of 2600 W h kg −1 . [2] However, the development of Li-S battery is plagued by several challenges that must be addressed. First of all, sulfur is both electrically and ionically insulating, as well as its lithiated product Li 2 S, which necessitates the incorporation of sulfur into a conductive matrix. [3] In addition, quite different from traditional Li intercalation compounds, sulfur suffers electrochemical dissolution and deposition reactions and generates a series of polysulfide (PS n ) species, of which highorder PS n (4 ≤ n ≤ 8) are soluble in etherbased electrolyte and prone to diffuse to the anode side for reducing deeply to the insoluble Li 2 S 2 and Li 2 S. Correspondingly, Li 2 S 2 and Li 2 S could migrate back to the cathode and be oxidized. [4] The so-called "shuttle effect" leads to an irreversible loss of active sulfur and a fast degradation of cycle stability. Consequently, during the redox reaction, the repetitive dissolution and deposition reactions of the PS n passivate both cathode and anode gradually, resulting in a considerable increase of the electrode impedance. [5] Moreover, the density difference between sulfur (2.07 g cm −3 ) and Li 2 S (1.66 g cm −3 ) leads to a significant volume expansion, which is adverse to the mechanical strength of sulfur cathode. [2c,6] All of these factors restrict severely the electrochemical performance of sulfur cathode.To date, upsurge of attention has been paid in fabricating high-efficiency and stable sulfur cathode, the vital component of the Li-S battery. These efforts focus on developing novel nanocomposites by incorporating sulfur into various host materials, such as carbonaceous materials (including porous carbon, [7] hollow carbon spheres, [8] carbon nanotube/fibers, [9] graphene and its derivatives, [10] or hybrid carbon hosts, [11] ) conducting polymers, [12] metal oxides, [13] and metal or covalent organic frameworks. [14] These host materials are expected to promote the electron transfer, accommodate the volumetric expansion, and trap the soluble PS n . In this respect, carbonaceous materials are proven to be a promising option owing to their excellent electrical conductivity, outstanding mechanical strength, and multiple architectures. Typically, the members with higherdimensional contrast structure are endowed with exclusive superiority in compositing with sulfur. In detail, carbon nanotubes (CNTs) possess classic 1D structure and exhibit a self-weaving Carbon materials have attracted extensive attention as the host materials of sulfur for lithium-sulfur battery, especially those with 3D architectural structure. Here, a novel 3D graphene nanosheet-carbon nanotube (GN-CNT) matrix is obtained through a simple one-pot pyrolysis process. The length and density of CNTs can be readily tuned by altering the additive amount of carbon source (urea). Specifically, CNTs are in situ introduced onto the surface of the graphene nanosheets (GN) and show a stable covalent interaction with GN. Besides, in the GN-CNT matrix, cobalt nanoparticles with...
Lithium-sulfur (Li-S) batteries are regarded as the promising next-generation energy storage device due to the high theoretical energy density and low cost. However, the practical application of Li-S batteries is still limited owing to the cycle stability of both the sulfur cathode and lithium anode. In particular, the instability in the bulk and at the surface of the lithium anode during cycling becomes a huge obstacle for the practical application of Li-S battery. Herein, a Li-rich lithium-magnesium (Li-Mg) alloy is investigated as an anode for Li-S batteries, based on the consideration of improving the stability in the bulk and at the surface of the lithium anode. Our experimental results reveal that the robust passivation layer is formed on the surface of the Li-Mg alloy anode, which is helpful to reduce side reactions, and enable the smooth surface morphology of anode during cycling. Meanwhile, the mixed electron and Li-ion conducting matrix of the Li-poor Li-Mg alloy as a porous skeleton structure can also be formed after delithiation, which can guarantee the structural integrity of the anode in the bulk during Li stripping/plating process. Therefore, the Li-rich Li-Mg alloy is demonstrated to be a very promising anode material for Li-S battery.
