Diana Golodnitsky

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes are attractive for sodium metal batteries but suffer from interfacial instability when coupled with layered oxide cathodes. Here, sodium β″-alumina (SBA) was tested as an ion-conducting filler in a PEO-based composite solid polymer electrolyte (CSPE) and as a major component of a composite cathode interlayer deposited via electrophoretic deposition using a polymeric ionic liquid (PIL). Although the solid polymer electrolyte without ceramic filler and the CSPE exhibited comparable ionic conductivity at 60 °C, the CSPE displayed lower activation energy and improved cell durability, underscoring the importance of ceramic reinforcement beyond bulk transport considerations. Within this stabilized CSPE platform, the SBA–PIL interlayer effectively regulated the cathode-electrolyte interface of layered Na0.7MnO2. As a result, polarization growth was suppressed, Coulombic efficiency increased (99.1% vs 97.9%), and capacity retention was significantly improved (76% vs 46% after 50 cycles) compared to pristine cathodes. Impedance analysis further revealed moderated charge-transfer resistance evolution and more stable interfacial kinetics. These findings demonstrate that combining ceramic-reinforced polymer electrolytes with targeted cathode interfacial engineering is an effective strategy to mitigate degradation in PEO-based sodium metal solid polymer batteries.

Fiber-based and fabric batteries signify a groundbreaking development in energy storage, allowing for the straightforward incorporation of power sources into wearable fabrics, intelligent apparel, and adaptable electronics. In this study, we introduce a novel strategy for one-step fabrication of a flexible lithium titanate oxide (Li₄Ti₅O₁₂, LTO) anode directly on a copper current collector via electrospinning, eliminating the need for high-temperature post-processing. Based on our previous work with electrospun nanofiber cathodes and carbon-based current collector, we prepared the LTO electrode using polyethylene oxide (PEO) as a binder and carbon additives to enhance mechanical integrity and conductivity. LTO fiber mats detached from the current collector were found to endure multiple instances of bending, twisting, and folding without any structural damage. LTO/Li cells incorporating electrospun fiber LTO electrodes with 72 wt% active material loading deliver a high capacity of 170 mAh g⁻¹ at 0.05 C. In addition, they demonstrate excellent cycling stability with a capacity loss of only 0.01% per cycle over 200 cycles and maintain a capacity of 160 mAh g⁻¹ at 0.1 C. The scalability of the heat-treatment-free method for fabricating flexible LTO anodes, together with the improved mechanical durability and electrochemical performance, offers a promising route toward the development of next-generation flexible and wearable energy storage devices.

Fast and easily scalable solvent-free extrusion of polymer electrolytes would represent significant progress in the development of environmentally friendly solid alkali-ion and alkali-metal batteries. In this study, we compare cast and extruded solid polymer electrolytes composed of lithium bis(trifluoromethanesulfonyl)imide salt of varying content dissolved in host matrix of polyurethane and polyethylene oxide. The electrolytes were characterized by means of differential scanning calorimetry, infrared spectroscopy, AC impedance, broad-band spectroscopy, and one-dimensional ⁷Li and ¹⁹F nuclear magnetic resonance. Analysis of the FTIR spectra showed that both polymers can coordinate lithium cations by ethylene oxide (EO) and amine (NH) electron donating groups. The interactions between Li⁺ and each polymer affect phase transition behavior, conductivity, and ion self-diffusion coefficients. Contrary to our expectations, it was found that unidirectional annealing, which was assumed to be induced by the extrusion process, does not alter out-of-plane ionic conductivity. Moreover, the bulk conductivity of extruded blended polymer electrolyte with 1:15 Li:EO ratio is more than twice that of its cast counterpart over the entire temperature range studied.

A composite film, composed of Li₆PS₅Cl ion-conducting nanoparticles and a polymerized ionic liquid binder, was electrophoretically deposited onto the LiNi_0.6Mn_0.2Co_0.2O₂ cathode surface, forming an artificial cathode electrolyte interphase.