New Class Of Solid Electrolytes Research Articles

Garnet-Type Zinc Hexacyanoferrates as Lithium, Sodium, and Potassium Solid Electrolytes

Sodium-ion batteries offer an attractive alternative to lithium-based chemistries due to the lower cost and abundance of sodium compared to lithium. Using solid electrolytes instead of liquid ones in such batteries may help improve safety and energy density, but they need to combine easy processing with high stability toward the electrodes. Herein, we describe a new class of solid electrolytes that are accessible by room-temperature, aqueous synthesis. The materials exhibit a garnet-type zinc hexacyanoferrate framework with large diffusion channels for alkaline ions. Specifically, they show superionic behavior and allow for facile processing into pellets. We compare the structure, stability, and transport properties of lithium-, sodium-, and potassium-containing zinc hexacyanoferrates and find that Na2Zn3[Fe(CN)6]2 achieves the highest ionic conductivity of up to 0.21 mS/cm at room temperature. In addition, the electrochemical performance and stability of the latter solid electrolyte are examined in solid-state sodium-ion batteries.

Unveiling the dynamic change in the ionic conductivity of a solid-state binary mixture comprising an organic ionic plastic crystal and LiBF4

The binary composites of organic ionic plastic crystals (OIPCs) and lithium salts are a promising new class of solid electrolytes for all-solid-state batteries (ASSBs). One of the primary areas of research to enable their application into battery devices is to understand their complex physicochemical features, in particular their phase behaviors in response to changing compositions and the ensuing correlation with ionic conductivities. Herein, the phase behaviors and transport properties of binary OIPC–lithium-salt composites are reported over the full compositional window using N-ethyl-N-methylpyrrolidinium tetrafluoroborate ([C2mpyr][BF4]) and lithium tetrafluoroborate (LiBF4). The phase diagram of the Lix[C2mpyr]1–x[BF4] electrolyte was constructed and used to not only provide valuable insights into the key composition–property relationships but also guide the selection of Li+ concentrations in OIPC composites for Li+-based ASSBs. Differential scanning calorimetry and 19F nuclear magnetic resonance (NMR) spectroscopy revealed the emergence of intermediate secondary phases as the composition was varied. Significant and sudden variations in ionic conductivity at or near the Li+-concentration-driven phase transitions were attributed to the presence of these intermediate phases which ultimately provide the dominant contribution to the ionic conductivity of the Lix[C2mpyr]1–x[BF4] electrolyte.

Front Cover image

The cover image focuses on a new class of solid electrolytes termed frameworked electrolytes, where the “macroscopically solid” frameworks are purposely laden with 3D ionic channels in the sub‐nano scales, giving rise to both a high ionic conductivity and a desirable interface with the electrode solids. The authors demonstrate a zeolite framework structure based frameworked electrolyte with superior ion diffusion kinetics, which ensures the design of high‐performance all solid state battery running at room temperature. It is confident that the emergence of frameworked electrolyte serves as a powerful motivator for embarking on a new expedition to design the next‐generation battery for EVs or portable electronics in the future. image

Compositionally complex perovskite oxides: Discovering a new class of solid electrolytes with interface-enabled conductivity improvements

Compositionally complex perovskite oxides: Discovering a new class of solid electrolytes with interface-enabled conductivity improvements

Stabilizing the Halide Solid Electrolyte to Lithium by a β-Li3N Interfacial Layer.

As a new class of solid electrolytes, halide solid electrolytes have the advantages of high ionic conductivity at room temperature, stability to high-voltage cathodes, and good deformability, but they generally show a problem of being unstable to a lithium anode. Here, we report the use of Li3N as an interface modification layer to improve the interfacial stability of Li2ZrCl6 to the Li anode. We found that commercial Li3N can be easily transformed into an α-phase and a β-phase by ball-milling and annealing, respectively, in which β-phase Li3N simultaneously has high room-temperature ionic conductivity and good stability to both Li and Li2ZrCl6, making it a good choice for an artificial interface layer material. After the modification of the β-Li3N interfacial layer, the interfacial impedance between Li2ZrCl6 and the Li anode decreased from 1929 to ∼400 Ω. At a current density of 0.1 mA cm-2, the overpotential of the Li symmetric cell decreased from 250 to ∼50 mV, which did not show an obvious increase for at least 300 h, indicating that the β-Li3N interface layer effectively improves the interfacial stability between Li2ZrCl6 and Li.

Protic Ionic Liquids‐Based Crosslinked Polymer Electrolytes: A New Class of Solid Electrolytes for Energy Storage Devices

Protic Ionic Liquids‐Based Crosslinked Polymer Electrolytes: A New Class of Solid Electrolytes for Energy Storage Devices

Protic Ionic Liquids‐Based Crosslinked Polymer Electrolytes: A New Class of Solid Electrolytes for Energy Storage Devices

Herein, the preparation of an innovative crosslinked polymer electrolyte (PEO_HPyr) encompassing protic ionic liquids (PILs) displaying high ionic conductivity, wide thermal, and electrochemical stability is reported, thus suitable for use in safe energy storage devices. The first example of an all‐solid‐state electrochemical double layer capacitor (EDLC) containing a PEO_HPyr‐based electrolyte is presented, which shows high performance at ambient temperature and exceptional stability. Furthermore, the first example of a PIL‐based lab‐scale lithium‐metal cell with lithium iron phosphate cathodes is also presented, which provides almost full capacity (i.e., 150 mAh g−1 at C/20) and highly reversible cycling at ambient conditions and different current rates. The excellent results obtained clearly demonstrate that PIL‐based crosslinked polymer electrolytes represent a new and very interesting class of solid electrolytes for energy storage devices.