ising candidates for the next generation of high energy storage system. Since proposed in the 1960s, [3] Li-S battery experienced an infancy stage in 1970-1990s, when researchers devoted to the fundamental redox reactions of sulfur in various electrolytes, [4] and a flourishing period after 2000 when high performance was achieved through sulfur/carbon (S/C) cathode and sulfurized-polyacrylonitrile (SPAN) cathode in ether-and carbonatebased electrolytes, respectively. [5] After 2009, great efforts have been made to further enahnce Li-S battery, including fabricating conductive cathode, [6] incorporating electrocatalyst, [7] modifying separator, [8] optimizing electrolyte, [9] and protecting lithium anodes. [10] The rational design of electrode structure with various carbon materials (1D, 2D, and 3D) greatly boosts the electrochemical performance of sulfur cathode. [11] Although the cycle stability is still struggling with 100 cycles, the gravimetric energy density (W G) of Li-S pouch cells has improved remarkably to promote the applications in which weight matters more than longevity. For example, Sion Power, a pioneer corporation in Li-S battery technology, has developed several prototypical Li-S cells with energy density of 350 Wh kg −1 /325 Wh L −1 for powering Airbus's Zephyr 7 drone for an 11-day nonstop flight in 2014. [12] Oxis Energy, another manufacture of Li-S battery, announced a new target of 500 Wh kg −1 in the near future after achieving 400 Wh kg −1 / 300 Wh L −1 for e-Buses, trucks, and marine applications. [13] Research institutions from China have also reported pouch Li-S cells with the energy density up to 400-600 Wh kg −1 for the potential application in unmanned aerial vehicle. [14] It is remarkable that the W G of Li-S battery has exceeded that of the best Li-ion batteries (250-300 Wh kg −1) with Ni-rich oxide cathode from Contemporary Amperex Technology Co., Ltd. (CATL), a giant manufacture of Li-ion batteries (Figure 1). With such great advantages, Li-S battery is possible to compete with commercial Li-ion batteries in specific field where high W G is the primary concern. Despite the attractive high W G , Li-S battery pales in comparison with Li-ion batteries in terms of volumetric energy density (W V). [18] Figure 1 compares W V and W G between Li-S and Li-ion batteries. With Ni-rich metal oxide as cathode, Li-ion batteries have already reached 700 Wh L −1 and can even exceed 1000 Wh L −1 for W V when coupling with high capacity Lithium-sulfur (Li-S) batteries hold the promise of the next generation energy storage system beyond state-of-the-art lithium-ion batteries. Despite the attractive gravimetric energy density (W G), the volumetric energy density (W V) still remains a great challenge for the practical application, based on the primary requirement of Small and Light for Li-S batteries. This review highlights the importance of cathode density, sulfur content, electroactivity in achieving high energy densities. In the first part, key factors are analyzed in a model on negative/positive ...
Lithium-sulfur battery is recognized as one of the most promising energy storage devices, while the application and commercialization are severely hindered by both the practical gravimetric and volumetric energy densities due to the low sulfur content and tap density with lightweight and nonpolar porous carbon materials as sulfur host. Herein, for the first time, conductive CoOOH sheets are introduced as carbon-free sulfur immobilizer to fabricate sulfur-based composite as cathode for lithium-sulfur battery. CoOOH sheet is not only a good sulfur-loading matrix with high electron conductivity, but also exhibits outstanding electrocatalytic activity for the conversion of soluble lithium polysulfide. With an ultrahigh sulfur content of 91.8 wt% and a tap density of 1.26 g cm −3 , the sulfur/CoOOH composite delivers high gravimetric capacity and volumetric capacity of 1199.4 mAh g −1 -composite and 1511.3 mAh cm −3 at 0.1C rate, respectively. Meanwhile, the sulfurbased composite presents satisfactory cycle stability with a slow capacity decay rate of 0.09% per cycle within 500 cycles at 1C rate, thanks to the strong interaction between CoOOH and soluble polysulfides. This work provides a new strategy to realize the combination of gravimetric energy density, volumetric energy density, and good electrochemical performance of lithium-sulfur battery.
A lithium anode protected with a porous Al2O3layer is beneficial for improving the cycle stability and capacity retention of a lithium–sulfur battery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.