se) battery has attracted growing attention. Nevertheless, its practical application is still impeded by the shuttle effect of the formed polyselenides. Herein, we report in-situ hydrothermal weaving the three-dimensional (3D) highly conductive hierarchically interconnected nanoporous web by threading microporous metal organic framework MIL-68(Al) crystals onto multi-walled carbon nanotubes (MWCNTs). Such 3D hierarchically nanoporous web (3D MIL-68 (Al)@MWCNTs web) with a very high surface area, a large amount of micropores, electrical conductivity and elasticity strongly traps the soluble polyselenides during the electrochemical reaction and significantly facilitates lithium ion diffusion and electron transportation. Molecular dynamic calculation confirmed the strong affinity of MIL-68 (Al) for the adsorption of polyselenides, quite suitable for Li–Se battery. Their hexahedral channels (1.56 nm) are more efficient for the confinement of polyselenides and for the diffusion of electrolytes compared to their smaller triangular channels (0.63 nm). All these excellent characteristics of 3D MIL-68 (Al)@MWCNTs web with suitable confinement of a large amount of selenium and the conductive linkage between MIL-68(Al) host by MWCNTs result in a high capacity of 453 mAh/g at 0.2C with 99.5% coulombic efficiency after 200 cycles with significantly improved cycle stability and rate performance. The 3D MIL-68 (Al)@MWCNTs web presents a good performance in Li–Se battery in term of the specific capacity and cycling stability and also in terms of rate performance compared with all the metal–organic framework (MOF) based or MOF derived porous carbons used in Li–Se battery.

Electrochemical Activation for Improved Cycle Life of Li-Se Batteries

Recently, the lithium-selenium (Li-Se) batteries have received enormous interest as a promising candidate for next-generation rechargeable batteries. Although selenium is similar to sulfur because they belong to the same group (chalcogenides), Li-Se battery has an advantage beyond lithium-sulfur batteries. Selenium is less reactive and more controllable in an electrochemical cell. Moreover, it has a much higher electrical conductivity than sulfur, which enables high utilization of selenium. However, one problem is the dissolution of lithium polyselenides. The lithium polyselenides aggregate at the cathode surface, resulting in increased cell impedance. To solve this problem, many experiments have been suggested but they were difficult to conduct. Herein, a simple and facile method is introduced to improve cycle performance. Before the fully discharge process, the Li-Se cell was activated electrochemically. This activation leads to a significant improvement in cycle performance by the redistribution of selenium on the electrode.

A review on electronically conducting polymers for lithium-sulfur battery and lithium-selenium battery: Progress and prospects

Lithium-sulfur (Li-S) batteries and lithium-selenium (Li-Se) batteries, as environmental protection energy storage systems with outstanding theoretical specific capacities and high energy densities, have become the hotspots of current researches. Besides, elemental S (Se) raw materials are widely sourced and their production costs are both low, which make them considered one of the new generations of high energy density electrochemical energy storage systems with the most potential for development. However, poor conductivity of elemental S/Se and the notorious “shuttle effect” of lithium polysulfides (polyselenides) severely hinder the commercialization of Li-S/Se batteries. Thanks to the excellent electrical conductivity and strong absorption of lithium polysulfide (polyselenide) about electronically conducting polymer, some of the above thorny problems have been effectively alleviated. The review presents the fundamental studies and current development trends of common electronically conducting polymers in various components of Li-S/Se batteries, which involves polyaniline (PANI) polypyrrole (PPy), and polythiophene (PTh) with its derivatives, e.g. polyethoxythiophene (PEDOT) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). Finally, the review not only summarizes the research directions and challenges facing the application of electronically conducting polymers, but also looks forward to the development prospects of them, which will provide a way for the practical use of electronically conducting polymers in Li-S/Se batteries with outstanding electrochemical properties in the short run.

High-power lithium\u2013selenium batteries enabled by atomic cobalt electrocatalyst in hollow carbon cathode

Selenium cathodes have attracted considerable attention due to high electronic conductivity and volumetric capacity comparable to sulphur cathodes. However, practical development of lithium-selenium batteries has been hindered by the low selenium reaction activity with lithium, high volume changes and rapid capacity fading caused by the shuttle effect of polyselenides. Recently, single atom catalysts have attracted extensive interests in electrochemical energy conversion and storage because of unique electronic and structural properties, maximum atom-utilization efficiency, and outstanding catalytic performances. In this work, we developed a facile route to synthesize cobalt single atoms/nitrogen-doped hollow porous carbon (CoSA-HC). The cobalt single atoms can activate selenium reactivity and immobilize selenium and polyselenides. The as-prepared selenium-carbon (Se@CoSA-HC) cathodes deliver a high discharge capacity, a superior rate capability, and excellent cycling stability with a Coulombic efficiency of ~100%. This work could open an avenue for achieving long cycle life and high-power lithium-selenium batteries.

