Commercial Electrolyte Research Articles

Functional and Environmental Performances of Novel Electrolytic Membranes for PEM Fuel Cells: A Lab-Scale Case Study

Despite being the most employed polymer electrolyte for proton exchange membrane fuel cells (PEMFCs), Nafion® has several limitations: expensiveness, poor performance when exposed to temperatures higher than 80 °C, and its potential as a source of environmentally persistent and toxic compounds (i.e., per- and polyfluoroalkyl substances, known as PFASs) when disposed of. This work explores the functional and environmental performances of three potential PFAS-free alternatives to Nafion® as electrolytic membranes in PEMFCs: sulfonated graphene oxide (SGO), graphene oxide-naphthalene sulfonate (GONS), and borate-reinforced sulfonated graphene oxide (BSGO). Investigated via ATR-FTIR spectroscopy, TGA, and cross-sectional SEM, the membranes show an effective functionalization of GO and good thermal stability. Functional properties are determined via Ion Exchange Capacity (IEC) evaluation, Electrochemical Impedance Spectroscopy, and tensile tests. In terms of IEC, the innovative materials outperform Nafion® 212. Proton conductivities at 80 °C of SGO (1.15 S cm−1) and GONS (1.71 S cm−1) are higher than that of the commercial electrolyte (0.56 S cm−1). At the same time, the membranes are investigated via Life Cycle Assessment (LCA) to uncover potential environmental hotspots. Results show that energy consumption during manufacture is the main environmental concern for the three membranes. A sensitivity analysis demonstrates that the impact could be significantly reduced if the production procedures were scaled up. Among the three alternatives, SGO shows the best trade-off between proton conductivity and environmental impact, even though performance results from real-life applications are needed to determine the actual environmental consequences of replacing Nafion® in PEMFCs.

Dynamics of polymer electrolyte with LiTFSI via Quasi-Elastic Neutron Scattering

Most lithium batteries offer a wide range of applications. However, safety issues are still an unresolved issue for several applications. To solve the safety issue of Li-ion batteries, solid polymer electrolyte is a promising candidate to replace commercial liquid electrolyte. A 4-arm star poly(ethylene oxide) polymer with LiTFSI salt as an electrolyte was studied. The dynamics of this polymer were explored with the Quasi-Elastic Neutron Scattering technique. Furthermore, the influence of temperature and Li salt concentration on the polymer dynamics was investigated. The dynamics of the polymer ends of the arm show much higher flexibility than the core parts making those types of polymers attractive for further studies in battery research.

Ultrahigh-voltage aqueous electrolyte for wide-temperature supercapacitors

This work provides a promising strategy to expand the wide electrochemical stability window of low concentrated aqueous electrolytes to replace commercial organic electrolytes with the aim of pushing aqueous supercapacitors into practical applications.

Laser induced flexible micro-supercapacitor for pressure sensing

Portable, wearable electronic devices have spurred the rapid development of flexible and stretchable energy harvesting/storage devices with high energy density, superior mechanical stability, and long cycle life. Micro-supercapacitor (MSC) has attracted wide interest due to their advantages of high power density, rapid charge and discharge, and long cycle life. Fabrication of flexible supercapacitors based on laser induced graphene (LIG) has shown strong advantages and potential for flexible sensor power supply. The purpose of this paper is to propose and develop a laser induced flexible micro-supercapacitor (FMSC) for pressure sensors. FMSC is manufactured from a planar forked finger electrode made of graphene induced by CO2 laser radiation commercial Polyimide (PI) film and PVA polymer gel electrolyte. The FMSCs prepared by this method exhibit good electrochemical properties and excellent mechanical properties. The microscopic morphology of LIG was investigated using SEM, and the optimal laser-induced power was determined to be 12.5%. In this paper, a novel fork-finger electrode pattern was applied to improve the performance of FMSCs by optimizing the structure of planar interdigital electrodes, and the FMSCs prepared at 12.5% power showed excellent supercapacitance performance at a voltage window of 0.8 V with a specific capacitance of 2.21 mF/cm2. The FMSCs were made by assembling commercial PI films, PVA, and H3PO4 simple materials, which makes it possible to prepare FMSCs at low cost and high efficiency based on laser direct writing technology. FMSCs provide energy to the flexible sensors and continuously collect energy to charge FMSCs through an integrated flexible energy harvester, which makes FMSCs promising for flexible self-powered wireless sensing platforms.

