Simultaneous Immobilization and Conversion of Polysulfides on Co₃O₄–CoN Heterostructured Mediators toward High-Performance Lithium–Sulfur Batteries

Abstract

Lithium−sulfur batteries exhibit great promise as a next-generation rechargeable battery system due to their high energy density, natural abundance and nontoxicity. Nevertheless, the insulated property of sulfur and lithium sulfides, and the electrochemical instability of intermediate polysulfides obstruct the commercialization of Li-S technologies. Herein, a hetero-phase Co3O4-CoN sulfur host with the merits of efficient polysulfide anchoring (Co3O4) and high conductivity (CoN) is reported to enhance Li-S battery performance. Such porous Co3O4-CoN heterostructures endow the intermediated lithium polysulfides with highly-efficient immobilization-diffusionconversion process, thus enabling the accelerated redox kinetics and alleviating the polysulfide shuttling. The assembled cathode based on Co3O4-CoN/CC electrode exhibits a high initial capacity of 1225 mAh g -1 at 0.5C with excellent rate capability (887 mAh g -1 at 3C), and the specific capacity can be well-maintained to 627 mAh g -1 at 3C even after 500 cycles. Our work provides an in-depth insight into the rational design of comprehensive host materials which realizes synchronous LiPS adsorption and conversion, and will greatly promote the practical use of Li-S batteries.

Anion Design-Enabled High-Performance Cobalt-Based 3D Conductive Interlayers to Suppress the Shuttle Effect for Lithium–Sulfur Batteries

“…The decrease of Co 2p bonding energy indicates the strong chemical bond between LiPSs and CoS 2 (Figure S5a,b). The control sample (Figure S6b–d), Co 2p of Co 3 O 4 /CNFs, shows two peaks: Co 2p 3/2 (780.1 eV) and Co 2p 1/2 (795.9 eV), accompanied by two satellite peaks, which are 786.1 and 802.9 eV, respectively . The Co 2p of CoP/CNFs shows four peaks belonging to Co 2p 3/2 (779.2 and 782.1 eV) and Co 2p 1/2 (793.8 and 797.8 eV), respectively.…”

“…Moreover, the response current of the Co 3 O 4 /CNF electrode is lower than that of the CNF electrode during the redox process. It is caused by the poor electrical conductivity of Co 3 O 4 and the weak ability to promote LiPS conversion . However, the polarization voltage of Co–X compounds/CNF electrodes is lower than that of CNFs electrodes, indicating that the addition of Co–X compounds can increase the electrochemical reversibility during cycling.…”

Nanofibers Comprising Interconnected Chain‐Like Hollow N‐Doped C Nanocages as 3D Free‐Standing Cathodes for Li–S Batteries with Super‐High Sulfur Content and Lean Electrolyte/Sulfur Ratio

“…The tremendous advances in Li-S batteries (LSBs) during the last decade have brought them to the forefront of several rechargeable battery technologies. [1][2][3][4][5][6][7][8][9][10] However, the commercialization of LSBs is still lagging compared to their counterparts owing to several fundamental drawbacks such as the highly insulating nature of sulfur and its discharge product, i.e., Li 2 S formation and migration of lithium polysulfide (LiPS) species, which results in the loss of active material, severe carbonization and employed it as the LSB cathode substrate. [28] Similarly, Guo et al synthesized and tested N-CNF electrodes for Li-LiPSs battery performance.…”

“…The tremendous advances in Li–S batteries (LSBs) during the last decade have brought them to the forefront of several rechargeable battery technologies. [ 1–10 ] However, the commercialization of LSBs is still lagging compared to their counterparts owing to several fundamental drawbacks such as the highly insulating nature of sulfur and its discharge product, i.e., Li 2 S formation and migration of lithium polysulfide (LiPS) species, which results in the loss of active material, severe volume changes during charge–discharge, and poor cycling stability accompanied by low Coulombic efficiencies. [ 11–17 ] In addition, highly impractical cell parameters, such as low effective sulfur content in the electrode (<70 wt%), low sulfur loading (<2 mg cm –2 ), and high electrolyte/sulfur (E/S) ratio (>10 µL mg –1 ) generally result in overrated electrochemical performance such as high initial discharge capacities approaching the theoretical value, exceptional rate capabilities, and outstanding cycling stabilities.…”

Engineering a TiNb2O7-Based Electrocatalyst on a Flexible Self-Supporting Sulfur Cathode for Promoting Li-S Battery Performance

“…Thereinto, the metal oxides with connatural limitation and a unique band structure furnish plentiful polar active sites for adsorbing LiPSs . Peculiarly, some single transitional metal oxides have been introduced into Li-S batteries to catalyze the conversion reaction of LiPSs, including Ti 2 O 3 , Co 3 O 4 , VO 2 , MoO 2 , TiO 2 , Nb 2 O 5 , etc. However, due to the low conductivity and limited catalytic capacity of single transition metal oxides, the improvement of electrochemical performance is still limited.…”