High stable rate cycling performances of microporous carbon spheres/selenium composite (MPCS/Se) cathode as lithium–selenium battery

Loading selenium (Se) into microporous carbon spheres (MPCS) for the use as a cathode material is an efficient method for reducing the volume expansion and dissolution of polyselenides in the lithium-selenium (Li–Se) batteries during cycling. In this study, we produced MPCSs from glucose using a simple and efficient hydrothermal synthesis method, followed by activation of the MPCS with KOH. Selenium particles were homodispersed in the micropores of MPCS by a typical melt-diffusion process. The obtained MPCS/Se composites used as a cathode of Li–Se batteries show high Se loading of nearly 45%, and high capacities as well as stable cycling performance in both carbonate-based LiPF6 electrolyte (565 mAh g−1 at 1 C after 500 cycles) and ether-based LiTFSI electrolyte (480 mAh g−1 at 1 C after 500 cycles). Notably, an outstanding rate capability in the carbonate-based electrolyte and a coulombic efficiency of nearly 100% in both types of electrolytes were observed. The microporous structure of the MPCS material with high conductivity contributes to the excellent electrochemical properties and rate capability, effectively alleviating volume expansion and suppressing dissolution of polyselenides.

Lignin derived hierarchical porous carbon with extremely suppressed polyselenide shuttling for high-capacity and long-cycle-life lithium–selenium batteries

A low-cost scalable strategy is developed to fabricate lignin derived hierarchical porous carbon as a high-loading Se host. When combined with carbonate-based electrolyte, the high-capacity and long-term cycling Li–Se batteries were obtained. Lithium–selenium (Li–Se) batteries have attracted considerable attentions for next-generation energy storage systems owing to high volumetric capacity of 3265 mAh cm −3 and excellent electronic conductivity (~10 −5 S cm −1 ) of selenium. However, the shuttling effect and capacity fading prevent their wide applications. Herein we report a low-cost strategy for scalable fabrication of lignin derived hierarchical porous carbon (LHPC) as a new high-loading Se host for high-capacity and long-term cycling Li–Se batteries in carbonate electrolyte. The resulting LHPC exhibits three-dimensional (3D) hierarchically porous structure, high specific surface area of 1696 m 2 g −1 , and hetero-atom doping (O, S), which can effectively confine the Se particles into the micropores, and meanwhile, offer effective chemical binding sites for selenides from hetero-atoms (O, S). As a result, our Li–Se batteries based on Se@LHPC demonstrate high capacity of 450 mAh g −1 at 0.5 C after 500 cycles, with a low capacity fading rate of only 0.027%. The theoretical simulation confirmed the strong affinity of selenides on the O and S sites of LHPC effectively mitigating the Se losing. Therefore, our strategy of using lignin as the low-cost precursor of hierarchically porous carbon for high-loading Se host offers new opportunities for high-capacity and long-life Li–Se batteries.

Rational structure designs of 2D materials and their applications toward advanced lithium-sulfur battery and lithium-selenium battery

Lithium-sulfur (Li-S) and lithium-selenium (Li-Se) batteries have gradually triggered enormous attention in the field of secondary energy conversion and storage due to excellent theoretical capacities and advanced theoretical energy densities, which are nearly an order of magnitude higher than widely used lithium ion battery. But the commercialization processes of Li-S/Se batteries are slow due to the poor conductivity of elemental S/Se and insoluble low-order lithium polysulfides (polyselenides), severe “shuttle effect” of soluble high-order lithium polysulfides (polyselenides) and slow reaction kinetics during the process of redox reaction. Nowadays, the rationally designed two dimensional (2D) materials in the compositions of Li-S/Se batteries have presented conspicuous merits and can greatly enhance the electrochemical performances of the batteries. This review firstly highlights the distinctive structural merits of various 2D materials for advanced Li-S/Se cells. Then an overview of recent advances in the designs and preparations of different 2D materials with well-designed shapes, tailored structures, selective chemical constituents and their corresponding electrochemical properties combining the physical confinement, chemical adsorption, catalytic effect et al.. Finally, some challenges and viewpoints in this field are also discussed. The comprehensive review will help researchers to well learn rational designs including modification based on structure and engineering of 2D materials for effectively enhancing electrochemical performances of Li-S/Se cells, which eventually lead the batteries to be a practically commercial applications for power source.

