In-situ polymerized composite polymer electrolyte with cesium-ion additive enables dual-interfacial compatibility in all-solid-state lithium-metal batteries.

Solid composite polymer electrolytes (CPEs) that combine the advantages of inorganic and organic electrolytes are regarded as the most appealing candidates for all-solid-state lithium-metal batteries (ASSLMBs). Nonetheless, the interfacial incompatibility issues resulting from poor cathode/electrolyte contact and uncontrolled dendrite growth on Li anode are fundamentally challenging for the development of ASSLMBs. Herein, we design a solid CPE with dual-interface compatibility based on in-situ thermal polymerization of a precursor solution containing polymer monomer, cesium-ion (Cs+), and inorganic Li+ conductor. The resultant Cs+ containing CPE creates intimate interface contact with the cathode while achieving high interfacial stability with the Li-metal anode. Accordingly, this solid electrolyte can perform reversible Li plating/stripping over 750 h at 0.3 mA cm-2 and a critical current density (CCD) of 0.8 mA cm-2, in sharp contrast with its Cs+-free counterpart (failure after 11 h and a CCD of 0.5 mA cm-2). Furthermore, the full ASSLMBs (Li|LiFePO4) enable decent capacity retention of 90% over 100 cycles at 0.5C and high Coulombic efficiency of nearly 100%. Therefore, constructing solid-state electrolytes with dual-interfacial compatibility may be an effective avenue to achieve high-performance ASSLMBs.

3D Coral-like LLZO/PVDF Composite Electrolytes with Enhanced Ionic Conductivity and Mechanical Flexibility for Solid-State Lithium Batteries.

Composite polymer electrolytes (CPEs) are very promising for high-energy lithium-metal batteries as they combine the advantages of polymeric and ceramic electrolytes. The dimensions and morphologies of active ceramic fillers play critical roles in determining the electrochemical and mechanical performances of CPEs. Herein, a coral-like LLZO (Li6.4La3Zr2Al0.2O12) is designed and used as a 3D active nanofiller in a poly(vinylidene difluoride) polymer matrix. Building 3D interconnected frameworks endows the as-made CPE membranes with an enhanced ionic conductivity (1.51 × 10-4 S cm-1) at room temperature and an enlarged tensile strength up to 5.9 MPa. As a consequence, the flexible 3D-architectured CPE enables a steady lithium plating/stripping cycling over 200 h without a short circuit. Moreover, the assembled solid-state Li|LiFePO4 cells using the electrolyte exhibit decent cycling performance (95.2% capacity retention after 200 cycles at 1 C) and excellent rate capability (120 mA h g-1 at 3 C). These results demonstrate the superiority of 3D interconnected garnet frameworks in developing CPEs with excellent electrochemical and mechanical properties.

Self-assembled N-doped carbon with a tube-in-tube nanostructure for lithium-sulfur batteries.

Lithium-sulfur batteries hold broad prospects as the low-cost and high-energy storage system. However, the practical application is limited by the intrinsic insulating nature of sulfur and severe shuttle effect of soluble polysulfide intermediates. Herein, we demonstrate a convenient self-assembly strategy for encapsulating carbon nanotubes in nitrogen-doped hollow carbon shells, to construct a nitrogen-doped tube-in-tube carbon nanostructure (NTTC) as a host material of sulfur. In this peculiar structure, the highly conductive carbon nanotube cores facilitate the electron transfer while the hollow porous structure is capable of accommodating high sulfur content of 70 wt% in the composites. Moreover, the nitrogen doping helps to alleviate the shuttle effect owing to enhanced chemisorption towards polysulfides. Benefiting from these merits, the NTTC/S composite with the high areal mass loading of ~2.5 mg cm-2 presents a high reversible capacity (1346.9 mAh g-1 at 0.05 C) and excellent rate capability (533.5 mAh g-1 at 3C). More impressively, NTTC/S electrode exhibits good cycling stability at a high rate of 2 C corresponding to slight capacity decay of 0.055% per cycle over 500 discharge/charge cycles.

Stereoselective Synthesis of Homofarnesenes: Establishment of an Efficient Method for the Stereoselective Preparation of Acyclic Tetrasubstituted Olefins.

A new method for the stereoselective synthesis of tetrasubstituted olefins is described. ß-Ketophosphonates are alkylated via conventional methods, and a Grignard reagent is used to diastereoselectively add to the carbonyl group of the resulting intermediates. The elimination of hydroxyl phosphonates yielded the desired tetrasubstituted olefins in a stereoselective manner. Thus, homofarnesenes of fire ant trail pheromones have been synthesized efficiently using this strategy.

Advanced Separators for Lithium-Ion and Lithium-Sulfur Batteries: A Review of Recent Progress.

Li-ion and Li-S batteries find enormous applications in different fields, such as electric vehicles and portable electronics. A separator is an indispensable part of the battery design, which functions as a physical barrier for the electrode as well as an electrolyte reservoir for ionic transport. The properties of the separators directly influence the performance of the batteries. Traditional polyolefin separators showed low thermal stability, poor wettability toward the electrolyte, and inadequate barrier properties to polysulfides. To improve the performance and durability of Li-ion and Li-S batteries, development of advanced separators is required. In this review, we summarize recent progress on the fabrication and application of novel separators, including the functionalized polyolefin separator, polymeric separator, and ceramic separator, for Li-ion and Li-S batteries. The characteristics, advantages, and limitations of these separators are discussed. A brief outlook for the future directions of the research in the separators is also provided.