While backless freestanding 3D electrode architectures for batteries with high loading sulfur have flourished in the recent years, the more traditional and industrially turnkey 2D architecture has ...not received the same amount of attention. This work reports a spray‐dried sulfur composite with large intrinsic internal pores, ensuring adequate local electrolyte availability. This material offers good performance with a electrolyte content of 7 µL mg−1 at high areal loadings (5–8 mg cm−2), while also offering the first reported 2.8 µL mg−1 (8 mg cm−2) to enter into the second plateau of discharge and continue to operate for 20 cycles. Moreover, evidence is provided that the high‐frequency semicircle (i.e., interfacial resistance) is mainly responsible for the often observed bypassing of the second plateau in lean electrolyte discharges.
Cyclability of a low‐electrolyte‐content, high‐areal‐sulfur electrode is achieved through the development of an agglomerated structure composed of large‐scale hollow materials. Detailed in situ impedance and X‐ray diffraction analysis reveal interesting characteristics of sulfur cells operating under lean electrolyte conditions.
Despite their high theoretical energy density, the application of lithium–sulfur batteries is seriously hindered by the polysulfide shuttle and sluggish kinetics, especially with high sulfur loading ...and under low electrolyte usage. Herein, to facilitate the conversion of lithium polysulfides, nickel–boron (Ni–B) alloy nanoparticles, dispersed uniformly on carbon nanotube microspheres (CNTMs), are used as sulfur hosts for lithium–sulfur batteries. It is demonstrated that Ni–B alloy nanoparticles can not only anchor polysulfides through Ni–S and B–S interactions but also exhibit high electrocatalytic capability toward the conversion of intermediate polysulfide species. In addition, the intertwined CNT microspheres provide an additional conductive scaffold in response to the fast electrochemical redox. The enhanced redox kinetics is beneficial to improve the specific capacity and cycling stability of the sulfur cathode, based on the fast conversion of lithium polysulfides and effective deposition of the final sulfide products. Conclusively, the S/Ni–B/CNTM composite delivers a high specific capacity (1112.7 mAh gs –1) along with good cycle performance under both high sulfur loading (8.3 mg cm–2) and a lean electrolyte (3 μL mgs –1). Consequently, this study opens up a path to design new sulfur hosts toward lithium–sulfur batteries.
Elemental sulfur electrode has a huge advantage in terms of charge-storage capacity. However, the lack of electrical conductivity results in poor electrochemical utilization of sulfur and ...performance. This problem has been overcome to some extent previously by using a bare multiwall carbon nanotube (MWCNT) paper interlayer between the sulfur cathode and the polymeric separator, resulting in good electron transport and adsorption of dissolved polysulfides. To advance the interlayer concept further, we present here a self-assembled MWCNT interlayer fabricated by a facile, low-cost process. The Li–S cells fabricated with the self-assembled MWCNT interlayer and a high loading of 3 mg cm–2 sulfur exhibit a first discharge specific capacity of 1112 mAh g–1 at 0.1 C rate and retain 95.8% of the capacity at 0.5 C rate after 100 cycles as the self-assembled MWCNT interlayer facilitates good interfacial contact between the interlayer and the sulfur cathode and fast electron and lithium-ion transport while trapping and reutilizing the migrating polysulfides. The approach presented here has the potential to advance the commercialization feasibility of the Li–S batteries.
The binder used in the formulation of sulfur electrodes for Li/S batteries plays a crucial role in their electrochemical performance. In the present study, the impact of using a polyelectrolyte ...binder (poly(diallyldimethylammonium) bis(trifluromethane sulfonyl)imide) on the morphological degradation of sulfur electrodes is evaluated by in situ dilatometry, acoustic emission (AE) and synchrotron X-ray tomography (XRT), and compared to more conventional binders (poly(vinylidene difluoride) (PVdF) and carboxymethylcellulose (CMC)). The dilatometry study shows that during the initial sulfur dissolution process, the polyelectrolyte-based electrode displays a lower irreversible thickness contraction of ~16% compared to ~22% and ~31% for CMC and PVdF, respectively. This is confirmed by the XRT measurements showing a reduced thickness variation for the polyelectrolyte electrode compared to the CMC electrode. The same trend is found in the AE results, where a lower acoustic activity attributed to the rupture of the binder/carbon/sulfur network is detected during the 1st discharge plateau for the polyelectrolyte electrode. All these results confirm the major role of the binder for the Li/S system. Thanks to its multifunctionality, it impacts both the diffusion of the active material outside the electrode and the electrode integrity and therefore the conduction paths and accessible active surface for electrochemical processes.
