Electrochemical Reducation of TiO2/Al2O3/C to Ti3AlC2 and Its Derived Two-Dimensional (2D) Carbides

Ti3AlC2 has been directly synthesized from TiO2/Al2O3/C mixture precursors (3TiO2/0.5Al2O3/1.5C and 2TiO2/0.5Al2O3/C) by a molten salt electrolysis process at 900?C and 3.2 V in molten CaCl2. The influence of initial carbon content on the electrosynthesized products has been investigated. The result shows that the main phase of the electrosynthesized products changes from Ti3AlC to Ti2AlC and then to Ti3AlC2 with the increasing carbon content, and the electrosynthesized Ti3AlC2 is carbon deficient. The morphology observation shows that the electrosynthesized Ti3AlC2 particles possess smooth surfaces and dense flake-like microstructure. The reaction mechanism of the electroreduction of TiO2/Al2O3/C mixture precursor has been discussed based on the time- and position-dependent phase constitution analysis. In addition, two-dimensional (2D) Ti3AlC2-derived carbides, i.e., Ti3C2Tx and TiCx have been successfully prepared from the electrosynthesized Ti3AlC2 by a chemical etching process and an electrochemical etching process, respectively. Both derived carbides exhibit the similar layered structure, in which single layer carbides are composed of plentiful nanometer carbides. It is suggested that the molten salt electrolysis process has a great potential to be used for the facile synthesis of Mn+1AXn phases (such as Ti3AlC2) from their oxides precursors, and the synthesized Mn+1AXn phases can be further converted into 2D carbidesauthorsversionPeer reviewe

Honeycomb‐like carbon materials derived from coffee extract via a “salty” thermal treatment for high‐performance Li‐I2 batteries

Abstract Sustainable, conductive, and porous carbon materials are ideal for energy storage materials. In this study, honeycomb‐like carbon materials (HCM) are synthesized via a “salty” thermal treatment of abundant and sustainable coffee extract. Systematic materials characterization indicates that the as‐prepared HCM consists of heteroatoms (N and O, etc.) doped ultra‐thin carbon framework, possesses remarkable specific surface area, and excellent electrical conductivity. Such properties bestow HCM outstanding materials to be the blocking layer for Li‐I2 battery, significantly eliminating the dissolution of I2 in the cathode region and stopping the I2 from shutting to anode compartment. Furthermore, our electrochemical investigation suggests that HCM could incur surface pseudo‐capacitive iodine‐ions charge storage and contribute additional energy storage capacity. As a result, the resultant Li‐I2 battery achieves a robust and highly reversible capacity of 224.5 mAh·g−1 at the rate of 10 C. Even under a high rate of 50 C, the remarkable capacity of the as‐prepared Li‐I2 battery can still be maintained at 120.2 mAh·g−1 after 4000 cycles

Functional additives for solid polymer electrolytes in flexible and high-energy-density solid-state lithium-ion batteries

Solid polymer electrolytes (SPEs) have become increasingly attractive in solid-state lithium-ion batteries (SSLIBs) in recent years because of their inherent properties of flexibility, processability, and interfacial compatibility. However, the commercialization of SPEs remains challenging for flexible and high-energy-density LIBs. The incorporation of functional additives into SPEs could significantly improve the electrochemical and mechanical properties of SPEs and has created some historical milestones in boosting the development of SPEs. In this study, we review the roles of additives in SPEs, highlighting the working mechanisms and functionalities of the additives. The additives could afford significant advantages in boosting ionic conductivity, increasing ion transference number, improving high-voltage stability, enhancing mechanical strength, inhibiting lithium dendrite, and reducing flammability. Moreover, the application of functional additives in high-voltage cathodes, lithium–sulfur batteries, and flexible lithium-ion batteries is summarized. Finally, future research perspectives are proposed to overcome the unresolved technical hurdles and critical issues in additives of SPEs, such as facile fabrication process, interfacial compatibility, investigation of the working mechanism, and special functionalities.</p

Electrosynthesis of Ti3AIC2 from oxides/carbon precursor in molten calcium chloride

Layered micron-scale Ti3AlC2 powders have been successfully synthesized from TiO2/Al2O3/C precursor by a facile electrochemical process at 900 ?C and 3.1 V in molten CaCl2. Porous TiO2/Al2O3/C mixture pellet was served as the cathode and a graphite rod was employed as the anode. The influence of carbon content on the products was systematically investigated. The lattice parameters of the electrosynthesized Ti3AlC2 were determined. In addition, three reaction periods from TiO2/Al2O3/C to Ti3AlC2 including the generation of CaTiO3/Ca12Al14O33 intermediate compounds, the reduction of the oxides/compounds and the formation of Ti3AlC2 were investigated and confirmed. The results show that the electrochemical process is of great potential to the facile synthesis of Ti3AlC2, which may also have implication for the production of other Mn+1AXn phases from their inexpensive and abundantly available oxides precursorsPeer reviewe

