The positive electrode|electrolyte interface plays an important role in all-solid-state Li batteries (ASSLBs) based on garnet-type solid-state electrolytes (SSEs) like Li6.4La3Zr1.4Ta0.6O12 (LLZTO). However, the trade-off between solid-solid contact and chemical stability leads to a poor positive electrode|electrolyte interface and cycle performance. In this study, we achieve thermodynamic compatibility and adequate physical contact between high-entropy cationic disordered rock salt positive electrodes (HE-DRXs) and LLZTO through ultrafast high-temperature sintering (UHS). This approach constructs a highly stable positive electrode|electrolyte interface, reducing the interface resistance to 31.6 Ω·cm2 at 25 °C, making a 700 times reduction compared to the LiCoO2 | LLZTO interface. Moreover, the conformal and tight HE-DRX | LLZTO solid-state interface avoids the transition metal migration issue observed with HE-DRX in liquid electrolytes. At 150 °C, HE-DRXs in ASSLBs (Li|LLZTO | HE-DRXs) exhibit an average specific capacity of 239.7 ± 2 mAh/g at 25 mA/g, with a capacity retention of 95% after 100 cycles relative to the initial cycle—a stark contrast to the 76% retention after 20 cycles at 25 °C in conventional liquid batteries. Our strategy, which considers the principles of thermodynamics and kinetics, may open avenues for tackling the positive electrode|electrolyte interface issue in ASSLBs based on garnet-type SSEs. The positive electrode/electrolyte interface is crucial for the performance of all-solid-state lithium batteries. Here, authors use a sintering technique to form a conformal interface between high-entropy disordered rock salt electrodes and garnet-type electrolytes to reduce interfacial resistance.

Protonic ceramic cells (PCCs) have drawn great attention on account of their reversibility and high efficiency. We propose a strategy to design a composite proton conductor composed of BaZr0.1Ce0.7Y0.2O3-delta (BZCY) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) sintered through ultrafast high-temperature sintering, showing a reduced sintering temperature of 1170 degrees C. BZCY particles are uniformly distributed within a continuously conformal framework formed by the low-melting LLZTO phase. The unique structural design avoids the sharp edge between BZCY particles caused by the soft LLZTO phase, resulting in faster proton migration at the grain boundary region. As a result, the new composite electrolyte exhibits a proton conductivity of 0.028 S cm(-1) at 600 degrees C, 4.5 times that of BZCY. Furthermore, we demonstrate that LLZTO exhibits considerable proton conductivity by combining our experimental and simulation results. This research advances the potential of combining proton and lithium-ion conducting composites with high proton conductivity and low sintering temperature for PCCs.

Micron-sized Si anodes garner renewed attention due to their advantages of low cost, small specific surface area, and high energy density. However, micron-sized Si anodes undergo significant volume changes during lithiation/delithiation, leading to particle cracking and pulverization. This study employs the tape casting method and ultrafast high-temperature sintering technology to construct a porous sheet, within which a solid framework constrains the Si particles. In rate performance tests, when the current density rises to 1 A g-1, the micron-sized Si in the porous sheet demonstrates a delithiation capacity of 2145 mAh g-1, compared to 113 mAh g-1 for the pristine Si, showing efficient ion and electron conductive pathways in the framework. When cycled at 0.3 A g-1, the delithiation capacity of the ball-milled micron-sized Si in the porous sheet is 1496 mAh g-1 after 100 cycles, in contrast to 95 mAh g-1 for the pristine Si. The enhanced cycling stability of Si in the porous sheet results from the strong mechanical constraint imposed by the solid framework, which suppresses volume changes, inhibits particle cracking, and reduces solid electrolyte interphase growth. This strategy of constructing porous sheets and utilizing solid-solid bonding to constrain Si particles represents a novel approach for Si anode modification.