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•The impact of the binder on the morphological change of sulfur electrodes is studied.•PVdF, CMC and cationic polyelectrolyte binders are compared.•In situ dilatometry, acoustic emission and X-ray tomography are used.•The better mechanical strength of the polyelectrolyte based electrode is highlighted.
The acquisition of stable and high-areal-capacity S cathodes over 10 mA h cm
is a critical and indispensable step to realize the high energy density configuration. However, increasing the areal ...capacity of S cathodes often deteriorates the specific capacity and stability due to the aggravated dissolution of S and diffusion of solvable polysulfides in the thick electrode. Herein, the design of a freestanding composite cathode that leverages 3D covalent binding sites and chemical adsorption environment to offer dissolution-limiting and diffusion-blocking functions of S species is reported. By employing this architecture, the coin cell exhibits excellent cycling stability and an exceptional specific capacity of 1444.3 mA h g
(13 mA h cm
), and the pouch cell configuration manifests a noteworthy areal capacity exceeding 11 mA h cm
. This performance is coupled with excellent flexibility, demonstrated through consecutive bending cycle tests, even at a sulfur loading of 9.00 mg cm
. This study lays the foundation for the development of flexible Li-S batteries with increased loading capacities and exceptional performance.
The use of functional materials is a popular strategy to mitigate the polysulfide‐induced accelerated aging of lithium–sulfur (Li‐S) batteries. However, deep insights into the role of electrode ...design and formulation are less elaborated in the available literature. Such information is not easy to unearth from the existing reports on account of the scattered nature of the data and the big dissimilarities among the reported materials, preparation protocols, and cycling conditions. In this study, model functional materials known for their affinity toward polysulfide species, are integrated into the porous sulfur electrodes at different quantities and with various spatial distributions. The electrodes are assembled in 240 lithium–sulfur cells and thoroughly analyzed for their short‐ and long‐term electrochemical performance. Advanced data processing and visualization techniques enable the unraveling of the impact of porous electrodes’ formulation and design on self‐discharge, sulfur utilization, and capacity loss. The results highlight and quantify the sensitivity of the cell performance to the synergistic interactions of catalyst loading and its spatial positioning with respect to the sulfur particles and carbon‐binder domain. The findings of this work pave the road for a holistic optimization of the advanced sulfur electrodes for durable Li–S batteries.
This research seeks to offer key insights into optimizing advanced electrodes for lithium–sulfur batteries. The study emphasizes the critical role of optimal catalyst quantity and strategic placement near sulfur particles or the carbon‐binder domain. These factors notably impact capacity retention and rate‐capability, governing the local balance between the conversion and migration rates of polysulfides.
The rapid advancement of technology and the growing need for energy storage solutions have led to unprecedented research in the field of metal-ion batteries. This perspective article provides a ...detailed exploration of the latest developments and future directions in energy storage, particularly focusing on the promising alternatives to traditional lithium-ion batteries. With solid-state batteries, lithium-sulfur systems and other metal-ion (sodium, potassium, magnesium and calcium) batteries together with innovative chemistries, it is important to investigate these alternatives as we approach a new era in battery technology. The article examines recent breakthroughs, identifies underlying challenges, and discusses the significant impact of these new frontiers on various applications–from portable electronics to electric vehicles and grid-scale energy storage. Against the backdrop of a shifting paradigm in energy storage, where the limitations of conventional lithium-ion batteries are being addressed by cutting-edge innovations, this exploration offers insights into the transformative potential of next-generation battery technologies. The article further aims to contribute to the ongoing scientific dialogue by focusing on the environmental and economic implications of these technologies.
