Minimizing Carbon Content with Three‐in‐One Functionalized Nano Conductive Ceramics: Toward More Practical and Safer S Cathodes of Li‐S Cells

Abstract

Using porous carbon hosts in cathodes of Li‐S cells can disperse S actives and offset their poor electrical conductivity. However, such reservoirs would in turn absorb excess electrolyte solvents to S‐unfilled regions, causing the electrolyte overconsumption, specific energy decline, and even safety hazards for battery devices. To build better cathodes, we propose to substitute carbons by In‐doped SnO2 (ITO) nano ceramics that own three‐in‐one functionalities: 1) using conductive ITO enables minimizing the total carbon content to an extremely low mass ratio (~3%) in cathodes, elevating the electrode tap density and averting the electrolyte overuse; 2) polar ITO nanoclusters can serve as robust anchors toward Li polysulfide (LiPS) by electrostatic adsorption or chemical bond interactions; 3) they offer catalysis centers for liquid–solid phase conversions of S‐based actives. Also, such ceramics are intrinsically nonflammable, preventing S cathodes away from thermal runaway or explosion. These merits entail our configured cathodes with high tap density (1.54 g cm−3), less electrolyte usage, good security for flame retardance, and decent Li‐storage behaviors. With lean and LiNO3‐free electrolyte, packed full cells exhibit excellent redox kinetics, suppressed LiPS shuttling, and excellent cyclability. This may trigger great research enthusiasm in rational design of low‐carbon and safer S cathodes.

Constructing a Yolk–Shell Structure SiOx/C@C Composite for Long-Life Lithium-Ion Batteries

“…It can be found that the weightlessness ratio of SiO x /C, CS-SiO x /C@C, and YS-SiO x /C@C composites is 12, 23, and 24%, respectively. By comparison, the YS-SiO x /C@C composite has the highest relative carbon content, which also indicates that it has higher conductivity than the contrast samples …”

“…By comparison, the YS-SiO x / C@C composite has the highest relative carbon content, which also indicates that it has higher conductivity than the contrast samples. 38 To characterize the structural features of different samples, Raman spectroscopy was performed on SiO x /C, CS-SiO x /C@ C, and YS-SiO x /C@C composites. As shown in Figure 3c, all three samples have obvious characteristic peaks at 1360 and 1590 cm −1 , corresponding to different states of carbon materials, which represents the degree of defectivity (D band) and graphitization of carbon (G band).…”

Lithium‐Sulfur Batteries at Extreme Temperatures: Challenges, Strategies and Prospects

“…Once the temperature rises above sustainable limits of the thermal stable components, only fireextinguishing materials and intrinsic nonflammable electrolytes can ensure the safety of the battery. [64,65] Therefore, we classify the strategies for enhancing battery safety at high temperatures into the following two categories: 1) thermal stable materials to tolerate heat accumulation; 2) fireresistant materials and nonflammable electrolytes to suppress the battery combustion.…”

High-Tap-Density Sulfur Cathodes Made Beyond 400 °C for Lithium–Sulfur Cells with Balanced Gravimetric/Volumetric Energy Densities

“…1−3 On one hand, S 8 is inherently lightweight (2.07 g cm −3 ), 4 and often needs downsizing into the nanoscale for preferred redox kinetics; on the other hand, carbonaceous hosts have little tap density (0.1−0.3 g cm −3 ) due to their high porosity/specific surface areas (100−1500 m 2 g −1 ). 5 Second, the pasted cathode films often own low areal sulfur loading ratios (<5 mg cm −2 ), 6 as effected by not only the poor electronic conductivity of S 8 itself (∼5 × 10 −30 S cm −1 ) but also the lack of sulfur cathodedensified technologies. 7 Third, the electrolyte overconsumption in current LSB systems is inevitable since liquid solvents would fill in deep pores or other regions in carbon matrix, reducing E G in packed batteries.…”

“…First, compared to high tap density of commercial ternary-oxide (like NCM) cathode particles exceeding 2 g cm –3 , the low central value (∼1.2 g cm –3 ; Figure a) for developed S 8 /carbon cathodes, as induced by the following two aspects, goes against the fundamental prerequisite for compact electrode fabrication. − On one hand, S 8 is inherently lightweight (2.07 g cm –3 ), and often needs downsizing into the nanoscale for preferred redox kinetics; on the other hand, carbonaceous hosts have little tap density (0.1–0.3 g cm –3 ) due to their high porosity/specific surface areas (100–1500 m 2 g –1 ) . Second, the pasted cathode films often own low areal sulfur loading ratios (<5 mg cm –2 ), as effected by not only the poor electronic conductivity of S 8 itself (∼5 × 10 –30 S cm –1 ) but also the lack of sulfur cathode-densified technologies . Third, the electrolyte overconsumption in current LSB systems is inevitable since liquid solvents would fill in deep pores or other regions in carbon matrix, reducing E G in packed batteries. , Fourth, for larger pouch cells, kinetic constraints like S 8 volume expansions/poor utilization ratio, Li polysulfide (LiPS) shuttling, and sluggish Li 2 S n (2 < n < 6) phase transitions become aggravated, leading to the continual deterioration in LSBs performances. , …”