Robust catalytic materials with high activity and stability play important roles in energy conversion and storage devices such as protonic ceramic fuel cells (PCFCs), in which a favourable cathode should possess high oxygen ion, proton and electron triple conductivities, and superior surface oxygen exchange kinetics. Herein, a thermal-driven self-construction phenomenon in cation-nonstoichiometric Ba1+xGd1-xCo2O6-delta is reported, accordingly developing a new type of nanocomposite, that is, double perovskite BaGdCo2O6-delta (DP-BGCO) anchored by perovskite-derived BaCoO3-delta (P-D-BCO) nanoparticles, which, used as the cathode of PCFCs, demonstrates low area-specific resistances of 0.053 and 0.026 ohm cm-2 respectively at 650 and 700 degrees C over BaZr0.3Ce0.5Y0.1Yb0.1O3-delta protonic electrolyte and attractive peak power densities of 0.87 (650 degrees C) and 1.15 W cm-2 (700 degrees C) with outstanding stability, much superior to the similar cell with single-phase BCO or BGCO cathodes. The synergy between the two components brings the outstanding performance with the mixed oxygen ion and electronic conducting perovskite-derived oxide showing superior catalytic activity for oxygen reduction reaction while the double perovskite provides good bulk protonic conductivity to enlarge reaction sites. Such selective self-construction, well manipulated through the A-site cation stoichiometry engineering, provides a facile way for developing new high-performance electrocatalysts with broad application potential. Self-assembly at the nanoscale enables spontaneous growth of perovskite-derived oxide over double perovskite oxide. The specific composition and unique structure generate a synergetic effect between them and enable superior cathodic electrochemical reactions, when being used as cathode materials of protonic ceramic fuel cells. As a consequence, the cell performances are greatly boosted. image

Perovskite oxides show great promise as an alternative catalyst to the conventional nickel cermets for CO2 reduction reactions (CO2RR) in solid oxide electrolysis cells (SOECs) owing to their advantages of redox stability and coking resistance. Nevertheless, practical applications of these oxides are prevented largely by their poor CO2RR activities. Herein, a novel donor and acceptor co-doped nonstoichiometric double perovskite, La0.3Sr1.55Fe1.5Ni0.1Mo0.4O6-delta (LSFNM), is developed with in situ exsolved FeNi3 nanoparticles to efficiently catalyze CO2RR in SOECs. Pure CO2 electrolysis over the impregnated FeNi3@LSFNM catalysts is evaluated on two types of SOECs-one with thin (ZrO2)(0.89)(Sc2O3)(0.1)(CeO2)(0.01) (SSZ) electrolytes supported on 430L alloys and the other with thin La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) electrolytes supported on impregnated SmBa0.5Sr0.5CO2O5+delta (SBSCO)@LSGM anodes, producing unprecedently high current densities of 2.84 A cm(-2) for the former and 3.07 A cm(-2) for the latter at 1.5 V and 800 degrees C. Experimental analysis and density-functional theory (DFT) calculations reveal collective synergistic catalysis of oxygen vacancies (V-(O)double over dot), the doping Ni2+ ions and FeNi3 nanoparticles via the cooperative V-(O)double over dot-O(CO2), and Ni(II)-C(sp) and Ni(0)-O(CO2) interactions in LSFNM, not only facilitating CO2 chemisorption on oxygen vacancies but also destabilizing and dissociating surface carbonates in the vicinity of FeNi3 spontaneously into CO.

Low ion and electron conductivities of the cathode and poor cathode interface performance severely limit the application of garnet solid-state batteries. While various approaches have been developed to improve the cathode interface contact or enhance ion and electron transport, none of these methods can simultaneously achieve high interfacial electrochemical activity and chemical stability. In this work, we propose to develop a single-phase garnet-type mixed ionic and electronic conductor (MIEC) as the cathode framework, which is expected to achieve the unification of high activity and high stability at the cathode interface. Combining first-principles calculations and ultrafast sintering techniques, we have synthesized and screened a series of garnet-type MIECs by introducing transition metals into garnet SSEs. Among the garnet-type MIECs, Li43Fe3La24Zr12Ta4O96 (3Fe) not only exhibits an excellent electronic conductivity of up to 2.87 × 10−4 S cm−1 but also maintains an ionic conductivity of 4.57 × 10−5 S cm−1. The high electronic conductivity is believed to originate from the high-temperature reduction phase formed during the rapid sintering process under inert conditions. A small polaron hopping mechanism is proposed to explain the electronic conductivity based on electronic structure calculations and activation energy analysis. Since garnet-type MIECs have the same crystal structure as garnet solid-state electrolytes (SSEs) and transition metal elements similar to those of oxide cathode materials, they potentially have good cosintering stability with both electrolytes and cathodes. This work provides a new strategy to solve the cathode interface problem in garnet solid-state batteries.