Amylopectin from Glutinous Rice as a Sustainable Binder for High-Performance Silicon Anodes

Silicon (Si) has been investigated as a promising anode material because of its high theoretical capacity (4200 mAh g-1). However, silicon anode suffers from huge volume changes during repeated charge–discharge cycles. In this work, inspired by a remarkable success of the glutinous rice mortar in the Great Wall with ca. 2000-year history, amylopectin (AP), the key ingredient responsible for the strong bonding force, is extracted from glutinous rice and utilized as a flexible, aqueous, and resilient binder to address the most challenging drastic volume-expansion and pulverization issues of silicon anode. Additionally, the removal of toxic N-methyl-2-pyrrolidone (NMP) organic solvent makes the electrode fabrication process environmentally friendly and healthy. The as-prepared Si-AP electrode with 60 wt% of Si can uphold a high discharge capacity of 1517.9 mAh g−1 at a rate of 0.1 C after 100 cycles. The cycling stability of the Si-AP has been remarkably improved in comparison with both traditional polyvinylidene fluoride (PVDF) and aqueous carboxymethylcellulose (CMC) binders. Moreover, when the content of silicon in the Si-AP electrode increases to 70 wt%, a high discharge capacity of 1463.1 mAh g−1 can still be obtained after 50 cycles at 0.1° C. These preliminary results suggest that the sustainably available and environmentally benign amylopectin binders could be a promising choice for the construction of highly stable silicon anodes.</p

Sustainable Regeneration of Spent Graphite as a Cathode Material for a High-Performance Dual-Ion Battery

A resource-efficient and energy-saving recycling process is vital for establishing a sustainable circular economy of lithium-ion batteries (LIBs). Herein, we propose and use a one-step water-based recycling process to recycle and regenerate the graphite anode materials from spent LIBs. This process can not only successfully regenerate graphite from a solid electrolyte interface, dead lithium, and residual electrolyte and maintain its long-range-ordered layer graphite structure but also enlarge the interlayer distance and introduce abundant oxygen-containing functional groups to the as-regenerated graphite. Our electrochemical characterization and density functional theory (DFT) calculations reveal that expanded interlayer spacing and the oxygen-containing moieties make the regenerated graphite more suitable for storing PF6– rather than Li+. As such, the as-regenerated graphite facilitates resultant graphite dual-ion batteries (GDIBs) with impressive rate performance and stability, for example, an 85.3% capacity retention even after 500 cycles at 1 A g–1. Such a simple waste-to-resource strategy proposed in this work is expected to provide a low-cost and inspiring recycling pathway for spent LIBs and enable the sustainable manufacturing of GDIBs

Functional differentiation and genetic diversity of rice cation exchanger (CAX) genes and their potential use in rice improvement

Abstract Cation exchanger (CAX) genes play an important role in plant growth/development and response to biotic and abiotic stresses. Here, we tried to obtain important information on the functionalities and phenotypic effects of CAX gene family by systematic analyses of their expression patterns, genetic diversity (gene CDS haplotypes, structural variations, gene presence/absence variations) in 3010 rice genomes and nine parents of 496 Huanghuazhan introgression lines, the frequency shifts of the predominant gcHaps at these loci to artificial selection during modern breeding, and their association with tolerances to several abiotic stresses. Significant amounts of variation also exist in the cis-regulatory elements (CREs) of the OsCAX gene promoters in 50 high-quality rice genomes. The functional differentiation of OsCAX gene family were reflected primarily by their tissue and development specific expression patterns and in varied responses to different treatments, by unique sets of CREs in their promoters and their associations with specific agronomic traits/abiotic stress tolerances. Our results indicated that OsCAX1a and OsCAX2 as general signal transporters were in many processes of rice growth/development and responses to diverse environments, but they might be of less value in rice improvement. OsCAX1b, OsCAX1c, OsCAX3 and OsCAX4 was expected to be of potential value in rice improvement because of their associations with specific traits, responsiveness to specific abiotic stresses or phytohormones, and relatively high gcHap and CRE diversity. Our strategy was demonstrated to be highly efficient to obtain important genetic information on genes/alleles of specific gene family and can be used to systematically characterize the other rice gene families