Aqueous Lithium-ion Batteries Research Articles

Advances of LiCoO2 in Cathode of Aqueous Lithium-Ion Batteries.

Aqueous lithium-ion batteries offer promising advantages such as low cost, enhanced safety, high rate capability, and the ability to deliver considerable capacity at 1.8V, making them ideal candidates for large-scale reserve power sources for renewable energy. However, the practical application of aqueous lithium-ion batteries has been hindered by the poor cycle stability of layered cathode materials, including LiCoO2, in neutral aqueous electrolytes. This review examines the working principles, material limitations, and research progress of aqueous lithium-ion batteries. The types and characteristics of materials used in the cathode of aqueous lithium-ion batteries are summarized, with a primary focus on the attenuation mechanisms of LiCoO2 when used as the cathode material in aqueous electrolytes. Furthermore, this review explores the advancements in utilizing LiCoO2 in the cathode of aqueous lithium-ion batteries, as well as the combination with machine learning. By addressing these critical aspects, this review aims to provide a comprehensive understanding of aqueous lithium-ion batteries and shed light on future development and application prospects.

Interfacial Chemistry in Aqueous Lithium-Ion Batteries: A Case Study of V2O5 in Dilute Aqueous Electrolytes.

Aqueous lithium-ion batteries (ALIBs) are promising for large-scale energy storage systems because of the cost-effective, intrinsically safe, and environmentally friendly properties of aqueous electrolytes. Practical application is however impeded by interfacial side-reactions and the narrow electrochemical stability window (ESW) of aqueous electrolytes. Even though higher electrolyte salt concentrations (e.g., water-in-salt electrolyte) enhance performance by widening the ESW, the nature and extent of side-reaction processes are debated and more fundamental understanding thereof is needed. Herein, the interfacial chemistry of one of the most popular electrode materials, V2O5, for aqueous batteries is systematically explored by a unique set of operando analytical techniques. By monitoring electrode/electrolyte interphase deposition, electrolyte pH, and gas evolution, the highly dynamic formation/dissolution of V2O5/V2O4, Li2CO3 and LiF during dis-/charge is demonstrated and shown to be coupled with electrolyte decomposition and conductive carbon oxidation, regardless of electrolyte salt concentration. The study provides deeper understanding of interfacial chemistry of active materials under variable proton activity in aqueous electrolytes, hence guiding the design of more effective electrode/electrolyte interfaces for ALIBs and beyond.

Low-Cost and Sustainable Aqueous Lithium-Ion Batteries by All-Organic PTCDI Anodes

Electrolyte engineering has been key to the advancement of aqueous lithium-ion batteries (ALIBs), for example, the introduction of water-in-salt electrolytes (WiSEs) has enabled ALIBs to cycle well and to operate at potentials far beyond the electrochemical stability window of water. WiSEs are, however, intrinsically based on high concentrations of salt(s) which furthermore often are expensive and fluorinated, and therefore defeats the aim of ALIBs being low-cost and sustainable. Strategies to circumvent this issue have been to add co-solvents and/or diluents to decrease the overall electrolyte concentration or customize the anion and salt concentration to each battery chemistry. The clean and green ethos of ALIBs can be enhanced by using organic active materials (AMs), but these are unfortunately often water soluble and therefore requires an electrolyte designed to mitigate dissolution/electrode de-attachment.Herein, we for the first time implement perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) as the anode AM for ALIBs. We demonstrate that by appropriate aqueous electrolyte selection we can truly mitigate electrode de-attachment, leading to excellent properties in terms of capacity, rate capability, cycling stability, and Coulombic efficiency. All things considered, this endeavour intends to further reduce the kWh/€ and thereby reinforcing the feasibility of more cost-effective large-scale battery energy storage solutions Fig 1. Long term galvanostatic cycling of an all-organic PTCDI electrode in a PTCDI/low conc. aqueous el./LFP cell set-up. Inset shows the chemical structure of PTCDI and the corresponding charge/discharge voltage curves. Figure 1

Interfacial Chemistry in Aqueous Lithium-Ion Batteries with Dilute Aqueous Electrolytes: A Case Study with V2O5

