[en] Fe-doped mesoporous anatase TiO_2/amorphous carbon composites (FC–TiO_2) are synthesized by a wet chemistry process. With Fe-doping concentration increasing, the microstructures of FC-TiO_2 change from prism to nanoparticle, and finally turns block structure. When used as anode materials for sodium ion batteries, the FC-TiO_2 electrodes exhibit a maximum capacity of 304 mA h g"−"1 at 0.1 A g"−"1 after 50 cycles with good rate capability (198 mA h g"−"1 at 2 A g"−"1). Three synergic effects can be attributed to the improved electrochemical performance of FC-TiO_2: (1) the high iron doping could largely narrow the band gap and restrain the growth of TiO_2 crystallite; (2) the carbon coating offers a beneficial conductivity environment; (3) the porous structure can shorten the electronic sodium ion pathway during cycling. Moreover, this synthesis method is very easy for mass production. Therefore, FC-TiO_2 should be an attractive and promising candidate for anode material of SIBs. - Graphical abstract: Fe-Doped Mesoporous Antanse TiO_2/Amorphous Carbon composites (FC–TiO_2) are synthesized using a wet chemistry process. Due to the existence of iron and carbon, as well as porous structure, the FC-TiO_2 electrodes exhibit high capacity and outstanding rate capability. - Highlights: "• Fe-doped antanse TiO_2/carbon composite is synthesized by a wet chemistry process. "• The composite possesses porous structure and improved conductivity. "• The obtained anodes delivers great cycle performance and rate-performance. "• The synthesis method is easy for large-lot production.

[en] Highlights: • Electrolyte based on fluorinated ether of ETFE is used in Li/S battery. • ETFE improves cycling, rate and self-discharging performances of Li/S battery. • Surface film on Li anode modified by ETFE inhibits the shuttle of polysulfides. - Abstract: Fluorinated ether of ethyl 1,1,2,2-tetrafluoroethyl ether (ETFE) was selected as electrolyte solvent for lithium/sulfur battery, and the influence of ETFE in electrolyte on cell properties was first investigated. The enhanced stability of electrolyte/anode interface and improved electrochemical performances (cycling, rate and self-discharging) of the Li/S cell are presented by using ETFE-containing electrolyte, especially for complete replacement of tetraethylene glycol dimethyl ether (TEGDME) by ETFE in combine with 1,3-dioxolane (DOL). It is found that ETFE plays a key role in modifying the surface composition and structure of the metallic Li, forming a strengthened protective film on the anode during cycling. Besides, ETFE is considered to decrease the dissolution of polysulfides in the electrolyte. These factors together restrict the contact and reaction between polysulfides and Li anode

[en] Cobalt–nitrogen-doped mesoporous carbon (Co–N–C) is synthesized as a host for lithium–sulfur batteries. With the Co–N–C composite as a sulfur host, the initial capacity of lithium–sulfur batteries is as high as 1290.8 mA h g⁻¹ at 0.2 C, and Li–S batteries still exhibit good cycling stability and high capacity with a retained capacity of 795.7 mA h g⁻¹ and a nearly 100% coulombic efficiency after 300 cycles. The good performance of Li–S batteries can be attributed to a higher specific surface area and pore volume of the carbon matrix and good chemical affinity of Co and N elements toward polysulfides. It is found that Co–N–C composite can effectively adsorb lithium polysulfide by physical, chemical adsorption and well inhibit the shuttle effect. In addition, Co–N–C composite which act as a catalyst can also significantly promote the conversion of polysulfide, accelerate the kinetics, thereby improving the performance of Li–S batteries.

[en] Highlights: • SP, MPC and G are integrated into hierarchically porous G/MPC/SP for sulfur cathode with high sulfur loading. • The sudden death of high-areal-capacity Li-S battery mainly originates from the accelerating Li dendrite growth. • The GF interlayer can reserve electrolyte to maintain stable local current density, inhibiting Li dendrite growth. With the considerable development in sulfur cathode, Li-S batteries have recently witnessed a significant improvement, especially in the gravimetric capacity and cycling performance. However, maintaining high energy density of Li-S batteries and their commercialization relies on the high areal loading and high utilization of active material on the electrode, which are always ignored in the most fundamental research reports. For the Li-S batteries with much higher sulfur loading, except for the well-known issues about polysulfide dissolution, some new issues such as electron and ion transport in thick cathode, depletion of electrolyte and lithium dendrite growth need to be addressed. Here, a Li-S battery with a high areal capacity is proposed by a systematic strategy incorporating two approaches as follows: 1) a hierarchically porous carbon host containing graphene (G), mesoporous carbon (MPC) and super P (SP) diminishes polysulfide migration and guarantees fast electron and ion transport in thick cathode; 2) a glass-fiber (GF) membrane severs as the electrolyte reservoir to prevent the short circuit resulted from the deficiency of liquid electrolyte. With these methods, the Li-S batteries with an ultrahigh sulfur loading of 13 mg cm⁻² provide a high areal capacity of 14.3 mA h cm⁻² (1099 mA h g⁻¹) at the first cycle and stable cycling performance with a reversible capacity of 628 mA h g⁻¹ (8.16 mA h cm⁻²) after 75 cycles at 0.1 C.

[en] Highlights: lThioacetamide is applied to the electrolyte of lithium-sulfur battery. lThioamides that contain primary-amine or secondary-amine groups are prone to generate recyclable materials. lThioacetamide boosts the solubility of Li₂S by intermolecular hydrogen bonds. lThe employment of thioacetamide promotes electrochemical performance of Li-S batteries. -- Abstract: Lithium-sulfur (Li-S) batteries with high theoretical specific capacity and ascendancy of raw materials are considered as a potential candidate for next-generation energy storage system. However, some intractable challenges, such as low sulfur utilization caused by the loss of active materials and surface passivation resulted from the deposition of insulating products, still hinder the practical application of lithium-sulfur batteries. Herein, various types of thioamides with different molecular structures are investigated as electrolyte additives to enhance the electrochemical performance of Li-S cells by adjusting the solubility of the final product, Li₂S. It is demonstrated that the thioamides that contain hydrogen in primary-amine or secondary-amine groups are prone to generate recyclable active materials. Specifically, thioacetamide (TAA) as an electrolyte additive not only provides extra reversible capacity, but also boosts the solubility of Li₂S by intermolecular hydrogen bonds, alleviating the passivation of the electrode and enhancing kinetics for the conversion of polysulfide to Li₂S. Therefore, the cells with TAA additive exhibit superior cycle performance and rate performance.