Acid-scavenging separators promise long-term cycling stability of lithium-ion batteries

Acid-scavenging separators are an efficient way to inhibit the acidification of traditional LiPF6-containing electrolytes. This paper reviews the development and achievements of acid-scavenging separators to enhance their practical application capabilities and future developments.

Novel ternary fluorinated electrolyte's enhanced interfacial kinetics enables ultra-low temperature performance of lithium-ion batteries

A novel ternary fluorinated electrolyte (F-FFN) has been devolved that retained 61% of its RT capacity at −50 °C with a low Ea,CT of 55.71 kJ mol−1 compared to the commercial electrolyte, which retained only 25% of its RT capacity at −25 °C.

Spatially Confined LiF Nanoparticles in an Aligned Polymer Matrix as the Artificial SEI Layer for Lithium Metal Anodes.

The uncontrollable growth of lithium (Li) dendrites and the instability of the Li/electrolyte interface hinder the development of next-generation rechargeable lithium metal batteries. The combination of inorganic nanoparticles and polymers as the artificial SEI layer shows great potential in regulating lithium-ion flux. Here, we design spatially confined LiF nanoparticles in an aligned polymer matrix as the artificial SEI layer. A high dielectric polymer matrix homogenizes the electric field near the surface of lithium metal. Aligned pores with LiF nanoparticles promote the lithium-ion transport across the artificial SEI layer. The synergistic effect of the highly polar β-phase PVDF and LiF nanoparticles provides high stability over 900 h for the Li//Li symmetrical cell. Besides, a Li//LFP full battery equipped with this artificial layer shows good performance in the commercial carbonate electrolyte, demonstrating the great potential of this protective film in lithium metal batteries.

An Electrolyte with Elevated Average Valence for Suppressing the Capacity Decay of Vanadium Redox Flow Batteries.

Nafion series membranes are widely used in vanadium redox flow batteries (VRFBs). However, the poor ion selectivity of the membranes to vanadium ions, especially for V2+, results in a rapid capacity decay during cycling. Although tremendous efforts have been made to improve the membrane's ion selectivity, increasing the ion selectivity without sacrificing the proton conductivity is still a challenging issue. In this work, instead of focusing on enhancing the membranes' ion selectivity, we develop an efficient valence regulation strategy to suppress the capacity decay caused by the crossover of V2+ in VRFBs. Despite the discharge capacity of the VRFB with the elevated average valence electrolytes (V3.68+) being slightly lower than that with commercial electrolytes (V3.50+) in the first 35 cycles, the accumulated discharge capacity in 400 cycles is improved by 52.33%. Moreover, this method is efficient, is easy to scale up, and provides deep insights into the capacity decay mechanism of VRFBs.

Effect of Cross-Linking and Surface Treatment on the Functional Properties of Electrospun Polybenzimidazole Separators for Lithium Metal Batteries.

In this work, electrospun PBI separators with a highly porous structure and nanofiber diameter of about 90-150 nm are prepared using a multi-nozzle under controlled conditions for lithium metal batteries. Cross-linking with α, α-dibromo-p-xylene and surface treatment using 4-(chloromethyl) benzoic acid successfully improve the electrochemical as well as mechanical properties of the separators. The resulting separator is endowed with high thermal stability and excellent wettability (1080 to 1150%) with commercial liquid electrolyte than PE and PP (Celgard 2400) separators. Besides, attractive cycling stability and rate capability in LiFePO4/Li cells are attained with the modified separators. Prominently, CROSSLINK PBI exhibits a stable Coulombic efficiency of more than 99% over 100 charge-discharge cycles at 0.5 C, which is superior to the value of cells using commercial PE and PP (Celgard 2400) separators. The half cells assembled using the CROSSLINK PBI separator can deliver a discharge capacity of 150.3 mAh g-1 at 0.2 C after 50 cycles corresponding to 88.4% of the theoretical value of LiFePO4 (170 mAh g-1). This work offers a worthwhile method to produce thermally stable separators with noteworthy electrochemical performances which opens new possibilities to improve the safe operation of batteries.

