Organic Electrolyte Research Articles

Enabling Uniform and Accurate Control of Cycling Pressure for All‐Solid‐State Batteries

AbstractAll‐solid‐state batteries are emerging as potential successors in energy storage technologies due to their increased safety, stemming from replacing organic liquid electrolytes in conventional Li‐ion batteries with less flammable solid‐state electrolytes. However, all‐solid‐state batteries require precise control over cycling pressure to maintain effective interfacial contacts between materials. Traditional uniaxial cell holders, often used in battery research, face challenges in accommodating electrode volume changes, providing uniform pressure distribution, and maintaining consistent pressure over time. This study introduces isostatic pouch cell holders utilizing air as pressurizing media to achieve uniform and accurately regulated cycling pressure. LiNi0.8Co0.1Mn0.1O2 | Li6PS5Cl | Si pouch cells are fabricated and tested under 1 to 5 MPa pressures, revealing improved electrochemical performance with higher cycling pressures, with 2 MPa as the minimum for optimal operation. A bilayer pouch cell with a theoretical capacity of 100 mAh, cycled with an isostatic pouch cell holder, demonstrated a first‐cycle Coulombic efficiency of 76.9% and a discharge capacity of 173.6 mAh g−1 (88.1 mAh), maintaining 83.6% capacity after 100 cycles. These findings underscore the effectiveness of isostatic pouch cell holders in enhancing the performance and practical application of all‐solid‐state batteries.

Freestanding Ammonium Vanadate Composite Cathodes with Lattice Self-Regulation and Ion Exchange for Long-Lasting Ca-Ion Batteries.

Calcium-ion batteries (CIBs) have emerged as a promising alternative for electrochemical energy storage. The lack of high-performance cathode materials severely limits the development of CIBs. Vanadium oxides are particularly attractive as cathode materials for CIBs, and preinsertion chemistry is often used to improve their calcium storage performance. However, the room temperature cycling lifespan of vanadium oxides in organic electrolytes still falls short of 1000 cycles. Here, based on preinsertion chemistry, the cycling life of vanadium oxides is further improved by integrated electrode and electrolyte engineering. Utilizing a tailored Ca electrolyte, the constructed freestanding (NH4)2V6O16·1.35H2O@graphene oxide@carbon nanotube (NHVO-H@GO@CNT) composite cathode achieves a 305 mAh g-1 high capacity and 10000 cycles record-long life. Additionally, for the first time, a Ca-ion hybrid capacitor full cell is assembled and delivers a capacity of 62.8 mAh g-1. The calcium storage mechanism of NHVO-H@GO@CNT based on a two-phase reaction and the exchange of NH4 + and Ca2+ during cycling are revealed. The lattice self-regulation of V─O layers is observed and the layered vanadium oxides with Ca2+ pillars formed by ion exchange exhibit higher capacity. This work provides novel strategies to enhance the calcium storage performance of vanadium oxides via integrated structural design of electrodes and electrolyte modification.

A Physics-based Model Assisted by Machine-Learning for Sodium-ion Batteries with both Liquid and Solid Electrolytes

Abstract In the absence of experimental data of a fully developed hierarchical 3D sodium solid state batteries, we developed an improved continuum model by relying on Machine Learning-assisted parameter fitting to uncover the intrinsic material properties that can be transferred into different battery models. The electrochemical system simulated has sodium metal P2-type Na2/3[Ni1/3Fe1/12Mn7/12]O2 (NNFMO) as the cathode, paired with two types of electrolytes have been modeled viz, the organic liquid electrolyte and a solid polymer electrolyte. We implemented a 1D continuum model in COMSOL to suit both liquid and solid electrolytes, then used a Gaussian Process Regressor to fit and evaluate the electrochemical parameters in both battery systems. To enhance the generalizability of our model, the liquid cell and solid cell models share the same OCV input for the cathode materials. The resulting parameters are well aligned with their physical meaning and literature values. The continuum model is then used to understand the effect of increasing the thickness of the cathode and current density by analysing the cathode utilization, and the overpotentials arising from transport and charge transfer. This 1D model and the parameter set are ready to be used in a 3D battery architecture design.

