Dual-Modified Electrospun Fiber Membrane as Separator with Excellent Safety Performance and High Operating Temperature for Lithium-Ion Batteries.

Polyacrylonitrile/Boric acid/Melamine/the delaminated BN nanosheets electrospun fiber membrane (PB3N1BN) with excellent mechanical property, high thermal stability, superior flame-retardant performance, and good wettability are fabricated by electrospinning PAN/DMF/H3BO3/C3H6N6/ the delaminated BN nanosheets (BNNSs) homogeneous viscous suspension and followed by a heating treatment. BNNSs are obtained by delaminating the bulk h-BN in isopropyl alcohol (IPA) with an assistance of Polyvinylpyrrolidone (PVP). Benefiting from the cross-linked pore structure and high-temperature stability of BNNSs, PB3N1BN electrospun fiber membrane delivers high thermal dimensional stability (almost no size contraction at 200 °C), excellent mechanical property (19.1 MPa), good electrolyte wettability (contact angle about 0°), and excellent flame retardancy (minimum total heat release of 3.2 MJ m-2). Moreover, the assembled LiFePO4/PB3N1BN/Li asymmetrical battery using LiFePO4 as the cathode and Li as the anode has a high capacity (169 mAh g-1 at 0.5 C), exceptional rate capability (129 mAh g-1 at 5 C), the prominent cycling stability without obvious decay after 400 cycles, and a good discharge capacity of 152 mAh g-1 at a high temperature of 80 °C. This work offers a new structural design strategy toward separators with excellent mechanical performance, good wettability, and high thermal stability for lithium-ion batteries.

Hydrothermal synthesis and adsorption behavior of H4Ti5O12 nanorods along [100] as lithium ion-sieves.

The adsorption method is a promising route to recover Li+ from waste lithium batteries and lithium-containing brines. To achieve this goal, it is vital to synthesize a stable and high adsorption capacity adsorbent. In this work, Li4Ti5O12 nanorods are prepared by two hydrothermal processes followed by a calcination process. Then the prepared Li4Ti5O12 nanorods are treated with different HCl concentrations to obtain a H4Ti5O12 adsorbent with 5 µm length along the [100] direction. The maximum amount of extracted lithium can reach 90% and the extracted titanium only 2.5%. The batch adsorption experiments indicate that the H4Ti5O12 nanorod maximum adsorption capacity can reach 23.20 mg g-1 in 24 mM LiCl solution. The adsorption isotherms and kinetics fit a Langmuir model and pseudo-second-order model, respectively. Meanwhile, the real adsorption selectivity experiments show that the maximum Li+ adsorption capacity reaches 1.99 mmol g-1, which is far higher than Mg2+ (0.03 mmol g-1) and Ca2+ (0.02 mmol g-1), implying these nanorods have higher adsorption selectivity for Li+ from Lagoco Salt Lake brine. The adsorption capacity for Li+ remains 91% after five cycles. With the help of XPS analyses, the adsorption mechanism of Li+ on the H4Ti5O12 nanorods is an ion exchange reaction. Therefore, this nanorod adsorbent has a potential application for Li+ recovery from aqueous lithium resources.