Realizing Stable Carbonate Electrolytes in Li–O2/CO2 Batteries†

Comprehensive SummaryThe increasing demand for high‐energy storage systems has propelled the development of Li‐air batteries and Li‐O2/CO2 batteries to elucidate the mechanism and extend battery life. However, the high charge voltage of Li2CO3 accelerates the decomposition of traditional sulfone and ether electrolytes, thus adopting high‐voltage electrolytes in Li‐O2/CO2 batteries is vital to achieve a stable battery system. Herein, we adopt a commercial carbonate electrolyte to prove its excellent suitability in Li‐O2/CO2 batteries. The generated superoxide can be captured by CO2 to form less aggressive intermediates, stabilizing the carbonate electrolyte without reactive oxygen species induced decomposition. In addition, this electrolyte permits the Li metal plating/stripping with a significantly improved reversibility, enabling the possibility of using ultra‐thin Li anode. Benefiting from the good rechargeability of Li2CO3, less cathode passivation, and stabilized Li anode in carbonate electrolyte, the Li‐O2/CO2 battery demonstrates a long cycling lifetime of 167 cycles at 0.1 mA·cm–2 and 0.25 mAh·cm–2. This work paves a new avenue for optimizing carbonate‐based electrolytes for Li‐O2 and Li‐O2/CO2 batteries.

High rate and long-term cycling of silicon anodes with phosphonium-based ionic liquids as electrolytes for lithium-ion batteries

This paper describes the effects of the length of the phosphonium alkyl chain in FSI-based ionic liquids (ILs) used as an electrolyte solvent with Si electrodes in a Li/Si half-cell. The electrochemical performance of Si nanoparticles at a high rate in the synthesized triethyl-n-butylphosphonium bis(fluorosulfonyl)imide) [P2224][FSI] and triethyl-n-octylphosphonium bis(fluorosulfonyl)imide) [P2228][FSI] ILs, which also contain 1 M LiFSI, is compared with that of a common organic electrolyte using either polyacrylic acid (PAA) or polyacrylonitrile (PAN) as a binder. For the three electrolytes, the highest performance was obtained with the PAN binder, while both electrodes in ILs exhibited superior performance compared to the conventional organic electrolyte. For the Si/PAN composite electrode, after 1000 cycles at 1 A.g−1, the delithiation capacities were 1344, 550 and 136 mAh.g−1 for [P2224][FSI] in 1 M LiFSI, [P2228][FSI] in 1 M LiFSI and the commercial organic electrolyte, which corresponded to capacity retentions of 61%, 50% and 5%, respectively. Our results indicate that the chemical structure of the phosphonium cation enabled the tuning of transport properties and significantly influences the electrochemical behavior of the Si anode in the presence of LiFSI/IL as an electrolyte.

Recycling and characterization of end-of-life solid oxide fuel/electrolyzer ceramic material cell components

In this work, a strategy for recycling and recovery of anode supported Solid Oxide Fuel Cell (SOFC) ceramic components is presented. From commercial cells, electrodes and electrolyte are separated by mechanical scraping and grinding, followed by thermal and chemical treatments. Air electrode (LaxSr1-xCoO3), nickel oxide (NiO), which accounts for about 50% of the cell weight, and yttria-stabilized zirconia (YSZ), which is coming from both the fuel electrode and the electrolyte, were successfully separated, and 90–92% of the total weight of initial Ni and YSZ can be collected. The recovered materials are characterized by X-ray diffraction, scanning electron microscopy, (thermal, chemical) analysis and BET surface area measurement, and impurities amounts never excess 1 At.%. The conductivity level of the recycled YSZ materials was measured in air by electrochemical impedance spectroscopy and is found comparable with commercial YSZ material, with a total value exceeding 6.4 10−3 S cm−1 at 700 °C. The contributions of grain and grain boundary conductivities to the total conductivity are clearly distinguishable at lower temperatures.

