Lithium-Ion-Sieve-Embedded Hybrid Membranes for Anion-Exchange- and Cation-Concentration-Driven Li/Mg Separation.

There is an urgent need to develop efficient and environmentally friendly technologies for separating Li+ from brines containing abundant Mg2+ to meet the growing demand for lithium resources. In this work, we prepared hybrid membranes by integrating hydrogen manganese oxide (HMO), a lithium-ion sieve, as a filler into anion-exchange membranes (AEMs), the quaternary ammonium-functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO) and poly(m-terphenyl piperidinium) (m-PTP). Cations are transported by electrostatic attraction originating from anions and the concentration difference across membranes. Because of the effects of electrostatic repulsion of the fixed cationic groups and steric resistance in AEMs, Li+ with less charge and smaller radius will preferentially pass through the membrane. In addition, the presence of HMO provides an additional fast transport channel for Li+, resulting in an enhanced Li+/Mg2+ separation performance. The results show that 20%HMO@m-PTP exhibits high Li+ flux (0.48 mol/m2·h) and Li+/Mg2+ selectivity (ßLi+/Mg2+ = 14.1). Molecular dynamics simulations show that m-PTP has more free volume than QPPO, which is beneficial for rapid cation transport. Spectral analysis confirms the insertion and sieving of Li+ in HMO. This work illustrates the great potential of anion-exchange- and cation-concentration-driven hybrid membranes based on lithium-ion sieves for low-energy and efficient Li+ extraction processes.

Aqueous Dual-Electrolyte Full-Cell System for Improving Energy Density of Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are regarded as one of the most promising candidates for next-generation energy storage devices and have been gradually grasping market share for their low cost and similar reaction mechanism and production process as compared to lithium-ion batteries. However, the low energy density of SIBs restricts their practical applications. For example, regular full cells of a Prussian blue cathode and NASICON anode have only a low discharge capacity (about 77 mA h/g at 1 C). Taking into account the compatibility of the electrolyte and electrode materials, a novel strategy for a viable aqueous dual-electrolyte sodium-ion battery (ADESIB) has been proposed using Na2SO4 solution as the anolyte and redox-active sodium hexacyanoferrate Na4Fe(CN)6 solution as the catholyte to accommodate a NASICON NaTi2(PO4)3 anode and Prussian blue Na2NiFe(CN)6 cathode. The capacity of Na+ ion deinsertion/insertion electrodes combined with the redox chemistry of the Na4Fe(CN)6 catholyte thus enhances overall charge storage and energy density. The ADESIB delivers a capacity of about 113 mA h/g at 1 C, showing a 43% improvement over batteries with a regular single Na2SO4 electrolyte. Additionally, the dual-electrolyte full-cell system is proved to reach a 84.7% capacity retention after 1000 cycles, mainly due to the synergy of the electrolytes in both sides. This pioneering research proposes an aqueous dual-electrolyte sodium-ion full cell, showing potential applications in a new sodium-ion full battery system.

Structure Recovery and Recycling of Used LiCoO2 Cathode Material.

A large number of lithium batteries have been retiring from the market of energy storage. Thus, recycling of the used electrode materials is becoming urgent. In this study, an industrial machinery processing was used to recover the crystal structure of the waste LiCoO2 materials with the combination of small-scale equipment repair technology. The results show that the crystal parameters of the repaired LiCoO2 material become small, the unit cell volume is reduced, and the crystal structure tends to be stable. The Co-O bond length of 1.9134 nm, O-Co-O bond angle of 94.72°, the (003) interplanar spacing of 0.467 nm indicate the excellent recovery level of the repaired LiCoO2 . In addition, the electrochemical performance of the repaired LiCoO2 material is greatly improved, compared with the waste material. The capacity of the repaired electrode material can be maintained at 120 mAh g-1 after 100 cycles at the current density of 0.2C. The promising rate performance of the repaired electrode material demonstrates the stable structure. This research work provides a large-scale method for the direct recovery of LiCoO2 with the reduction of unnecessary energy and reagent consumption, which will be beneficial to the environmental protection.

Total synthesis of phorboxazole B.

An efficient and highly convergent total synthesis of the potent antitumor agent phorboxazole B has been achieved. The synthetic strategy of this synthesis features: 1) a highly efficient substrate-controlled hydrogenation to construct the functionalized cis-tetrahydropyrane unit; 2) iterative crotyl addition to synthesize the segment that contains alternating hydroxyl and methyl substituents; 3) Hg(OAc)2/I2-induced cyclization to establish the cis-tetrahydropyrane moiety; 4) 1,3-asymmetric induction in the Mukaiyama aldol reaction to afford the stereogenic centers at C9 and C3; and 5) the exploration of the Still-Gennari olefination reaction to complete the macrolide ring of phorboxazoloe B.

Toward the total synthesis of phorboxazole B: an efficient synthesis of the C20-C46 segment.

An efficient synthesis of the C20-C46 segment of phorboxazole B is described. The key steps involved Hg(OAc)(2)/I(2)-induced cyclization to construct the cis-tetrahydropyran moiety, the coupling of the metalated 2-methyloxazole 7 with lactone 6, and Julia olefination to furnish the conjugated diene moiety.

Toward the total synthesis of natural peloruside a: stereoselective synthesis of the backbone of the core.

[reaction: see text] An asymmetric synthesis of the backbone of the core of natural peloruside A is described. Key elements include reiterative application of enantioselective allylation to establish the stereochemistry of the backbone and a double asymmetric aldol reaction to successfully couple two fragments.

A concise and stereoselective synthesis of squalamine.

[reaction: see text] A short and highly stereoselective synthesis of the novel steroid squalamine (1) was accomplished in nine steps from easily available methyl chenodeoxylcholanate 2. Our synthesis featured improved dehydrogenation of 4 followed by conjugate reduction to construct the trans AB-ring system and efficient asymmetric isopropylation of aldehyde 6 to introduce the C-24R-hydroxyl group.