A Comprehensive Approach toward Stable Lithium–Sulfur Batteries with High Volumetric Energy Density

Abstract

across the whole electrode and suppressed LiPSs shuttling to the lithium anode are required. [8][9][10][11] Great efforts have been made to address these aforementioned issues with a primary focus on the cathode materials. Nano-carbons and graphenes with micro/ mesoporous channels are representative of early stage sulfur host materials, which provide conductivity and physical entrapment of the LiPSs. [12][13][14][15][16][17][18][19] The lack of strong interaction with the LiPSs lead to rapid capacity fading on cycling in most of these studies, however. Functionalized carbons, exemplified by graphene oxides and heteroatoms-doped carbons, demonstrate chemical entrapment of the LiPSs and enable longer-term cycling. [20][21][22][23][24] Modifications of carbons using polymers decorated with polar functional groups established another path to bind LiPSs without compromising the conductivity. [25][26][27] Departing from carbonaceous materials, inorganic metal-based materials including metal oxides, metal sulfides, metal organic frameworks, and MXene phases have been recently studied as sulfur hosts. [28][29][30][31][32][33][34][35] Their strong chemical interaction with LiPSs based on polar-polar interactions, Lewis acid-base bonding or chemical catenation plays an essential role in suppressing the shuttling. Adsorption of LiPSs results in controlled precipitation of Li 2 S and S 8 , which enhances uniform distribution of active materials. [30,36] Aside from the cathode, rationally designed electrolyte modifications and redox mediators have also shown promise in controlling polysulfide dissolution and Li 2 S deposition. [37][38][39][40] In light of the above advances, it is now also appreciated that the low volumetric energy density (ED) of many Li-S batteries still pose a concern due to two aspects: the low density of sulfur (2.07 mg cm −3 ) that is often reported with a high fraction of carbon (>40 wt%), and high electrolyte/sulfur ratios. Achieving high areal sulfur loading (>7 mg cm −2 ) with low electrolyte volume is critical to maximize the ED, but this is not the case for most reported systems to date. [41] Moreover, the challenge for high-performance thick cathodes resides in all cathode components: the individualized nanosized porous C/S composites, the polyvinylidene fluoride (PVDF) binder that lacks elasticity and insufficient interparticle conductivity. [9][10][11] In order to fabricate high-loading Li-S cathodes, two approaches have been used. One is to construct 3D conductive frameworks, [42][43][44][45][46][47] and the other is to integrate the host nanomaterials before slurry processing. [48][49][50] Pure carbon 3D networks, usually composed A comprehensive approach is reported to construct stable and high volumetric energy density lithium-sulfur batteries, by coupling a multifunctional and hierarchically structured sulfur composite with an in-situ cross-linked binder. Through a combination of first-principles calculations and experimental studies, it is demonstrated that a hybrid sulfur host composed b...

Rational Design of Binders for Stable Li‐S and Na‐S Batteries

“…For example, the dendritic structure of water-soluble polyamidoamine (PAMAM) provides a high degree of surface functionality and polarity and ensures a high interior porosity when mixed with sulfur ( Figure 3B). [33] Up to now, other covalently crosslinked binders such as self-cross-linked polyacrylamide [73] and crosslinked CMC with citric acid, [74] are also reported. It should be noted that increasing branched degrees of and molecular weights will lead to poor solubility and therefore a balance between the branches and the solubility should be considered in the synthesis.…”

An Integrated Strategy towards Enhanced Performance of the Lithium–Sulfur Battery and its Fading Mechanism

“…However,P VDF shows limitations when thick electrodes are prepared and does not accommodate the volumec hange during cycling test.F or example, when thick electrodes are prepared by using PVDF,c racks or pinholes on the electrode surface are commonly observed. [33][34][35] In the present study,t he obtained S/KB composite (85 wt %) was mixed with CMC-CA (4.5 wt %C MC as polymerm atrix and 0.5 wt %C Aa sc ross linker) and additional conductive agents (5 wt %m ulti-walled carbon nanotubes and 5wt% KB), followed by ah eat treatment at 150 8Cf or 2h,d uring which the S/KB composites were in situ bonded into CMC-CA networks. This issue is amplified for the thicker electrode, which can lead to excessive shrinkage and eventually surfacec racking during electrode drying.…”

Exploring the Effect of Increased Energy Density on the Environmental Impacts of Traction Batteries: A Comparison of Energy Optimized Lithium-Ion and Lithium-Sulfur Batteries for Mobility Applications

“…Therefore, structurally integrated battery concepts have the potential to save inactive mass. Furthermore, the other components besides the sulfur cathode, such as the lithium metal anode, separator and electrolyte and its amount, have to be optimized to meet the requirements of power, specific energy and cycle life [23][24][25][26][27][28][29].…”