Thiol-ene crosslinked cellulose-based gel polymer electrolyte with good structural integrity for high cycling performance lithium-metal battery

Gel polymer electrolytes (GPEs) are considered to be one most promising alternative to liquid electrolytes due to their suitability for creating safe and durable solid-state lithium-metal batteries. However, the mechanical properties of GPEs usually deteriorate dramatically when polymer matrices are plasticized by a liquid electrolyte, which leads to significant loss of battery performance. Therefore, the long-term structural integrity and good mechanical strength are critical characteristics of GPEs designed for high-performance batteries. Here, an ecologically compatible cellulose-based GPE with a crosslinked structure is synthesized via a facile and effective thiol-ene click chemistry method. The prepared thiol-ene crosslinked GPE possesses enhanced mechanical strength (10.95 MPa) and rigid structure, which enabled us to fabricate LiFePO4|Li batteries with ultra-long cycling performance. The capacity retention of the crosslinked cellulose-based GPE can be up to 84% at 0.5 C, even after 350 cycles, which is considerably higher than that of non-crosslinked GPE for which rapid decline in capacity occurs after 200 cycles. In addition, a GPE preparation method described in this work compares favorably well with existing commercial electrolytes for lithium metal batteries.

Aqueous sodium ion hybrid batteries with ultra-long cycle life at -50 ℃

• Nonflammable formamide is used as cosolvent to lower the freezing point of ASIBs electrolyte with a high ionic conductivity of 1.75 mS cm−1 at -50°C. • Theoretical calculations and spectroscopic methods reveal that formamide has sufficient active sites to coordinate with water molecules. • The assembled full ASIHBs displayes a super-stable cycling life of 8000 cycles under 4 C at -50°C. • Smart phone and LED bulbs can be power by AHSIBs at -50°C. Aqueous electrolytes are considered as appealing alternatives for commercial organic electrolytes due to their unique merits, such as inherent safety, low cost and environmental friendliness. Unfortunately, they normally cannot operate under extremely low temperature conditions because of the relatively high freezing point of common aqueous electrolytes. To expand their application spaces, the strong polar solvent formamide (FA) is firstly used as a cosolvent for the widely used 17 m NaClO 4 electrolyte (m: mol kg −1 ) in this work. The lowest freezing point of the optimized electrolyte has been significantly reduced below -50°C. Theoretical calculations and spectroscopic methods reveal that FA has sufficient active sites to coordinate with water molecules, cuts off their direct connections and prevents them from forming long-range order structures under subzero temperatures. When paired with the optimized low-temperature electrolyte, the aqueous sodium ion hybrid batteries (ASIHBs) based on active carbon cathode and organic polymer anode deliver a high capacity of ∼80 mAh g −1 at 1 C (1 C = 150 mA g −1 ) and 8000 cycles lifespan at 4 C under -50°C. Encouragingly, the pouch batteries can recharge smart phone for potential application. This electrolyte-modification strategy opens a new avenue to explore superior electrochemical performance for ultra-low temperature ASIHBs.

In-situ constructing “ceramer” electrolytes with robust-flexible interfaces enabling long-cycling lithium metal batteries