Garnet type solid-state electrolytes (SSEs) possess high stability against Li metal, intrinsic safety, and wide electrochemical window. To achieve the all-solid-state batteries (ASSBs) with high gravimetric/volumetric energy density and high power density, flat thin garnet SSEs with a high ionic conductivity of > 10(-4) S/cm are required. However, the current fabrication processes are challengeable to maintain both the high ionic conductivity and the flat skeleton due to the severe Li loss during processing and the fragile nature of thin films. Herein, we introduce a rapid Li compensation (RLC) technique that combines the ultra-fast high-temperature sintering (UHS) technique with the tape casting process to produce highly ionic conductive, flat garnet SSE thin films. The freestanding Li6.4La3Zr1.4Ta0.6O12 (LLZTO) thin film with a thickness of 40 mu m, fabricated using this technique, displays a surface roughness of 5 mu m and a relative density of 95%. After a 10-seconds Li compensation, the compensated LLZTO film displays an ionic conductivity of 4.3 x 10(-4) S/cm, 2 times higher than the non-compensated one. As a proof of concept, this RLC technique proposes a new strategy for the fabrication of high-performance ceramic thin films and also lays a solid foundation for the application of ASSBs.

Composite solid-state electrolytes (SSEs) can improve the flexibility of the oxide SSEs to decrease the interfacial resistance between the electrolytes and the electrodes. However, the ceramic nanofillers within the composite SSEs suffer from the agglomeration at high concentrations, decreasing the ion conductivities. In this study, a continuous nanocrystal Li6.5La3Zr1.5Ta0.5O12 (LLZTO) skeleton is prepared by the ultrafast high-temperature sintering (UHS) together with tape-casting. Due to the short sintering time of-5 s from precursors, the LLZTO grains are restrained to-300 nm with limited Li loss. Even with trace solvent (3 wt%), the composite SSE membrane exhibits an ion conductivity of 5 x 10-4 S center dot cm- 1,-50 times higher than the DOL electrolyte (1 x 10-5 S center dot cm- 1, 8 wt% solvent), which further proves the high Li-ion conductivity of the nanocrystal LLZTO skeleton. The composite SSE membrane exhibits a critical current density of 3.4 mA center dot cm- 2, among the highest reported values for ceramic-polymer SSEs. The Li/composite SSEs/Li symmetric cells can cycle -120 h at the current density from 0.2 to 0.4 mA center dot cm- 2. The LiFePO4/LLZTO-PEGDA composite SSEs/Li full cell exhibits a high specific discharge capacity of-150 mAh center dot g- 1 for-50 cycles with a Coulombic efficiency of-97%. To explore the processability of the membrane with large size, we also demonstrate a pouch cell (2 cm x 5 cm) with a high specific capacity of-150 mAh center dot g-1 for-25 cycles and a capacity retention of-94.5%. This work paves a new way to manufacture the nanocrystal ceramic SSE skeleton for high energy density all-solid-state batteries.

Garnet-type Li7La3Zr2O12 (LLZO) has high ionic conductivity and good compatibility with lithium metal. High-temperature processing has been proven an effective method to decrease the interface resistance of cathode|LLZO. However, its application is still hindered by the interlayer co-diffusion with the cathode and high sintering temperature (>1200 & DEG;C). In this work, a new garnet-type composite solid-state electrolyte (SSE) Li6.54La2.96Ba0.04Zr1.5Nb0.5O12-LiCoO2 (LLBZNO-LCO) is firstly proposed to improve the chemical stability and electrochemical properties of garnet with high-temperature processing. Small doses of LCO (3%) can significantly decrease the LCO|SSE interface resistance from 121.2 to 10.1 X cm2, while the sintering temperature of garnet-type LLBZNO decreases from 1230 to 1000 & DEG;C. The all-solid-state battery based on the sintered LLBZNO-LCO SSE exhibits excellent cycling stability. Our approach achieves an enhanced LCO|SSE interface and an improved sintering activity of garnet SSE, which provides a new strategy for optimizing the comprehensive performance of garnet SSE.& COPY; 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Abstract Solid‐state electrolytes (SSEs) hold a critical role in enabling high‐energy‐density and safe rechargeable batteries with Li metal anode. Unfortunately, nonuniform lithium deposition and dendrite penetration due to poor interfacial solid–solid contact are hindering their practical applications. Here, solid‐state lithium naphthalenide (Li‐Naph(s)) is introduced as a plastic monolithic mixed‐conducting interlayer (PMMCI) between the garnet electrolyte and the Li anode via a facile cold process. The thin PMMCI shows a well‐ordered layered crystalline structure with excellent mixed‐conducting capability for both Li+ (4.38 × 10–3 S cm–1) and delocalized electrons (1.01 × 10–3 S cm–1). In contrast to previous composite interlayers, this monolithic material enables an intrinsically homogenous electric field and Li+ transport at the Li/garnet interface, thus significantly reducing the interfacial resistance and achieving uniform and dendrite‐free Li anode plating/stripping. As a result, Li symmetric cells with the PMMCI‐modified garnet electrolyte show highly stable cycling for 1200 h at 0.2 mA cm–2 and 500 h at a high current density of 1 mA cm–2. The findings provide a new interface design strategy for solid‐state batteries using monolithic mixed‐conducting interlayers.