Ionic conduction in Li3Na(NH2)4: Study of the material design for the enhancement of ion conductivity in double-cation complex hydrides

Complex hydrides have collected recent attention as a new class of solid electrolytes with potential applications in all-solid-state batteries. To improve ionic conduction in the complex hydrides, multi-cation crystal structure can be attractive. It will allow tuning the cation dynamics via structure modification depending on types and number of additional cations. However, multi-cation crystal structure struggles with the inter-cation scattering among different cations. To address this issue, understanding the conduction mechanisms in the multi-cationic crystals is indispensable. Here, we study cationic conduction in a double-cation (Li and Na) complex hydride Li3Na(NH2)4, which is formed by replacing Li (with Na) from specific lattice site of LiNH2 without altering the crystal symmetry. The nuclear magnetic resonance (NMR) measurements found that Li3Na(NH2)4 is a Li-ion conductor with negligibly small Na-ion conduction. This finding is critically important to elucidate Li-ion conduction mechanism in Li3Na(NH2)4. Enhanced Li-ion conduction in Li3Na(NH2)4 is achieved by (a) suppressing diffusion of Na cation trapped at the strategically located 2c lattice sites under deep potential well; and (b) by increasing the Li defect concentration influenced by the larger volume of the Li metastable sites due to Na substitution into LiNH2. Our study will provide the design principle for multi-cation complex hydrides, and accelerate development of superior solid electrolytes for all-solid-state batteries.

“Liquid-in-Solid” and “Solid-in-Liquid” Electrolytes with High Rate Capacity and Long Cycling Life for Lithium-Ion Batteries

Herein we present a new class of ionogel electrolyte for lithium-ion batteries, which can be prepared in either “liquid-in-solid” or “solid-in-liquid” form. The electrolytes are prepared by a nonaqueous self-assembly sol–gel process, in which ionic liquid electrolyte is immobilized within an inorganic gel. These electrolytes were found to exhibit high ionic conductivity, low electronic conductivity, and good thermal and mechanical stability. The inorganic gels weaken the interaction of anions and cations and thereby improve lithium salt dissociation and enhance transport of Li+. Also, the electrolytes are stable: no spontaneous phase separation occurs after 1 year of storage. In addition, their synthesis and shaping are very easy and cheap and form a new class of solid electrolytes, which offer exciting opportunities for preparation of in situ solid-state lithium-ion batteries. Cells with LiFePO4 cathodes and ionogel electrolyte attained a capacity of 150 mAh/g for more than 300 cycles, and even at the 2C...

XAFS study of BaCe 1−xTi xO 3 and Ba 1−yCe 1−xY xO 3 protonic solid electrolytes

The paper reports on the doping-influenced evolution of the local structure in a new class of solid electrolytes, BaCe 1− x Ti x O 3 and Ba 1− y Ce 1− x Y x O 3 perovskites, to be used in intermediate temperature fuel cells. The local environments of the Ti, Y and Ce cations were studied by means of X-ray absorption spectroscopy. The Ti XAFS spectra reveal a decrease of the local symmetry of titanium site with increasing doping. The Ce and Y EXAFS functions show a larger amount of oxygen vacancies created by Y doping than that caused by barium understoichiometry.

Solid Oxide Fuel Cell Employing a New Class of Solid Electrolytes, La9.33+x(Si6-yAly)O26+1.5x-0.5y

Dense and high oxide ion conducting solid electrolytes, Al-doped lanthanum silicate [La9.33+x(Si6−yAly)O26+1.5x−0.5y] were fabricated and their electrical conducting properties were studied. Among the specimens tested, the electrical conductivity of the slight Al-doped one (x=0.67, y=0.2) was the highest though that was the weighed composition. Its conductivity was almost P(O2)-independent, while a slight increase in conductivity with increasing P(O2) was observed in the high temperature region. The current-voltage characteristic of a fuel cell utilizing the novel electrolytes was also investigated employing platinum electrodes as both anode and cathode.

Anode Composites Based on NiO and Apatite-Type Lanthanum Silicate for Intermediate Temperature Solid Oxide Fuel Cells

AbstractComposite materials based on NiO and doped apatite-type lanthanum silicates (ATLS) that are new class of solid electrolytes were studied as anode materials for intermediate temperature solid oxide fuel cells (IT SOFC), with possibility to use both H2 and CH4 as a fuel being payed attention to. For cermets preparation different methods of Ni addition such as incipient wetness impregnation, modified Pechini methods or mechanical mixing were used. The composite materials were characterized by XRD, BET, TPO and methane steam reforming reaction. Doping with complex oxides possessing a high mobility of the lattice oxygen and partial Ni substitution by the mixed conductor were applied to improve anode stability to coking.