² Novel “ceramer” electrolyte with robust-flexible interfaces is in-situ synthesized ² Ceramer electrolyte enables the dendrite-free stripping/plating cycle of Li metal ² Li/Li cells stably cycle over 3600 h at 0.5 mA cm −2 with a constant overpotential ² LFP/Li cells maintain high capacity retention of up to 90.3% at 1C after 500 cycles ² NCM811/Li cell stably cycles for up to 600 cycles at 1C with a high capacity The lifetime and safety of lithium metal batteries (LMBs) with commercial polyolefin separators and liquid electrolytes are deteriorated by the lithium dendrites, as well as leakage and combustion of liquid electrolytes. To effectively address these issues, a “ceramer” electrolyte is in-situ synthesized to exquisitely combine meritorious properties of both cera mic silica (e.g. high modulus) and poly mer poly-1,3-dioxolane (e.g. flexibility/good interface with electrodes), leading to excellent performance for the LMBs. The lithium anodes with the novel “ceramer” electrolyte exhibit ultra-long cycle life and lithium dendrite-free property that is confirmed by in-situ optical microscope. The Li/Li symmetric cells stably plat and strip for up to 3,600 h at 0.5 mA cm −2 with a constant low overpotential. The LiFePO 4 /Li cells present up to 90.3% capacity retention and 99.9 % coulombic efficiency at 1 C after 500 cycles. Even at a higher current density of 2 C, the cell performs an excellent long-term cycle stability with a capacity decay of only 0.0285% per cycle. More significantly, the assembled coin cells (LiNi 0.8 Co 0.1 Mn 0.1 O 2 /Li) delivers high capacity retention of 80.2% at 1 C after 500 cycles, and the pouch cell with high cathode loading (10 mg cm −2 ) and thin lithium anode (∼50 µm) is operated stably. This research provides a very promising strategy to construct a unique organic-inorganic electrolyte with excellent comprehensive properties effectively enabling long-cycle and high-safety LMBs. A “ceramer” electrolyte is in-situ synthesized to exquisitely combine meritorious properties of both ceramic silica and polymer poly-1,3-dioxolane, leading to excellent comprehensive performance for the lithium metal batteries.

Drastically enhancing the cycle stability of copper-dicarboxylate as an anode material for lithium-ion batteries by rational fluorination

Metal-organic frameworks (MOFs) are extensively investigated in lithium-ion batteries because of their large specific surface area, adjustable chemical properties, porous structure, and rich reaction sites. However, the severe capacity attenuation of MOF electrodes has been one of the hardest obstacles hindering the further application of MOFs, due to the embedding and de-embedding of lithium ions during the cycles leading to the structural disintegration and volume fluctuation. Inspired by the wide application of fluorinated additives in commercial electrolytes, a typical carboxylate MOF, copper 1,4-benzenedicarboxylate is fluorinated molecularly to improve its cycle stability. Without enough fluorine source for a robust SEI film, the performance of fluorine-free copper 1,4-benzenedicarboxylate degrades rapidly to 99.5 mAh/g in the initial 21 cycles at a current density of 100 mA g−1, while its fluorinated counterpart, copper tetrafluoroterephthalate, delivers drastically enhanced cycle stability and maintains a reversible specific capacity of 575.5 mAh/g after 500 cycles, due to the SEI-promoting effect of fluorine in the framework. The present fluorination strategy is proved effective and can be extended in much wider applications of MOF materials.

An in-situ formed bifunctional layer for suppressing Li dendrite growth and stabilizing the solid electrolyte interphase layer of anode free lithium metal batteries

Anode-free lithium metal batteries (AFLMBs) can achieve a high energy density. However, achieving high-capacity retention and Coulombic efficiency (CE) are challenging without a continuous Li supply from the Cu anode side. The lower CE and rapid capacity decay in AFLMBs are primarily due to non-uniform Li deposition and electrolyte decomposition during cycling. Herein, strontium fluoride (SrF2) nanoparticles are applied on Cu foils to attain the in-situ forming of a bifunctional interfacial layer, a Li-Sr alloy, and a LiF-rich SEI composite layer during Li plating. The derived Cu@SrF2 electrode has excellent plating/stripping stability and outstanding performance. AFLMB full cell (Cu@SrF2//NCM111) attains an average Coulombic efficiency (ACE) of 98.6 % and capacity retention of 51.0 % at the 60th cycle using a commercial carbonate-based electrolyte. In contrast, the bare AFLMB full cell (BCu//NCM111) only has an ACE of 94.9 % with a capacity retention of 10.2 % under the same conditions. The concept is proven in lithium metal batteries (LMBs). This strategy provides a simultaneous Li nucleation and formation of LiF-rich SEI layers, rendering it promising to realize AFLMBs and LMBs with long lifespans and high CE.

