Eliminating Hydrogen Fluoride through Piperidine-Doped Separators for Stable Li Metal Batteries with Nickel-Rich Cathodes

Hydrofluoric acid (HF)-induced electrode and interfacial structure degeneration poses a significant challenge for high-voltage lithium metal batteries (LMBs). To address this issue, we propose a separator strategy that involves decorating a regular polyethylene (PE) separator with molecular sieves (TW) impregnated with piperidine (PI). The porous structure of the TW serves as a reaction chamber for PI and HF. As a result, the HF content in the controlled electrolyte with 500 ppm H2O (ELE-500) is notably reduced when using TW@PI-PE separators, thereby shielding nickel-rich cathodes from HF etching. Simultaneously, due to the hydrolysis of Li salts, and the inertness of PI towards H2O, a uniform lithium fluoride (LiF)-rich solid electrolyte interphase can form on the Li metal anode, further mitigating dendrite formation. The lifespan of the symmetric Li cell using the TW@PI-PE separator is doubled in ELE-500, exhibiting stable 500-hour cycles at 3 mA cm-2 and 3 mAh cm-2. Additionally, with the effective limitation of transition metal (TM) dissolution, the 4.6-V LMBs employing a LiNi0.8Co0.1Mn0.1O2 cathode maintain an 81 % capacity retention over 100 cycles, even in ELE-1000. The innovative TW@PI system presented here offers a fresh perspective for future research aimed at eliminating HF in LMBs.

Al-Modified Ti-MOR as a robust catalyst for cyclohexanone ammoximation with enhanced anti-corrosion performance

The skeleton desilication accompanied by Ti active sites leaching accounts for the dominant chemical deactivation reasons in the alkali liquid-phase ammoximation, which could be retarded by creating a protective Al-rich shell.

Farringtonite as an efficient catalyst for linear-chain α-olefin epoxidation with aqueous hydrogen peroxide

A convenient, scalable, benign, and efficient epoxidation method based on farringtonite, without the use of transition metals, was developed for the first time.

Selective synthesis of epichlorohydrin via liquid-phase allyl chloride epoxidation over a modified Ti-MWW zeolite in a continuous slurry bed reactor

The epoxidation of allyl chloride (ALC) to epichlorohydrin (ECH) with H₂O₂ using a piperidine (PI)-modified Ti-MWW catalyst (Ti-MWW-PI) in a continuous slurry reactor was investigated to develop an efficient reaction system for the corresponding industrial process.

Modified Ti-MWW Zeolite as a Highly Efficient Catalyst for the Cyclopentene Epoxidation Reaction

The liquid-phase epoxidation of cyclopentene (CPE) was performed in the Ti-zeolite/H₂O₂ catalytic system for the clean synthesis of cyclopentene oxide. Among all the Ti-zeolites (Ti-Beta, Ti-MOR, Ti-MCM-68, TS-1, TS-2, and Ti-MWW) investigated in the present study, Ti-MWW provided relatively lower CPE conversion of 13% due to the diffusion constrains but a higher CPO selectivity of 99.5%. The catalytic performance of Ti-MWW was significantly enhanced by piperidine (PI) treatment, with the CPE conversion and CPO selectivity increased to 97.8 and 99.9%, respectively. The structural rearrangement upon PI treatment converted the 3-dimensional (3D) MWW structure to a 2D lamellar one, which enlarged the interlayer space and greatly alleviated the diffusion constrains of cyclic cyclopentene. Furthermore, the newly constructed “open site” six-coordinated Ti active sites with PI as the ligand exhibited higher catalytic activity. The two factors contributed to more significant enhancement of the activity upon PI-assisted structural arrangement compared to the cases in linear alkenes.