Liquid Batteries Research Articles

Cross-Linked Solid Polymer-Based Catholyte for Solid-State Lithium-Sulfur Batteries

All-solid-state lithium-sulfur batteries (ASSLSBs) are a promising next-generation battery technology. They exhibit high energy density, while mitigating intrinsic problems such as polysulfide shuttling and lithium dendrite growth that are common to liquid electrolyte-based batteries. Among the various types of solid electrolytes, solid polymer electrolytes (SPE) are attractive due to their superior flexibility and high safety. In this work, cross-linkable polymers composed of pentaerythritol tetraacrylate (PETEA) and tri(ethylene glycol) divinyl ether (PEG), are incorporated into sulfur–carbon composite cathodes to serve a dual function as both a binder and electrolyte, as a so-called catholyte. The influence of key parameters, including the sulfur–carbon ratio, catholyte content, and ionic conductivity of the electrolyte within the cathode on the electrochemical performance, was investigated. Notably, the sulfur composite cathode containing 30 wt% of the PETEA-PEG copolymer catholyte achieved a high initial discharge capacity of 1236 mAh gS−1 at a C-rate of 0.1 and 80 °C.

Boosting oxygen reduction of single atomic iron sites by charge redistribution

Atomically dispersed porphyrin-type iron catalysts have demonstrated great potential to substitute platinum group metals for the oxygen reduction reaction (ORR), yet being subjected to limited active sites and sluggish O2 activation kinetics over the symmetrical planar four-coordinated FeN4 structure. Herein, the charge regulation on FeN4 site is achieved via non-bonding interaction of adjacent nitrogen over high-loading single atomic Fe catalysts to boost their intrinsic ORR activity. The single atomic Fe catalysts exhibit excellent alkaline ORR activity with a half-wave potential of 0.914 V versus reversible hydrogen electrode and tenfold higher kinetic current density than that of Pt/C catalysts. Both experimental and theoretical studies confirm that the secondary nitrogen compensation can anchor greater Fe atoms up to 5.44 wt% with sufficient O2 activation sites and simultaneously break the symmetrical charge distribution of FeN4 site to optimize the adsorption/desorption of oxygen intermediate for accelerating ORR kinetics. Moreover, the single atomic Fe catalysts demonstrate great practical application in liquid and solid zinc-air batteries with long-term cycling stability for 600 and 150 h, respectively, as well as superior flexibility in solid batteries.

A stable electrolyte interface with Li3PS4@Li7P3S11 for high-performance solid/liquid Li-S battery

The solid/liquid Li-S battery shows promise in solving both the polysulfide “shuttle effect” in liquid batteries and the interfacial contact in all-solid-state batteries. However, increasing the interfacial stability of the electrolyte and the solid electrolyte remains a challenge in the solid/liquid batteries. In this work, a high ionic conductivity Li3PS4 solution is synthesized using a nano-Li2S precursor, which is then utilized to form a solid electrolyte Li3PS4@Li7P3S11 via dip-coating. The Li3PS4@Li7P3S11 can form a dense protective interface Li3PS4-DME with the DOL/DME and DME electrolyte. This interface can prevent direct contact between the solid electrolyte and the electrolytes, efficiently inhibiting further solid electrolyte decomposition. The lithium symmetric battery with the solid electrolyte Li3PS4@Li7P3S11 is cycled stably for 1000 h, at a current density of 0.38 mA cm−2 and a capacity of 1.51 mA h cm−2. The Li-S battery with the solid electrolyte Li3PS4@Li7P3S11 can cycle stably for 300 cycles at 0.2C with a capacity of 600 mA h g−1 remaining.

Activity promotion of bifunctional catalysis by Se-doping and the application in rechargeable zinc-air batteries

Efficient bifunctional catalysts capable of catalyzing both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are required for the air electrode. Herein, the Se-doped FeNiP nanoparticles/N, P dual-doped carbon composite catalysts (FeNiP/SeNPC-2) were developed. The Se elements combine with various elements to form a compact heterogeneous material. At the same time, the Se-doping have modulated the crystal and surface structures, which have improved the catalytic activities of ORR and OER. The overpotential of OER was significantly negatively shifted, accompanied by a significant positive shift of the onset potential of ORR. FeNiP/SeNPC-2 has displayed an overpotential of 269 mV at the current density of 10 mA cm−2 for OER, and with a high half-wave potential (0.86 V) of ORR. The liquid zinc-air battery assembled using FeNiP/SeNPC-2 exhibited a power density of 171 mW cm−2 and stably charge-discharge cycled for 150 h. The solid-state zinc-air battery exhibited a power density of 88 mW cm−2 and stably charge-discharge cycled for 42 h. Subsequently, the solid-state zinc-air batteries of cylindrical hollow design are integrated as modules for driving devices.