Hybrid Ceramic Polymer Electrolytes Enabling Long Cycling in Practical 1 Ah‐Class High‐Voltage Solid‐State Batteries with Li Metal Anode

AbstractSolid polymer electrolytes offer a safer alternative to organic liquid electrolytes in high‐voltage lithium metal batteries, yet challenges remain in achieving adequate cyclability, energy density, scalability, and safety. This study presents the cycling performance of 1 Ah high‐voltage lithium polymer batteries featuring a hybrid ceramic polymer electrolyte (HCPE), a lithium metal anode, and a LiNi0.8Mn0.1Co0.1O2 (NMC‐811)‐based positive electrode. The HCPE stands out for its remarkable mechanical properties, with a Young's modulus exceeding 200 MPa at room temperature, providing robust resistance against dendrite formation. The Li||Li symmetric cells exhibited outstanding performance, cycling for over 1000 hours at a capacity of 2 mAh cm−2, highlighting the exceptional attributes of HCPE. Full cell testing is conducted under practical conditions, utilizing various cell configurations, from coin cells to large pouch cells with a 1 Ah capacity, achieving an energy density of nearly 250 Wh kg−1 and promising cyclability with 80% capacity retention after 110 cycles. The study also investigated thermal runaway characteristics, showing comparability with commercial lithium‐ion batteries. This research underscores the scalability and performance of high‐voltage lithium metal polymer batteries, advancing their potential for commercial viability.

Unleashing Ultrahigh Capacity and Lasting Stability: Aqueous Zinc‐Sulfur Batteries

AbstractDespite of multifarious dominance of sulfur‐based batteries, polysulfide‐shuttling and use of high‐cost organic electrolytes with flammability risks hinder their applicability as commercial devices. Herein a polysulfide‐free aqueous zinc‐sulfur (Zn─S) rechargeable battery is explored, which offers a low‐cost and environmentally friendly energy storage system being Zn and Sulfur (S) highly abundant with high theoretical capacity. However, the stability of Zn anode is quite challenging due to dendritic growth and corrosion leading to the capacity decay. This work showcases the utilization of ethylene glycol (EG) and iodine (I2) as an electrolyte additive in aqueous zinc acetate [Zn(OAc)2] electrolyte for stabilizing the Zn─S battery performance. EG as an additive is able to mitigate the corrosion rate of the Zn electrode by 15 times which is supported by molecular dynamics simulation. The assembled Zn─S battery delivered an outstanding capacity of 1210 mA h g−1 at 0.1 C with a 91% capacity retention even after 250 cycles, along with remarkable reversible prolonged cycling stability of 3000 cycles at 1 C, with 64.5% capacity retention. More importantly, in situ electrochemical Raman spectroscopy is utilized to monitor the real‐time formation of zinc sulfide (ZnS) as a single discharge product and simultaneously debunking the polysulfide shuttling in the system which is further supported by XPS, UV‐Vis and IR spectroscopy.

From Bulk to Interface: Solvent Exchange Dynamics and Their Role in Ion Transport and the Interfacial Model of Rechargeable Magnesium Batteries.

Multivalent battery chemistries have been explored in response to the increasing demand for high-energy rechargeable batteries utilizing sustainable resources. Solvation structures of working cations have been recognized as a key component in the design of electrolytes; however, most structure-property correlations of metal ions in organic electrolytes usually build upon favorable static solvation structures, often overlooking solvent exchange dynamics. We here report the ion solvation structures and solvent exchange rates of magnesium electrolytes in various solvents by using multimodal nuclear magnetic resonance (NMR) analysis and molecular dynamics/density functional theory (MD/DFT) calculations. These magnesium solvation structures and solvent exchange dynamics are correlated to the combined effects of several physicochemical properties of the solvents. Moreover, Mg2+ transport and interfacial charge transfer efficiency are found to be closely correlated to the solvent exchange rate in the binary electrolytes where the solvent exchange is tunable by the fraction of diluent solvents. Our primary findings are (1) most battery-related solvents undergo ultraslow solvent exchange coordinating to Mg2+ (with time scales ranging from 0.5 μs to 5 ms), (2) the cation transport mechanism is a mixture of vehicular and structural diffusion even at the ultraslow exchange limit (with faster solvent exchange leading to faster cation transport), and (3) an interfacial model wherein organic-rich regions facilitate desolvation and inorganic regions promote Mg2+ transport is consistent with our NMR, electrochemistry, and cryogenic X-ray photoelectron spectroscopy (cryo-XPS) results. This observed ultraslow solvent exchange and its importance for ion transport and interfacial properties necessitate the judicious selection of solvents and informed design of electrolyte blends for multivalent electrolytes.