Molten Lithium Battery for Space Applications

Solid-state electrolytes (SEs) have gained much interest lately as a potential for mitigating the various issues inherent in a most energy dense lithium metal (anode) based batteries such as lithium ion, lithium sulfur (Li-S), and lithium oxygen. Notable high energy next generation cathodes such as sulfur have their own issues with a liquid electrolyte based system, where the polysulfides discharge product dissolve into the electrolyte causing both: a loss of cathode active material and an unwanted shuttling of the polysulfides over the polymer separator to the lithium anode limiting their practical use. Moreover, the formation of lithium dendrites in lithium batteries is yet another challenging issue that not only limits battery cycle-life but also poses safety risks. The use of SEs can potentially address most of the issues related to next generation lithium batteries such as Li-S batteries, but getting rid of dendrite issues may not be addressed completely. One way to eliminate the dendrite issue is to use molten lithium as an anode.The National Aeronautics and Space Administration (NASA) has an ambitious plan to explore one of the most challenging planets in our solar system: Venus. The surface temperature of Venus can reach as high as 465°C and at same time, the Venus atmosphere is filled with corrosive gases such as carbon dioxide, sulfur dioxide, carbon monoxide, etc. A battery for such a challenging space mission can be built only if battery components (especially the electrolyte) is stable beyond 500°C and must be stable with molten lithium and sulfur electrodes for at least hours or days if not months—longer is better. Last but not the least, yet another challenge is containment of gaseous sulfur inside the battery container at such a high temperature. The potential to replace sulfur with selenium may mitigate the issue but at cost of reduced energy density.Under a NASA funded project, the University of Dayton Research Institute (UDRI) is developing molten lithium sulfur (Li-S) or lithium-selenium (Li-Se) batteries with the help of a high temperature solid ceramic electrolyte (SCE) that can enable a operating temperature >465°C for several hours. UDRI has been working on a high temperature SCE such as phosphate-based Li1+ xAlxGe2- x(PO4)3 (LAGP) ceramic electrolyte material1 that is stable beyond 500°C and also shows broad electrochemical window (up to 5V) that is sufficient for a molten Li-S or Li-Se battery operation; provided LAGP is stable with Li and S or Se in such harsh conditions and temperature. Unfortunately, LAGP is not stable with Li (forms a highly resistive interface layer between LAGP and electrode) and its stability with sulfur or Se, needs to be determined.Under the NASA project, UDRI has been developing interface materials between LAGP and electrodes for Li-S and Li-Se cells that can be stable at wide temperature range (room temperature to 500°C). The presentation will include progress on high temperature (up to 465°C) i) SCE, ii) SCE/Li interface materials, iii) SCE/S interface material, iv) SCE/Se interface material, v) impedance and open circuit voltage of Li-S or Li-Se cells at 465°C, and vi) cycle-life of Li-S or Li-Se cells at 465°C. To the authors knowledge, there is no such report (molten Li-S or Li-Se cells that can function at 465°C) that exists in literature.B. Kumar, D. Thomas, J. Kumar, “Space-Charge-Mediated Superionic Transport in Lithium Ion Conducting Glass–Ceramics,” J. Electrochem. Soc. 156, A506 (2009)

Selenium-Infused Ordered Mesoporous Carbon for Room-Temperature All-Solid-State Lithium-Selenium Batteries with Ultrastable Cyclability.

Selenium with a similar reaction mechanism with sulfur and a much higher electronic conductivity is considered to be a promising cathode for all-solid-state rechargeable batteries. Herein, selenium-infused ordered mesoporous carbon composites (Se/CMK-3) are successfully prepared by a melt-diffusion method from a ball-milled mixture of Se and CMK-3 (Se-CMK-3). Furthermore, their electrochemical performances are evaluated in all-solid-state lithium-selenium batteries at room temperature. Typically, Li/75%Li2S-24%P2S5-1%P2O5/Li10GeP2S12/Se/CMK-3 all-solid-state lithium-selenium batteries exhibit high reversible capacity of 488.7 mAh g-1 at 0.05 C after 100 cycles. Even being cycled at 0.5C, it still maintains a discharge capacity of 268.7 mAh g-1 after 200 cycles. The excellent electrochemical performances could be attributed to the enhanced electronic/ionic conductivities and structural integrity with the addition of the CMK-3 matrix.