Designable air-stable and dendrite-free Li metal anode via the oligomer layer for in-situ gel polymer batteries

Lithium (Li) metal anode has been an indispensable electrode material in the development of the future battery system, especially in the pursuit of energy density of the solid state battery. However, the poor air stability and dendrite problems are stumbling blocks to the practical application of Li metal anode. Herein, we design the poly(methyl methacrylate) (PMMA) oligomer coating layer for the surface of Li metal anode (Li-PMMA). The Li-PMMA anode can obtain hydrophobic oxygen resistance ability and maintain air stability for 48h in the environment of 70% relative humidity. When applied to the liquid battery, the PMMA oligomer can open the double bond by the catalysis of Li+ and repolymerize into the PMMA gel polymer electrolyte (GPE). As a result, the cathode and anode are cohered together by GPE to become an in-situ GPE battery. The GPE displays high ionic conductivity (7.92 mS cm-1) and perfect interfacial contact with various electrodes. The newly designed in-situ GPE is employed to Li||Li symmetric battery without separator, which can run up to 2000 h with the overpotential of only 2.8 mV. Applications of the in-situ GPE in Li-S battery and 5000mAh LiNi0.5Co0.2Mn0.3O2/Li pouch cell both obtain excellent electrochemical performance. Our strategy may provide a versatile and practical approach to promote the large-scale application for solid state Li metal batteries.

Biochemical and histopathological effects of copper oxide nanoparticles exposure on the bivalve Chambardia rubens (Lamarck, 1819).

Copper nanoparticles are widely incorporated into many applications, including air and liquid filters, wood preservatives, batteries, thermal and electrical conductivity, inks and skin products. Their potential toxicity and environmental fate, however, are poorly studied in the freshwater bivalves. The aim of the present study was to evaluate the different effects of copper oxide nanoparticles and ionic copper on the digestive glands and gills of the mussel Chambardia rubens. Mussels were treated with 100 and 1000 µg Cu L-1 of copper oxide nanoparticles (CuONPs) or ionic copper (Cu2+) for 3, 7, and 14 days. The Cu accumulation and markers of oxidative stress in the digestive glands and gills were evaluated. The results show that the digestive gland collected higher levels of the two forms of copper than the gills. Exposure to CuONPs or Cu2+ induced significant elevations in superoxide dismutase, glutathione peroxidase and lipid peroxidation. Notably, a significant decrease was observed in the glutathione levels after exposure to both copper forms. CuONPs only induced a significant increase in glutathione reductase and glutathione S-transferase. The ionic copper only induced a significant decrease in catalase activities in the gill tissues. Overall, CuONPs and Cu2+ provoked oxidative stress, and further research is needed to clarify their genotoxic and neurotoxic effects on freshwater mussels and other biota.

Bio-Assisted Atomically Dispersed Fe–N–C Electrocatalyst with Ultra-Low Fe Loading toward pH-Universal Oxygen Reduction Reaction and Neutral Zn-Air Battery

The advancement in the design of non-platinum noble metal-based oxygen reduction reaction (ORR) electrocatalysts with pH universality is crucial for the implementation of renewable energy devices in various environments. In this study, we present a convenient bio-assisted synthesis approach for the preparation of Fe–N–C catalysts, Fe@G-800/100. The Fe–N4 active sites, distributed atomically in the catalyst, confer remarkable ORR activity, leading to half-wave potentials (E1/2) of 0.91, 0.70, and 0.83 V vs RHE in alkaline, acidic, and neutral media, respectively. These values surpass the performance of state-of-the-art pH-universal ORR catalysts. We have also demonstrated the feasibility of constructing a cathode for a liquid Zn-air battery (ZAB) by utilizing Fe@G-800/100, with a rarely used PBS-derived neutral electrolyte. The resulting neutral ZAB exhibits a high open-circuit voltage, excellent charge–discharge cycling behavior, and significant specific capacity. Our findings provide valuable observations on the potential of pH-universal Fe–N–C catalysts and a roadmap for the design of neutral ZABs.