A Cu/MnOx Composite with Copper-Doping-Induced Oxygen Vacancies as a Cathode for Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries are anticipated to be the next generation of important energy storage devices to replace lithium-ion batteries due to the ongoing use of lithium resources and the safety hazards associated with organic electrolytes in lithium-ion batteries. Manganese-based compounds, including MnOx materials, have prominent places among the many zinc-ion battery cathode materials. Additionally, Cu doping can cause the creation of an oxygen vacancy, which increases the material's internal electric field and enhances cycle stability. MnOx also has great cyclic stability and promotes ion transport. At a current density of 0.2 A g-1, the Cu/MnOx nanocomposite obtained a high specific capacitance of 304.4 mAh g-1. In addition, Cu/MnOx nanocomposites showed A high specific capacity of 198.9 mAh g-1 after 1000 cycles at a current density of 0.5 A g-1. Therefore, Cu/MnOx nanocomposites are expected to be a strong contender for the next generation of zinc-ion battery cathode materials in high energy density storage systems.

In situ high‐quality LiF/Li3N inorganic and phenyl‐based organic solid electrolyte interphases for advanced lithium–oxygen batteries

AbstractLithium metal shows a great advantage as the most promising anode for its unparalleled theoretical specific capacity and extremely low electrochemical potential. However, uncontrolled lithium dendrite growth and severe side reactions of the reactive intermediates and organic electrolytes still limit the broad application of lithium metal batteries. Herein, we propose 4‐nitrobenzenesulfonyl fluoride (NBSF) as an electrolyte additive for forming a stable organic–inorganic hybrid solid electrolyte interphase (SEI) layer on the lithium surface. The abundance of lithium fluoride and lithium nitride can guarantee the SEI layer's toughness and high ionic conductivity, achieving dendrite‐free lithium deposition. Meanwhile, the phenyl group of NBSF significantly contributes to both the chemical stability of the SEI layer and the good adaptation to volume changes of the lithium anode. The lithium–oxygen batteries with NBSF exhibit prolonged cycle lives and excellent cycling stability. This simple approach is hoped to improve the development of the organic–inorganic SEI layer to stabilize the lithium anodes for lithium–oxygen batteries.

High-performance Bipolar Membrane for CO2 Electro-reduction to CO in Organic Electrolyte with NaOH and Cl2 Produced as Byproducts

Bipolar membranes (BPM) are a special class of ion-exchange membranes constituted by a cation- and an anion-exchange layer, allowing the generation of protons and hydroxide ions via water dissociation. This unique feature makes them useful in a wide range of application. In this work, we have fabricated a novel BPM, with SnO2 hollow spheres used as water dissociation catalyst. Such fabricated BPM has been served as a diaphragm to construct a three-chamber electrolyzer for CO2 electro-reduction to CO in organic electrolyte. During the long-term electrolysis process, the cathodic current density has reached to ∼96.5 mA·cm-2, with the Faraday efficiency of CO stabled at ∼92.6%. Compared with widely used commercial BPM, as-prepared BPM exhibited many advantages, such as lower hydrolysis over-potential, high catalytic efficiency and low total resistance. This technology extends the prospect of BPM application in the field of CO2 reduction.

Heavily vanadium-doped LiFePO4 olivine as electrode material for Li-ion aqueous rechargeable batteries

Since LiFePO4 batteries play a major role in the transition to safe, more affordable and sustainable energy production, numerous strategies have been applied to modify LFP cathode, with the aim of improving its electrochemistry. In this contribution, a highly vanadium-doped LiFe0.9V0.1PO4/C composite (LFP/C-10V) is synthesized using the glycine combustion method and characterized by x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetry Differential Thermal Analysis (TGDTA) and Cyclic Voltammetry (CV). It is shown that 10wt.% of vanadium can substitute Fe positions, thus decreasing unit cell volume, which is followed by generation of Li3V2PO4 traces, as detected by CV. High vanadium doping does not change the carbon content in the composite (≈13 wt%) but improves its electronic conductivity and electrochemical performance in both aqueous and organic electrolytes. The reversibility and current response are increasing following the trend: LFP/C, LFP/C -3mol%V, LFP/C - 5 mol % and LFP/C-10 mol %. The best specific capacity is obtained for the most highly doped olivine, which exhibits a reversible process at 1 mV s−1 in an aqueous electrolyte, thus showing a peak-to-peak distance of 56 mV. The high capacity of LFPC-10V is measured in both LiNO3 and NaNO3 electrolytes amounting to around 100 mAh g−1 at 20 mV s−1. Still, the material is only stable in LiNO3 electrolyte, making it more suitable for Li than Na-ion aqueous rechargeable batteries.