A novel sodium ion conducting gel polymer electrolyte comprising room temperature ionic liquid, 1-ethyl 3-methyl imidazolium trifluoro-methane sulfonate (EMITf) incorporated with ethylene carbonate ...and propylene carbonate and its solution with sodium trifluoromethane sulfonate (NaTf) entrapped in poly(vinylidinefluoride-co-hexfluoropropylene) (PVdF-HFP) is prepared using solution cast technique. The gel electrolyte is obtained in the form of free-standing transparent film. The gel electrolyte offers electrical conductivity of ∼10−3Scm−1 at ∼30°C with good mechanical, thermal and electrochemical stability window. The electrical conductivity is measured as a function of temperature and found to be consistent with Vogel-Tamman-Fulcher (VTF) relationship in the temperature range from 30°C to 75°C.
Sodium ion conduction in the gel electrolyte film is confirmed from cyclic voltammetry and transport number measurements. The value of the sodium ion transport number of the ionic liquid based gel electrolyte is ∼0.19. The sodium sulfur battery with the gel electrolytes delivers the first discharge capacity of 267mAhg−1 sulfur and then it decreases with repeated charge–discharge cycles.
•A novel, free standing Na+ gel electrolyte is reported.•The gel electrolyte offers ionic conductivity ∼10 −3 S cm−1 at 30°C.•Cyclic voltammetry and transport number measurement confirms the Na+ conduction in electrolyte film.•The Na-S battery with the gel electrolyte delivers discharge capacity of 267mAhg−1 sulfur.
FB-diluted electrolyte shows low density and high ionic conductivity. The resulting cells shows a high capacity of 9.48 mAh cm−2 and excellent capacity retention under practical conditions, realizing ...high energy density of Li-S batteries.
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The mass fraction of electrolytes is the crucial factor affecting the energy density of lithium-sulfur (Li-S) batteries. Due to the high porosity within the C/S cathode, high concentration of polysulfides, and side reaction in lithiun metal anode under lean electrolyte, it is extremely challenging to improve performance while reducing the electrolyte volume. Here, we report a novel electrolyte with relatively low density (1.16 g cm−3), low viscosity (1.84 mPa s), and high ionic conductivity, which significantly promotes energy density and cyclability of Li-S batteries under practical conditions. Moreover, such electrolyte enables a hybrid cathode electrolyte interphase (CEI) and solid electrolyte interface (SEI) layer with plentiful LiF, which leads to fast kinetics of ions transport and stable cyclability even under low temperatures. Compared to Li-S batteries in electrolyte employing 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) diluent, the ultra-thick cathode (20 mg cm−2) shows a high capacity of 9.48 mAh cm−2 and excellent capacity retention of 80.3% over 191 cycles at a low electrolyte-to-sulfur ratio (E/S = 2) and negative-to-positive capacity ratio (N/P = 2.5), realizing a 19.2% improvement in energy density in coin cells (from 370 to 441 Wh kg−1) and a high energy density up to 467 Wh kg−1 in pouch cells. This study not only provides guidance for the electrolyte design but also paves the way for the development of high performance Li-S batteries under practical conditions.
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It was discovered that when the loading of the sulfur electrode is high, the utilization of the sulfur, which is controlled by the concentration of salt in the electrolyte, ...significantly increases with decreasing salt concentration.
Sulfur utilization improvement and control of dissolved lithium polysulfide (LiPS; Li2Sx, 2 < x ≤ 8) are crucial aspects of the development of lithium-sulfur (Li-S) batteries, especially in high-loading sulfur electrodes and low electrolyte/sulfur (E/S) ratios. The sluggish reaction in the low E/S ratio induces poor LiPS solubility and unstable Li2S electrodeposition, resulting in limited sulfur utilization, especially under high-loading sulfur electrode. In this study, we report on salt concentration effects that improve sulfur utilization with a high-loading cathode (6 mgsulfur cm−2), a high sulfur content (80 wt%) and a low E/S ratio (5 mL gsulfur−1). On the basis of the rapid LiPS dissolving in a low concentration electrolyte, we established that the quantity of Li2S electrodeposition from a high Li+ diffusion coefficient, referring to the reduction of LiPS precipitation, was significantly enhanced by a faster kinetic. These results demonstrate the importance of kinetic factors for the rate capability and cycle life stability of Li-S battery electrolytes through high Li2S deposition under high-loading sulfur electrode.
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