In Situ Constructed 3D Lithium Anodes for Long‐Cycling All‐Solid‐State Batteries

AbstractConstructing a 3D lithium metal anode has been demonstrated to be the most effective strategy to address its dendrite issue in liquid batteries. However, this promising approach has proved challenging to inherit in all‐solid‐state Li metal batteries (ASSLMBs) because of the rigidity of inorganic solid electrolytes (SEs), which constrains interfacial solid–solid ionic contact. Herein, a 3D Li anode is in situ constructed for ASSLMBs by spontaneous chemical reactions between halide SEs and Li metal. The in situ formed Li–Al alloys and well‐maintained sulfide SEs inside the 3D structure serve as continuous electron and Li+ transport pathways and facilitate the homogenous distribution of charge carriers. The lithiophilic Li alloy can regulate Li deposition behavior and enable uniform Li nucleation and deposition. Both the Li||Li symmetric and full batteries exhibit good electrochemical performance at high current density. This work provides a universal strategy and new insight perspective to construct 3D Li for high‐performance ASSLMBs.

Electrodeposition of bimetal Ni-Co oxide as a bifunctional electrocatalyst for rechargeable zinc air battery

Zinc air battery is a promising candidate green energy storage due to its high energy density and low-cost. However, most of the preparation of air cathode in the literature involves a lengthy and inefficient process of mixing catalyst powders with a polymeric binder. Herein, we synthesize bimetal Ni-Co oxide through a simple electrodeposition technique followed by annealing at a low temperature under atmospheric conditions. The addition of cobalt at various contents significantly alters surface morphology from tiny nanoparticles to a 2D nano-sheet structure. The performance of the as-prepared catalysts were firstly evaluated toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline solution. Our results show that the incorporating cobalt in the NiO host structure not only improve the OER but also the ORR activities. The required potential to drive OER at a current density of 10 mA/cm2 and the half-wave potential for ORR using the NC-2 catalyst are 1.567 and 0.855 V vs. RHE, respectively, resulting a delta potential of 0.712 V. Furthermore, we demonstrate the practical application of the NC-2 catalyst as the air cathode electrode for assembling a liquid zinc air battery device. The battery test reveals that NC-2 has an open circuit potential of 1.36 V and a specific capacity of 714 mAh/gZn with an excellent stability performance for about 80 h. Our findings suggest that bimetal Ni-Co oxide is a promising catalyst for enhancing the performance of zinc air batteries.

Tailoring activity of iron phthalocyanine by edge-nitrogen sites induced electronic delocalization

Fe-N-C catalysts have been recognized as the most satisfactory candidates alternatively to Pt-based catalysts for oxygen reduction reaction (ORR). However, fine-tailoring of their intrinsic ORR catalytic activity still remains a great challenge due to the inferior accessibility and intrinsic activity of FeNx moieties. Herein, one order of magnitude activity enhancement of pristine Fe-N-C through cooperating with nitrogen-doped carbon micro-flower is achieved. The axial coordination effect between Fe active center and nitrogen atoms in support can break the electronic distribution symmetry of FeNx moieties and induce the electron delocalization on Fe active center and the electron localization on N, respectively, which favor the adsorption behavior of *OH intermediate. As a result, the catalyst exhibits a remarkable half-wave potential of 0.9 V and a high kinetic current density of 74.04 mA cm−2 at 0.85 V. In addition, when utilized as a cathode catalyst of liquid Zn-air batteries (ZABs), it possesses excellent electrochemical performance, for example, a high open circuit voltage (OCV) and peak power density of 1.59 V and 170.09 mW cm−2, respectively. This work provides a new understanding into the activity enhancement mechanism of Fe-N-C catalysts, and inspires electronic delocalization of active sites for adjusting catalytic activity.

Self‐Polarized Organic–Inorganic Hybrid Ferroelectric Cathode Coatings Assisted High Performance All‐Solid‐State Lithium Battery

AbstractFerroelectrics can significantly boost electrochemical performances of all‐solid‐state batteries by constructing built‐in electric field to reduce the space charge layer at cathode/solid‐state electrolyte interface. However, the construction mechanism of ferroelectric built‐in electric field is poorly understood. Herein, the guanidinium perchlorate (GClO4) ferroelectrics as the cathode coatings in the LiCoO2‐based all‐solid‐state lithium battery are reported, which has state‐of‐the‐art specific capacity of 210.6 mAh g−1 (91.6% of the liquid battery). Systematic studies reveal that the flexoelectric effect originating from the lattice mismatch between GClO4 and LiCoO2 gives GClO4 coatings the single‐domain state and upward self‐polarization. Consequently, a vertically downward built‐in electric field is generated relative to the cathode, which transports the lithium ions inside the electrolyte to the three‐phase interface to alleviate the space charge layer. These findings highlight that the microstructural characteristics of ferroelectric and electrode materials are the primary concern for building an effective built‐in electric field.

