Porous and non-porous micrometer-sized glass platelets as separators for lithium-ion batteries

Novel Inorganic Membranes Based on Magnetite-Containing Silica Porous Glasses for Ultrafiltration: Structure and Sorption Properties

Porous glasses (PGs) obtained from sodium borosilicate (NBS) phase-separated glasses via leaching are promising inorganic membranes. Introducing Fe₂O₃ into NBS glasses imparts ferrimagnetic properties due to magnetite crystallization. Leaching of such glasses leads to the formation of magnetic PGs with interesting electro-surface characteristics. This work aimed to investigate the process of obtaining magnetite-containing PGs from NBS glasses depending on silica content, using XRPD and Raman spectroscopy, studying the PG membranes' structural characteristics and their sorption properties with respect to methylene blue (MB). Obtained PGs were characterized by a polymodal distribution of mesopores and a small number of micropores with specific surface area values of 32-135 m²/g and an average mesopore diameter of 5-41 nm. The kinetic data were analyzed using pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations. The equilibrium isotherms were fitted with Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. MB adsorption was found to be a complex process. The glass with the highest specific surface area demonstrated the maximum sorption capacity (10.5 mg/g). The pore size of PGs allowed them to be considered potential novel magnetic membranes for ultrafiltration.

A Review of Nonaqueous Electrolytes, Binders, and Separators for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are the most important electrochemical energy storage devices due to their high energy density, long cycle life, and low cost. During the past decades, many review papers outlining the advantages of state-of-the-art LIBs have been published, and extensive efforts have been devoted to improving their specific energy density and cycle life performance. These papers are primarily focused on the design and development of various advanced cathode and anode electrode materials, with less attention given to the other important components of the battery. The “nonelectroconductive” components are of equal importance to electrode active materials and can significantly affect the performance of LIBs. They could directly impact the capacity, safety, charging time, and cycle life of batteries and thus affect their commercial application. This review summarizes the recent progress in the development of nonaqueous electrolytes, binders, and separators for LIBs and discusses their impact on the battery performance. In addition, the challenges and perspectives for future development of LIBs are discussed, and new avenues for state-of-the-art LIBs to reach their full potential for a wide range of practical applications are outlined.

Graphic Abstract

The lithium ions storage behavior of heteroatom-mediated echinus-like porous carbon spheres: From co-doping to multi-atom doping

This study proposed a facile method to prepare echinus-like porous carbon spheres (PCS) with different heteroatom doping for lithium ions battery (LIBs). A metal-organophosphine framework (MOPF) was synthesized by employing riboflavin sodium phosphate as an organic ligand to conjugate with metal ions and then carbonized at mild temperature, leading to the formation of heteroatom doped PCS (H-PCS). As a result, (N, P) co-, (N, P, Ni) tri-, (N, P, Co) tri- and (N, Ni, Co, P) tetra-doped PCS were obtained to examine the insight into lithium-ion storage behavior of H-PCS. It was found that the specific surface area, pore texture and structural defects of H-PCS were dependent on doping of heteroatoms as well as the charge transfer resistance and Li-ion diffusion coefficient. Significantly, the redox reaction potential during the charge/discharge could be mediated upon the doping. Thus, when evaluated as anode for LIBs, the (N, Ni, Co, P) tetra-doped PCS exhibited highly reversible capacity of 680 mAh g^-1 at 0.1 A g^-1, excellent rate capability (115.9 mAh g^-1 at 1.0 A g^-1) and superior cycling performance (399.6 mAh g^-1 at 0.1 A g^-1). Moreover, the cyclic voltammogram measurements demonstrated that the doping of metal atoms was favorable for improving the capacitive contribution of surface limited diffusion. Thus, this work highlighted the importance of HCP with defined doping which could be considered as one of the prominent candidates for high-performance LIBs' anode.

Robust polyimide nanofibrous membrane with porous-layer-coated morphology by in situ self-bonding and micro-crosslinking for lithium-ion battery separator

Herein, we demonstrate a strategy to improve the tensile strength, thermal safety issues, and electrochemical performance of an as-synthesized polyimide separator. By spraying the solution of a specific chemical constituent on both sides of a poly(amic acid) non-woven membrane followed by thermal treatment, a novel polyimide nanofibrous membrane with porous-layer-coated morphology was successfully fabricated by in situ self-bonding and micro-crosslinking technique. The self-bonding and micro-crosslinking techniques improve the tensile strength of the nanofiber membranes from 5 MPa to 28 MPa by forming a crosslinked network structure, thereby reducing the risk of nanofiber disassembly during long-term operation. The rigid structure and aromatic groups in the polyimide chain enable the separator to have outstanding thermal dimensional stability at temperatures as high as 300 °C and thermal stability (5% weight loss at about 528 °C). Additionally, the unique flame retarding capability of polyimide ensures high security of the battery as well. Notably, the lithium-ion battery using porous-layer-coated polyimide separator exhibits a much higher capability (129.9 mA h g^-1, 5C) than that using a Celgard-2400 separator (95.2 mA h g^-1, 5C) and could work steadily at 120 °C, thus implying promising application in next generation high-safety and high-performance lithium-ion batteries.