Developing mixed proton-electron conductors (MPECs) is essential to accelerate the sluggish air electrode reaction kinetics of protonic ceramic electrochemical cells, for their unique conduction behaviors can amazingly extend the active reaction zone to the whole electrode surface. Hydration enthalpy plays a key role in determining the conduction behaviors of MPECs, but its underlying factors and modulation mechanisms are still unclear. In this work, an efficient and reliable strategy to theoretically predict the hydration enthalpies of MPECs is first proposed, and then, affecting factors of hydration enthalpies are investigated based on the calculation results on M-doped BaFeO3-delta and Ba0.5Sr0.5FeO3-delta series (M = Zr4+, Sn4+, Ti4+, and Nb5+). Remarkably, the volume per atom (VPA) is found as the decisive factor of hydration enthalpies. This finding prompts new thinking about the rational design of novel MPECs.

Due to their unique properties, high surface area carbon nanomaterials such as carbon nanotubes and graphene have been widely used in energy storage applications. However, it is still difficult and expensive to synthesize carbon nanotubes and graphene at large-scales. Hence, there is still a need for the development of low-cost and facile synthesis techniques for porous carbon materials with highly accessible surface areas. A facile and solution-based, spray pyrolysis synthesis technique which was used to synthesize individual carbon nanospheres with specific surface area (SSA) up to 1106 m2/g using a novel ZnO catalyzed reaction. The carbon nanosphere diameters were tunable from 10 nm to several micrometers by varying the precursor concentrations. Solid, hollow, and porous carbon nanospheres were achieved by simply varying the ratio of catalyst and carbon source without using any templates. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g, were observed, with no capacitance loss after 20,000 cycles. The performance of the carbon nanospheres as electrodes in Li-ion batteries were also investigated. The direct pyrolysis of sugar and zinc nitrate mixtures was employed to obtain foam-like carbons with specific surface area (SSA) up to 2340 m2/g without using any hard templates. The role of the ZnO nanoparticles formed from the decomposition of zinc nitrate and the effects of high temperature annealing on the formation of the high SSA carbon foams were systematically studied. Due to the facile and quick reaction conditions, these carbon foams carbons could be easily synthesized at a large scale. When used as supercapacitor electrode materials, a specific capacitance up to 280 F/g was achieved at current density of 0.1 A/g, and still remained as high as 207 F/g even at a high current density of 10 A/g. References: C. Wang, Y. Wang, J. Graser, R. Zhao, F. Gao, M.J. O’Connell, ACS Nano, 7, 11156-11165 (2013). V. Etacheri, C. Wang, M.J. O’Connell, C.K. Chan, V.G. Pol, J. Mater. Chem. A, 3, 9861-9868 (2015). C. Wang, M.J. O’Connell, C.K. Chan, ACS Appl. Mater. Interfaces, 7, 8952 (2015).

Photocatalysis is an attractive treatment method for removing hexavalent chromium (Cr(VI)) from water. Thus far, photocatalytic reduction of Cr(VI) has been investigated mostly using TiO2 photocatalysts in acidic water solutions. Here we investigate Cr(VI) removal using zinc oxide (ZnO), tungsten trioxide (WO3), and sodium tantalate (NaTaO3), metal oxides that display good activity for other photocatalytic reactions such as water splitting, as well as titanium oxide (TiO2, Evonik P90). The efficiency for Cr(VI) removal using these photocatalysts was investigated in synthetic neutral and alkaline water, as well as in cooling tower blowdown water. The effect of several additives used in water treatment processes on the Cr(VI) removal rate was also studied. For NaTaO3, citric acid was found to have a detrimental effect to Cr(VI) removal, while sodium formate, ammonium chloride, and sodium sulfite were beneficial. While sulfite alone could chemically reduce Cr(VI), sulfite in combination with a photocatalyst resulted in faster and complete removal of Cr(VI) in 10 min using a SO32-/Cr(VI) ratio >35 in pH similar to 8 solutions. NaTaO3 was found to display the highest Cr(VI) removal rates on a photon basis at pH 3 and in the presence of sodium sulfite, while ZnO and TiO2 showed the best performance in pH 7 and cooling tower blowdown water. (C) 2015 Elsevier B.V. All rights reserved.