Determining the Role of Ion Transport Throughput in Solid-State Lithium Batteries.

Solid-state lithium metal batteries (SSLMBs) are promising candidates for high-energy-density energy storage devices. However, there still lacks an evaluation criterion to estimate real research status and compare overall performance of the developed SSLMBs. Herein, we propose a comprehensive descriptor, Li+ transport throughput ( ), to estimate actual conditions and output performance of the SSLMBs. The is defined as molar number of Li+ passing through unit area of electrode/electrolyte interface in an hour (mol m-2 h-1 ) during cycling of battery, which is a quantizable value after taking complex aspects including cycle rate, electrode areal capacity and polarization into account. On this basis, we evaluate the of liquid, quasi-solid-state and solid-state batteries, and highlight three key aspects to achieve high value of via building highly efficient cross-phase, cross-gap and cross-interface ion transport in the solid-state battery systems. We believe that the new concept of provides milestone guidelines towards large-scale commercialization of SSLMBs.

Low-temperature crystal structures of the solvent dimethyl carbonate

Dimethyl carbonate (DMC) is an important industrial solvent but is additionally a common component of liquid lithium-ion battery electrolytes. Pure DMC has a melting point of 277 K, so encountering solidification under outdoor climatic conditions is very likely in many locations around the globe. Even eutectic, ethylene carbonate:dimethyl carbonate commercial LiPF6 salt electrolyte formulations can start to solidify at temperatures around 260 K with obvious consequences for their performance. No structures for crystalline DMC are currently available which could be a hindrance for in situ battery studies at reduced temperatures. A time-of-flight neutron powder diffraction study of the phase behavior and crystal structures of deuterated DMC was undertaken to help fill this knowledge gap. Three different orthorhombic crystalline phases were found with a previously unreported low-temperature phase transition around 50–55 K. The progression of Pbca → Pbcm → Ibam space groups follow a sequence of group–subgroup relationships with the final Ibam structure being disordered around the central carbon atom.

Fundamentals, preparation, and mechanism understanding of Li/Na/Mg-Sn alloy anodes for liquid and solid-state lithium batteries and beyond

Fundamentals, preparation, and mechanism understanding of Li/Na/Mg-Sn alloy anodes for liquid and solid-state lithium batteries and beyond

Liquid metal welding enabling high loading binder/carbon-free layered oxide cathode toward high-performance liquid and solid-state battery

Liquid metal welding enabling high loading binder/carbon-free layered oxide cathode toward high-performance liquid and solid-state battery

Efficient MnO and Co nanoparticles coated with N-doped carbon as a bifunctional electrocatalyst for rechargeable Zn-air batteries

Developing the low-cost, durable, and efficient bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays an important role in the commercial implementation of the Zn-air batteries. Herein, we design and synthesize the MnO and Co nanoparticles coated with N-doped carbon (MC@NC) as an excellent bifunctional oxygen electrocatalyst. It is found that the optimal MC@NC-0.3 exhibits outstanding ORR performance with a positive half-wave potential of 0.82 V and excellent OER activity with a small overpotential of 360 mV at 10 mA cm−2. When applied in the liquid Zn-air battery, MC@NC-0.3 displays a high maximum power density of 153 mW cm−2, a large specific capacity of 776 mAh g−1 and the excellent cycling stability with a negligible increase after 300 h. Furthermore, the fiber-shaped all-solid-state Zn-air battery also displays remarkable stability at high current density. This study offers a facile strategy to construct a high-efficient, low-cost, and durable transitional metal-based bifunctional electrode for renewable energy applications.