Covalent Selenium Embedded in Hierarchical Carbon Nanofibers for Ultra-High Areal Capacity Li-Se Batteries.

SummaryLithium selenium (Li-Se) batteries have attracted increasing interest for its high theoretical volumetric capacities up to 3,253 Ah L−1. However, current studies are largely limited to electrodes with rather low mass loading and low areal capacity, resulting in low volumetric performance. Herein, we report a design of covalent selenium embedded in hierarchical nitrogen-doped carbon nanofibers (CSe@HNCNFs) for ultra-high areal capacity Li-Se batteries. The CSe@HNCNFs provide excellent ion and electron transport performance, whereas effectively retard polyselenides diffusion during cycling. We show that the Li-Se battery with mass loading of 1.87 mg cm−2 displays a specific capacity of 762 mAh g−1 after 2,500 cycles, with almost no capacity fading. Furthermore, by increasing the mass loading to 37.31 mg cm−2, ultra-high areal capacities of 7.30 mAh cm−2 is achieved, which greatly exceeds those reported previously for Li-Se batteries.

Functionalized MXenes as effective polyselenide immobilizers for lithium-selenium batteries: a density functional theory (DFT) study.

The practical applications of lithium selenium (Li-Se) batteries are impeded primarily due to the dissolution and migration of higher-order polyselenides (Li2Sen) into the electrolyte (known as the shuttle effect) and inactive deposition of lower-order polyselenides. The high electrical conductivity and mechanical strength of MXenes make them a suitable candidate to provide adequate anchoring to prevent polyselenide dissolution and improved electrochemical performance. Herein, we used density functional theory (DFT) calculations to understand the binding mechanism of Li2Sen on graphene and surface-functionalized Ti3C2 MXenes. We used graphene as a reference material to assess Li2Sen binding strengths on functionalized Ti3C2X2 (where X = S, O, F, and Cl). We observed that Ti3C2S2 and Ti3C2O2 exhibit superior anchoring behavior compared to graphene, Ti3C2F2, and Ti3C2Cl2. The calculated Li2Sen adsorption strengths, provided by S- and O-terminated Ti3C2, are greater than those of the commonly used ether-based electrolyte, which is a requisite for effective suppression of Li2Sen shuttling. Ti3C2X2 and graphene with adsorbed Li2Sen retain their structural integrity without chemical decomposition. Density of states (DOS) analysis demonstrates that the conductive behavior of Ti3C2X2 is preserved even after Li2Sen adsorption, which can provide electronic pathways to stimulate the redox electrochemistry of Li2Sen. Overall, our unprecedented simulation results reveal superior anchoring behavior of Ti3C2S2 and Ti3C2O2 for Li2Sen adsorption, and this developed understanding can be leveraged for designing carbon-free Ti3C2 MXene-based selenium cathode materials to boost the electrochemical performance of Li-Se batteries.

Novel hierarchical porous carbon prepared by a one-step template route for electric double layer capacitors and Li–Se battery devices

Low-cost hierarchical porous carbon materials with a controllable structure for supercapacitors and lithium selenium batteries.

Metal organic framework-derived carbon nanosheets with fish-scale surface morphology as cathode materials for lithium–selenium batteries

Tailoring of carbon matrix with reasonable structures is considered to be an effective way to achieve excellent electrochemical performance of lithium−selenium batteries. For the first time, hierarchically porous carbon nanosheets with a fish-scale like surface morphology are prepared using self-assembled metal-organic frameworks (MOFs) as template and carbon source. The carbon nano-architecture has a large specific surface area and well-defined nanostructure. When evaluated as a cathode for lithium-selenium batteries, the carbon/selenium composite demonstrates high specific capacity and excellent cycling performance. At a current rate of 2 C, a discharge capacity of 311.8 mAh g−1 is achieved after 200 cycles. Moreover, even at the current rate of 8 C, the charge-discharge efficiency is maintained at 99.9% after 1000 cycles. The enhanced electrochemical performance is closely related to their well-defined nanostructures, which not only provides stable electronic and ionic transfer channels, but also plays a key role as a strong absorbent to retain lithium polyselenides and accommodate volume variation during the charge–discharge process.