Full gradient compensation of LiNO3 in the suspension electrolyte for lithium metal batteries

Uncontrolled side reactions between lithium metal and organic electrolytes seriously deteriorates the stability of corresponding battery due to the non-uniform Li+ deposition. Using lithium nitrate (LiNO3) as an additive can adjust the components in solid-electrolyte-interphase (SEI) for optimizing of lithium metal interface. However, the low solubility and rapid consumption of LiNO3 in ester-based electrolytes limit its further application. Herein, a kind of suspension electrolyte containing micron-sized LiNO3 particles is reported to realize a full gradient compensation against the consumption of NO3−. Benefiting from the uniformly dispersion of LiNO3 particles, a SEI layer containing even-distributed Li3N and LiNxOy with high content is constructed that promotes the rapid and uniform plating of Li+. Consequently, the Li/Cu batteries present a polarization of only 15–20 mV, and exhibit a consistent performance for 230 cycles with the CE of 98.1%, which is 4 times than that of conventional carbonate electrolytes. In addition, the cycling life of the assembled Li/NCM811 batteries can be extended to 260 cycles with a high capacity retention of 82.4 %.

Co-doping strategies for advanced solid state electrolytes with lithium salt: a study on the structural and electrochemical properties of LATP

The commercialization of lithium-ion batteries has revolutionized the field of energy storage, yet their usage of organic electrolytes has led to significant safety concerns. Solid-state electrolytes have emerged as a promising solution to these issues, enabling the development of high-performance solid-state lithium batteries. The NASICON-type solid electrolyte Li1.3Al0.3Ti1.7P3O12 (LATP) has demonstrated excellent properties and significant potential. This study involves the solid-state synthesis of LATP electrolytes doped with Cobalt and Silicon. Furthermore, adding 8% LiBr into LATP-0.04 significantly enhanced ionic conductivity, reaching a value of 3.50 × 10−4 S cm−1. This can be linked to lithium salt filling vacant spaces between grains, resulting in a significant drop in grain boundary resistances. The electrochemical analysis through Linear Sweep Voltammetry (LSV) indicates that the investigated material demonstrates the capability to sustain stability and functionality even under the influence of elevated voltages, notably up to 5.45 V. These findings imply that optimal cobalt doping and Lithium salt contribute to superior ionic conductivity compared to pristine LATP.

A Comparative Review of Models for All-Solid-State Li-Ion Batteries

In recent times, there has been significant enthusiasm for the development of all-solid-state Li-ion batteries. This interest stems from a dual focus on safety—addressing concerns related to toxic and flammable organic liquid electrolytes—and the pursuit of high energy density. While liquid electrolyte batteries currently constitute the vast majority of commercial cells, solid electrolyte batteries show great promise. In parallel with experimental research, computational models clarify several fundamental physics that take place throughout battery operations. Giving up on reviewing a broad screening of the existing literature, we set out to select here a few highly relevant models, emphasizing some fundamental conceptual advancements and offering an in-depth and critical insight into the current state of the art. The papers we selected aim at providing the reader with a tangible and quantitative understanding of how all-solid-state Li-ion batteries operate, including the different mechanisms at play and the mathematical tools required to model the pertinent physics and mechanics.

A Comprehensive Review of Novel Emerging Electrolytes for Supercapacitors: Aqueous and Organic Electrolytes Versus Ionic Liquid-Based Electrolytes

A Comprehensive Review of Novel Emerging Electrolytes for Supercapacitors: Aqueous and Organic Electrolytes Versus Ionic Liquid-Based Electrolytes

Facet engineering of α-MnO2 for directly electrocatalytic oxygen atom transfer from water toward epoxidation

Electrocatalytic epoxidation, utilizing sustainable water and electricity as clean oxygen source and chemical oxidant surrogates respectively, represents an attractive approach toward industrial applications. However, the low yield and selectivity of epoxides are still a formidable challenge in satisfying industrial demand. Herein, we demonstrated a crystal facet engineering strategy over α-MnO2 catalysts for enhancing electrocatalytic epoxidation. Compared with α-MnO2-110 and α-MnO2-100, the α-MnO2 exposed with (310) facet exhibited excellent activity. Furthermore, a 21-fold yield increase was obtained compared with the reported superior Mn-based electrocatalyst. These results revealed that crystal facet engineering could induce the formation of more oxygen vacancies and weaken the interaction of Mn-O band to regulate oxygen atom transfer capacity. In addition, the reactive intermediate (MnOOH) was observed in an organic electrolyte, which was confirmed by in situ Raman spectra and isotope labeling experiment.