Gram-scale synthesis and unraveling the activity origin of atomically dispersed Co-N4O sites toward superior electrocatalytic oxygen reduction

Exploring highly efficient nonprecious metal-based single-atom catalysts (SACs) toward the electrocatalytic oxygen reduction reaction (ORR) is critical for the sustainable development of ORR-related energy conversion and storage systems. However, the scalable synthesis, delicate regulation of the coordination environment and molecular-level elucidation of the electrocatalytic mechanism remain challenging. Herein, we report a facile gram-scale synthesis of atomically dispersed Co sites anchored on N-doped carbon nanofibers (noted as Co-SA@N-CNFs) via a reliable predesigned phenolic resin-mediated strategy for efficient oxygen reduction electrocatalysis. The local coordination configuration of the single-atomic Co sites is proposed as the Co-N4O moiety with one O atom in the axial direction perpendicular to the Co-N4 plane. Theoretical calculations uncover that, compared with the common Co-N4 single sites, the formation of Co-N4O configuration is beneficial to reduce the reaction energy barrier, adjust the bond length between the metal sites and the intermediates, and also increase the electric conductivity. Therefore, the Co-SA@N-CNFs demonstrated distinguished ORR activity, outstanding electrochemical stability and methanol tolerance in KOH electrolyte. Furthermore, when assembled in liquid and flexible solid-state rechargeable zinc-air batteries (ZABs), the Co-SA@N-CNFs-equipped ZABs exhibited higher power densities, larger specific capacities and extraordinary cycling performance, compared with the Pt/C-based ZABs. The simple and robust methodology for the mass production of SACs and the engineered coordination environment for performance optimization inspire the future design of a wide range of SACs for energy devices.

One-pot synthesis of NiFe-MOF/NiFe2O4 hollow spheres and their application as bifunctional ORR/OER electrocatalysts in Zn-air batteries

The development of bifunctional electrocatalysts to reduce the polarization loss is essential to enhance the performance of Zn-air batteries. The combination of metal-organic frameworks (MOFs) with metal or metallic compounds provides a way to integrate their merits and effectively improve their electrocatalytic performances. However, previous synthesis of MOFs/metal oxides usually involves high-temperature calcination, which makes it difficult to control their morphologies. In this work, through a ligand-insufficient and high temperature controlled solvothermal reaction, innovative NiFe-MOF/NiFe2O4 hollow nanospheres were one-pot prepared without using any shape-controlled agent or calcination process. The as-obtained NiFe-MOF/NiFe2O4 shows better ORR and OER performance than pure NiFe-MOF and NiFe2O4, suggesting a synergetic effect between NiFe-MOF and NiFe2O4. The maximum power density of the liquid Zn-air battery assembled using NiFe-MOF/NiFe2O4 as the air electrode catalyst is 158.4 mW cm−2 at 246.1 mA cm−2. This work offers fresh thoughts into designing highly efficient MOF-derived electrocatalysts.

Highly Stable and Active Flexible Electrocatalysts Derived from Lotus Fibers

AbstractThe stability and activity of electrocatalysts are fundamental in energy‐related applications (e.g., hydrogen generation and energy storage). Electrocatalysts degrade over time when the active centers are not strongly anchored to the support. However, if the active centers are too strongly anchored, the activity of the electrocatalysts decreases due to reduced accessibility to reactants. Herein, a strategy is presented to balance the stability and activity of different active materials using a natural and flexible support material that can be woven and carbonized. Lotus fibers, which have surface hydroxyl and phenolic groups, high mechanical strength, and a mesoscale porosity post‐pyrolysis, are used to load diverse functional metal‐containing materials such as metal–organic frameworks, 2D materials, metal sulfide nanoparticles, metal ions, and high‐entropy alloys. After pyrolysis, the electrocatalysts display flexibility, high catalytic performance, and long‐term stability, outperforming commercial benchmarks (e.g., Pt/C) in specific scenarios for water splitting, liquid batteries, and flexible electronics.

Free-Standing and Flexible Garnet-PVDF Ceramic Polymer Electrolyte Membranes for Solid-State Batteries

Solid-state batteries have been getting considerable attention in recent times due to the safety issues associated with liquid electrolyte-based batteries. However, most rigid solid electrolytes are vulnerable to mechanical strains, so implementation in a commercial battery needs proper modifications. Polymer-type flexible membranes could overcome the size and fragility. Herein, we propose a straightforward preparation of flexible and thin ceramic polymer electrolyte membranes combined with the advantage of garnet-structured fast lithium-ion conductors (Li6.28Al0.24La3Zr2O12) with polyvinylidene fluoride polymers. An 8:2 ratio of garnet to polymer has been employed to create a free-standing flexible ceramic polymer electrolyte through tape casting. The membrane showed excellent electrochemical performance with good conductivity and thermal–electrochemical stability. A facile way of polymer electrolyte casting over lithium iron phosphate electrode material, which contains 5 wt % garnet material, has been adapted to enhance the electrode–electrolyte contact. The cell has offered significantly notable performance. This way, the benefit of solid-state electrolytes could extend to the large-scale production of solid-state batteries with extended safety.