Using Triallyl Phosphate as Electrolyte Additive to Stabilize Electrode–Electrolyte Interface of LiNi0.5Mn1.5O4/Graphite High Voltage Lithium Ion Cells

Using high voltage cathode materials is one of the main ways to improve energy density of Li ion batteries. However, the oxidation of commercial carbonate electrolyte on the cathode makes the batteries suffer serious capacity degradation. In this work triallyl phosphate (TAP) as an electrolyte additive is used to improve the cycle life of LiNi0.5Mn1.5O4 (LNMO)/graphite high voltage lithium ion cell. 1.0 wt % TAP has the best effect; it increases the retention rate of discharge capacity of the cell by about 20% compared with that without additive after 150 cycles at 0.2C. The results of electrochemical measurements, several spectral analyses, and theoretical calculation show that TAP can be electrochemically oxidized prior to the solvents EC and EMC and quickly forms a low molecular weight polymer deposit layer on the cathode, which can effectively prevent electrolyte oxidation and LNMO dissolution. In the absence of interference from electrolyte oxidation products, a dense SEI layer can be formed on the graphite anode whether TAP exists or not. Therefore, although TAP can also be electrochemically reduced to change the composition of the anode SEI layer, the improvement of the cycling performance of LNMO/graphite cell should be attributed to the oxidation reaction of TAP on the cathode.

Two-steps electrochemical polishing of laser powder bed fusion 316l stainless steel

Laser Powder Bed Fusion fabricated 316L stainless steel test components were electrochemically polished in a non-aqueous electrolytic solution consisting of 1M sodium chloride, ethylene glycol, and 10% ethanol, and in an aqueous commercial electrolyte A2. The influence of the high current densities ranging between 250 and 2000 mA/cm2 on the surface roughness (Psa, Wsa and Ssa), materials removal weight and thickness reduction with various morphological characteristics were investigated. It is confirmed that polishing at the tranpassive region was feasible in non-aqueous electrolytes where little pitting occurred. A two-step electrochemical process was proposed based on the characterisations to enhance the polishing effect, which consisted of two processes with different electrolytes and current densities. The experimental results indicated that the surface roughness of two-step polished steels with 1500 and 250 mA/cm2 current densities was reduced by 11.25% than the optimum result of the one-step EP with the non-aqueous electrolyte solution. The weight and thickness reduction were reduced by 3.39% and 9.02%, respectively, more than the optimum results of the one-step EP with the aqueous commercial electrolyte.

Performance Evaluation of An Electrolyte-Supported Intermediate-Temperature Solid Oxide Fuel Cell (IT-SOFC) with Low-Cost Materials

Intermediate temperature solid oxide fuel cell (IT-SOFC) provides economic and technical advantages over the conventional SOFC because of the wider material use, lower fabrication cost and longer lifetime of the cell components. In this work, we fabricated electrolyte-supported IT-SOFC using low-cost materials such as calcia-stabilized zirconia (CSZ) electrolyte fabricated by dry-pressing, NiO-CSZ anode and Ca3Co1.9Zn0.1O6 (CCZO) cathode produced through brush coating technique. According to the XRD result, the monoclinic phase dominated over the cubic phase, and the relative density of the electrolyte was low but the hardness of the CSZ electrolyte was close to the hardness of commercial 8YSZ electrolyte. The performance of the single cell was performed with hydrogen ambient air. An open-circuit voltage (OCV) of 0.43, 0.46, and 0.45 V and a maximum power density of 0.14, 0.50, and 1.00 mW/cm2 were achieved at the operating temperature of 600, 700, and 800 °C, respectively. The ohmic resistance of the cell at 700 and 800 °C achieved 81.5 and 33.00 Ω, respectively due to the contribution of thick electrolyte and Cr poisoning in electrodes and electrolyte