Improving lithium–sulfur battery performance via a carbon-coating layer derived from the hydrothermal carbonization of glucose

Abstract

Sulfur possesses high specific capacity as a rechargeable lithium battery cathode. However, the commercial applications of sulfur cathode are limited by the poor electronic/ionic conductivity of elemental sulfur and polysulfides, volume expansion of sulfur during discharge process, and the high solubility of long-chain lithium polysulfides (Li2Sn, 4 ≤ n ≤ 8). Herein, we design a core-shell structure composed of active carbon (AC) and an amorphous carbon-coating layer to encapsulate the sulfur in the carbon matrix. The carbon-coating layer obtained from the hydrothermal carbonization of glucose can effectively entrap the polysulfides. Furthermore, the composite matrix provides a conducting framework serving as an electrochemical reaction chamber for the sulfur cathode. After wrapped AC-S with an amorphous carbon layer, the obtained composite cathode can effectively confine the polysulfides and buffer the volume change. Consequently, the resulting composite cathode possesses a high specific capacity, good rate capability, and stable cycling performance. At 0.2 A g -1 current density, the as-prepared carbon-coated AC-S composite cathode shows a high specific discharge capacity of 1103 mAh g -1 . At a current density of 0.8 A g -1 and 1.6 A g -1 , the composite cathode exhibites 75% capacity retention over 150cycles. The coulombic efficiency of the cell remains at approximately 95%.

High‐Sulfur‐Content Graphene‐Based Composite through Ethanol Evaporation for High‐Energy Lithium‐Sulfur Battery

“…[24,25] The most common solution to overcome the lowe lectrical conductivity and the spreado ft he lithium polysulfide through the cell is the use of ac arbonaceous matrix that can increase the electronic conductivity through the electrode, acting, at the same time, as ar eactionh ost. [26,27] Many sulfur-carbon composites have been proposed to solve these issues, through the use of carbonn anotubes, [28] mesocarbon microbeads (MCMB carbon), [29] amorphous carbon, [30] graphite, [31] graphene oxide, [32] or reduced graphene oxide, [33] enhancingt he performance and applicability of the lithium-sulfur battery in terms of stability,c ycle life, and energy density. [34,35] However, most of the preparation pathways of the cathode active materials are complex and involve expensive procedures, hindering the scalability of these material solutionsb eyond lab-scale prototypes.…”

Relevant Features of a Triethylene Glycol Dimethyl Ether-Based Electrolyte for Application in Lithium Battery

“…[29][30][31] However, glyme-based electrolytes have shown poor passivation properties of the lithium metal surface, which lead to remarkable increase of cell polarization and interface resistance upon cycling, as well as to excessive electrolyte decomposition. [32][33][34] The addition of lithium nitrate (LiNO3) may actually improve the lithium/electrolyte interface by formation upon cycles of a stable passivation film containing nitrate moieties, such as RCH2NO2, LiNxOy and LixN, 35 thus leading to proper battery operation and limiting dendrite formation. [36][37][38] Glyme-based electrolytes have been widely investigated for Li-S 10,31,[39][40][41][42][43][44][45] and Li-O2; [46][47][48][49][50] however, they may be also used for intercalation cathode materials, although limited papers demonstrated good cell performances.…”

Carbon Composites for a High‐Energy Lithium–Sulfur Battey with a Glyme‐Based Electrolyte

“…Furthermore, the low conductivity of the sulfur cathode significantly depresses the delivered capacity and the rate capability in the lithium cell due to increased polarization during the lithium–sulfur electrochemical process . Infiltrating sulfur into several kinds of carbonaceous materials, such as graphite layers, amorphous carbon, carbon nanotubes (CNTs), nanosheets, and hierarchical structured carbons, has actually led to great improvement of the cycling stability; electron and ion conductivity; and, consequently, the rate capability and cycle life of sulfur cathodes in lithium cells . However, most studies reporting sulfur composites, mainly based on carbons, involved complex procedures for the preparation of active material that might actually lead to a rapid increase in the economic impact of the cell.…”