Dual-type confinement strategy: Improving the stability of organic composite cathodes for Lithium-ion batteries with longer lifespan

Inclusive reports on organic cathodes are the key evidence of their superior performance for Lithium-ion batteries. However, it is still promising to simultaneously achieve a higher practical specific capacity and longer cycling life, owing to the crucial concern of the dissolution of active molecules in organic electrolytes. The introduction of porous carbon confinement and coating which can impart discharge capacity and cycling stability, is highly beneficial. Herein, we designed and prepared a novel composite cathode (designated as HKUST-1-C@DHAQ@TiO2) with small molecules (DHAQ) in porous carbon skeleton (HKUST-1-C) as core and TiO2 as shell. The unique dual-type confinement strategy offers short Li+/e- diffusion directions for redox reactions and superior structural stability during cycling without dissolution or decomposition of the components, resulting in excellent electrochemical performance. The HKUST-1-C@DHAQ@TiO2 cathode delivers significant specific capacity (209 mAh g−1, 0.1 A g−1), markable Coulombic efficiency (nearly 100 %), notable cycling stability (86 % retention for provided 200 cycles) and excellent rate capacity (138 mAh g−1 at 1.0 A g−1). The presented findings offer the deep understanding of redox reactions and organic cathode evolution mechanisms for the progress of smarter energy storage batteries.

Effect of Protic and Aprotic Formamide‐Based Organic Electrolytes for Rechargeable Zinc/MnO2 Battery

Zinc ion batteries (ZIBs) are emerging as a promising and cost‐effective alternative energy storage system compared to other metal‐ion batteries. Aqueous electrolytes have been extensively studied in Zn‐ion batteries which has shown issues related to cathode dissolution. In comparison, little has been looked into the use of organic electrolytes in ZIBs. Here, we have studied both protic and aprotic forms of formamide‐based organic electrolytes containing Zn trifluoromethanesulfonate and their influence on the Zn solvation chemistry, electrochemistry, and performance of Zn‐MnO2 battery. It was observed that protic‐based electrolytes gave a much better capacity and stability for the Zn‐MnO2 battery. A capacity close to 150 mAh g‐1 was obtained with formamide electrolyte at a current density of 0.25 A g‐1. For all the other formamide‐based electrolytes tested, the capacity was lower. After 200 cycles, an average capacity retention of 72% was obtained for formamide‐based electrolyte. This study shows that protic‐based electrolytes might be a suitable option for non‐aqueous‐based Zn‐ion batteries.

In Situ Polymerization Inhibiting Electron Localization in Hybrid Electrolyte for Room‐Temperature Solid‐State Lithium Metal Batteries

AbstractHybrid solid electrolytes (HSEs) have attracted much attention due to their advantages as both inorganic and organic polymer electrolytes. However, the organic/inorganic interfacial space charge layer has a great barrier to the transport of Li+ in the HSE. Here, an in situ polymerization layer is proposed on garnet‐type particles, working as the coherent region to eliminate the space charge layer at the organic/inorganic interfaces by inhibiting electron localization. The conjugate hybridization of fillers weakens the aggregation of particles, induces the dissociation of Li salt, and provides high‐throughput Li+ transport pathways at the ceramics/polymer interface. Furthermore, the continuous Li+ conduction networks are connected by the coherent region between inorganic fillers and polymer chains. The fabricated HSE exhibits a high ionic conductivity of 0.47 mS cm−1 and ion migration numbers of 0.78 at room temperature. The 3D Li//Li systematic battery assembled with the HSE delivers a high critical current density (CCD) of 2.0 mA cm−2. Meanwhile, the 4.5 V NCM811//Li batteries achieve a prolonged operation of 500 cycles at 0.5 C. The Li//LiFePO4 batteries demonstrate superior capacity retention of 96.4% at 1 C after 500 cycles.

Cover Picture: Operando Temperature Dynamic Investigation of Electric Double‐Layer Capacitors Containing Organic Electrolytes (Batteries & Supercaps 5/2024)

Cover Picture: Operando Temperature Dynamic Investigation of Electric Double‐Layer Capacitors Containing Organic Electrolytes (Batteries & Supercaps 5/2024)

Operando Temperature Dynamic Investigation of Electric Double‐Layer Capacitors Containing Organic Electrolytes

AbstractInvited for this month's cover picture is the Balducci's group who works on the development of innovative electrolytes and materials for safer, high‐performance supercapacitors and batteries, and on advanced real‐time characterization techniques to improve the understanding of aging and charge storage processes in electrochemical devices. The front cover illustrates a supercapacitor evaluated with the screening technique presented in this report. It highlights different electrolyte compositions, indicated by chemical compounds above the setup. This approach provides insights into how capacitance, energy, power, entropy, and enthalpy respond to changes in temperature and voltage. Read the full text of the Research Article at 10.1002/batt.202300581.