3D Net-like GO-d-Ti₃C₂T_x MXene Aerogels with Catalysis/Adsorption Dual Effects for High-Performance Lithium–Sulfur Batteries

Abstract

High theoretical specific capacity and rich resources in nature make sulfur an ideal cathode material for lithium–metal batteries. However, the shuttle effect and sluggish reduction reaction kinetics of lithium polysulfides (LiPSs) seriously affect the performance of the batteries. Here, we report GO-d-Ti3C2T x MXene aerogels with a novel three-dimensional (3D) reticular structure that served as sulfur host cathode materials for lithium–sulfur batteries (LiSBs), which benefits adsorption/catalytic conversion of LiPSs simultaneously. The dissolved LiPSs can be rapidly captured through chemisorption and then catalyzed into insoluble Li2S by low-coordinated-state Ti on the d-Ti3C2T x MXene surface. The combination of adsorption and catalysis enormously improves the capacity and cycling performance of LiSBs. At an S mass loading of 1.5 mg cm–2, the cell with the S@GM0.4 composite electrode achieves excellent cycling performance. The discharge specific capacity of 1039 mA h g–1 (1.56 mA h cm–2) decays to 542.9 mA h g–1 after 1000 cycles with a capacity fading rate of 0.048% per cycle at 0.5 C. Even at an S mass loading of 4.88 mg cm–2, an areal capacity of 4.3 mA h cm–2 can be achieved at 0.2 C.

Constructing MXene hydrogels and aerogels for rechargeable supercapacitors and batteries

“…50,60,71 When MXene hydrogels are prepared, the derived aerogels can be generated through the freeze-drying treatment of the MXene hydrogels. 26,72,73 Besides, MXene aerogels can also be fabricated through direct freeze-drying and thermal treatment of MXene colloidal solution. 74,75…”

“…Besides, Tang et al fabricated 3D net-like GO-d-Ti 3 C 2 T x MXene aerogels through hydrothermal reaction and freeze-drying. 26 The –COOH and –OH groups on GO could exchange with the surface-terminated functional groups of d-Ti 3 C 2 T x MXene, while GO could act as oxidation agents to oxidize the Ti atoms, forming a GO-d-Ti 3 C 2 T x MXene hydrogel. After freezing and drying the GO-d-Ti 3 C 2 T x MXene hydrogel, 3D net-like GO-d-Ti 3 C 2 T x MXene aerogels were generated.…”

“…3 Constructing MXene aerogels can inhibit the sheet restacking and effectively facilitate the overall electrochemical performance of Li–S batteries. 26,85,118 For example, Song et al synthesized a 3D porous Ti 3 C 2 T x MXene/rGO (MX/G) composite aerogel through hydrothermal reaction and freeze-drying and used this Ti 3 C 2 T x /rGO aerogel as the S host for the Li–S battery (Fig. 9a–c).…”

“…Besides, Ti 3 C 2 T x /rGO, Ti 3 C 2 T x /CNT, and Ti 3 C 2 T x /MnO 2 aerogels have been used as efficient S hosts for Li–S batteries with excellent electrochemical performances. 26,45,119,120…”

Sugarcane waste-derived activated carbon for lithium-sulfur batteries with enhanced performance by thiourea doping

“…Li-S batteries are notorious for poor cycling stability due to a phenomenon known as the shuttle effect. This is caused by the reduction of sulfur from S8 to Sn2 [4], which results in irreversible sulfur when the discharge voltage reaches 2.3 V [5]. As the voltage drops to 1.9 V, the lithium polysulfides, Li2S8, Li2S6, and Li2S4, are converted into insoluble Li2S2 and Li2S, resulting in corrosion at the negative electrode [6].…”