Utilizing an Oxygen-Rich Interface by Hydroxyapatite to Regulate the Linear Diffusion for the Stable Solid-State Electrolytes

Z-Type Interstice Leap Migration Driving High Ionic Conductivity in Monoclinic LiBiBr4 Solid State Electrolyte

Halide solid electrolytes receive much attention due to their electrochemical properties, such as high ionic conductivity, oxidative stability, and ease of preparation. In this work, a bromide solid electrolyte LiBiBr4, exhibiting ease of processing and high ionic conductivity, is designed for the first time and investigated through a comparative investigation with monoclinic LiAlCl4 and LiAlBr4 for the migration path. The processing pressure for LiBiBr4 with annealing at 120 °C is less than one-tenth that of other chloride electrolytes (≈5 MPa). Computational analyses unveil crucial mechanistic insights into the three migration mechanisms and the factors that influence them within the monoclinic structure. The distribution and distance of non-Li polyhedrons to the migration pathways are pivotal for the migration. The strategic positioning of the Bi polyhedron in LiBiBr4 is far from the Li+ pathway. The unique leap migration within the LiBiBr4 has a lower energy barrier and facilitates an interconnected migration that forms a 3D interstice network. This interconnected leap migration network within LiBiBr4 constitutes a Z-type interstice leap migration along the ab-axis. Thus, the LiBiBr4 obtains a high ionic conductivity of 0.19 mS cm-1 with the 0.349 eV low activation energy. This discovery and research methods provide significant impetus and support for the development of halogen-based electrolytes.

Upgrading Gel Electrolytes Through Electrostatic-Induced Dual-Salt Paradigm for Superior Zn-Ion Battery Performance

Gel electrolytes are gaining attention for rechargeable Zn-ion batteries because of their high safety, high flexibility, and excellent comprehensive electrochemical performances. However, current gel electrolytes still perform at mediocre levels due to incomplete Zn salts dissociation and side reactions. Herein, an electrostatic-induced dual-salt strategy is proposed to upgrade gel electrolytes to tackle intrinsic issues of Zn metal anodes. The competitive coordination mechanism driven by electrostatic repulsion and steric hindrance of dual anions promotes zinc salt dissociation at low lithium salt addition levels, improving ion transport and mechanical properties of gel electrolytes. Li+ ions and gel components coordinate with H2O, reducing active H2O molecules and inhibiting associated side reactions. The dual-salt gel electrolyte enables excellent reversibility of Zn anodes at both room and low temperatures. Zn||Polyaniline cells using the dual-salt gel electrolyte exhibit a high discharge capacity of 180 mAh g-1 and long-term cycling stability over 180 cycles at -20 °C. The dual-salt strategy offers a cost-effective approach to improving gel electrolytes for high-performance flexible Zn-ion batteries.

Spontaneous Desaturation of the Solvation Sheath for High-Performance Anti-Freezing Zinc-Ion Gel-Electrolyte

In recent years, gel-electrolyte becomes pivotal in preventing hydrogen evolution, reducing dendrite growth, and protecting the zinc metal anode for zinc-ion batteries. Herein, a polyvinyl alcohol-based water-organic hybrid gel electrolyte with Agar and dimethyl sulfoxide is designed to construct the spontaneous desaturation of the solvation sheath for reducing hydrogen evolution and dendrite growth at room temperature and even low temperature. According to experimental characterization and theoretical calculations, the well binding between multihydroxy polymer and H2 O is achieved in the hybrid desaturated gel-electrolyte to regulate the inner and outer sheath. The ionic conductivity of hybrid gel-electrolyte reaches 7.4 mS cm-1 even at -20 °C with only 0.5 m zinc trifluoromethanesulfonate (Zn(OTf)2 ). The Zn symmetric cells cycle over 1200 h under 26 and -20 °C with improved mechanical properties and electrochemical performance. The asymmetric Zn || Cu cell with hybrid gel electrolyte reaches ≈99.02% efficiency after 250 cycles. The capacity of full cell is maintained at around 74 mAh g-1 with almost unchanged retention rate from 50 to 300 cycles at -20 °C. This work provides an effective strategy for desaturated solvation to reach anti-freezing and high-density Zn energy storage devices.