Aqueous lithium ion batteries (ALIBs) are promising candidates for large-scale energy storage systems, benefiting from the intrinsic safe and environmentally friendly properties of aqueous electrolytes. However, its practical application is impeded due to the narrow electrochemical stability windows (ESWs) of aqueous electrolytes. Despite that increasing electrolyte concentration can achieve a wide ESW with the protection of SEI layer, it brings numerous disadvantages induced by excessive salt as well. Therefore, understanding the SEI formation mechanism and further widening the ESWs of dilute aqueous electrolytes are critical for the breakthrough of next-generation ALIBs.Herein, the interphase chemistry of V2O5 electrode with dilute aqueous electrolyte was systematic investigated by conducting various Operando characterizations with LMO||V2O5 cell system. Dynamic SEI, which consists of Li2CO3, LiF and V2O4, was formed during charge and disappeared during the following discharge, which is strongly affected by electrolyte pH fluctuation. Moreover, its evolution process is reversible during cycling. There are several impacts affect the pH fluctuation during cycling. First, V2O5 dissolution, which turns electrolyte into acidic before cycling, and is aggravated by electrolyte concentration decrease. Second, proton/hydronium ion insertion, which takes place on electrode surface in dilute electrolyte, while it is suppressed by concentration increase due to reduced proton concentration. Third, the redox reaction of dissolved V2O5, which is controlled by both potential and electrolyte pH change according to the V-H2O poubaix diagram. Along with the anode potential decrease and the alkalinisation of electrolyte, V2O4 is formed on anode surface by the reduction of HV10O28 5- and V4O12 4- and this reduction process further produces hydroxide ion into electrolyte. Last, the carbon oxidation, which takes place on cathode side during charge and on anode side during the final discharge. Therefore, the acidification of electrolyte during cycling is detrimental to SEI stability in aqueous electrolytes. This systematic research work provides new perspectives to the understanding of the interphase chemistry evolution in aqueous Li-ion batteries using dilute electrolytes, which guides the building of effective SEI layer in aqueous Li-ion batteries and beyond. Figure 1

Stable Ammonium-Ion Batteries in Diluted Electrolyte By Manipulation of H-Bonding Network Via Ethylene Glycol

Aqueous rechargeable batteries (ARB) arose considerable interest for stationary energy storage due to low cost, inherent safety, and environmental friendliness.[1] Besides aqueous lithium-ion batteries, various kinds of aqueous batteries have been proposed, utilizing relatively inexpensive charge carriers either based on metal (Na+, K+, Ca2+, Mg2+, Zn2+, Al3+, etc.) or non-metal cations (H3O+, NH4 + etc.).[2] Among non-metallic ion batteries, aqueous ammonium-ion batteries (AAIBs) distinguish themselves by working in near neutral or mild acidic environment, refraining from severe electrode corrosion.[3] However, like other ARB systems, the energy density of AAIBs is limited by the narrow electrochemical stability window of the aqueous electrolyte. In addition, NH4 + ions hydrolyse in water resulting in decreased pH of the electrolyte which promotes the hydrogen evolution reaction (HER).[3] This means that increasing salt concentration may not be an effective strategy to enlarge the stability window of the electrolyte. In fact, according to a previous report, the cathodic stability of 25 m ammonium acetate (NH4Ac) is even slightly inferior than that of 1 M NH4Ac.[4] Developing alternative strategies to inhibit HER in diluted electrolytes is of uttermost importance.In diluted aqueous electrolytes, the continuous and complicated H bond network among water molecules favours fast ionic motion but also causes severe HER. Here, we propose ethylene glycol (EG) as electrolyte component to manipulate the H bond structure in diluted (1 m) NH4Ac solutions. FTIR results are used to study the H-bonding network as function of the EG:water ratio. The diluted aqueous electrolyte containing EG show no freezing point and wider electrochemical window. As a proof-of-concept, full cells composed of Prussian blue derivatives, PTCDI anode, and 1 m NH4Ac with the addition of EG are tested to verify the effectiveness of EG during battery operation. Improved cycling performance and higher coulombic efficiencies are demonstrated compared to those including 1 m NH4Ac in water.

Understanding the Super-Theoretical Capacity Behavior of VO2 in Aqueous Zn Batteries.

VO2 material, as a promising intercalation host, is widely investigated not only in aqueous lithium-ion batteries, but also in aqueous zinc-ion batteries (AZIBs) owing to its stable tunnel-like framework and multivalence of vanadium. Different from lithium-ion storage, VO2 can provide higher capacity when storing zinc ions, even exceeding its theoretical capacity (323mAhg-1), but the specific reason for this unconventional performance in AZIBs is still unclear. The present study proposes a catalytic oxygen evolution reaction (OER) coupled with an interface oxidation mechanism of VO2 during the initial charging to a high voltage. This coupling induces a phase transformation of VO2 into a high oxidation state of V5O12∙6H2O, enabling a nearly two-electron reaction and providing additional zinc storage sites to achieve super-theoretical capacity. Furthermore, it is demonstrated that these vanadium oxide cathodes (V2O3, VO2, and V2O5) will all undergo phase change after the first charge or short cycle. Notably, water molecules participate in the final formation of layered vanadium-based hydrate, highlighting their crucial role as "pillars" for stabilizing the structure. This work significantly enhances the understanding of vanadium-based oxide cathodes.

3D Printed Rechargeable Aqueous and Non-Aqueous Lithium-Ion Batteries: Evolution of Design and Performance

Here we describe the modeling and design evolution of vat polimerized (Vat-P) stereolithographic apparatus (SLA) 3D printed coin cell-type aqueous and non-aqueous rechargeable lithium-ion batteries, cases and current collectors. We detail the rationale for design evolution that improved performance, handling and assembly of the printed batteries. Some guidance into the modeling, 3D printing process, material choice, chemical and electrochemical stability, assembly, sealing, and performance of 3D printed Li-ion batteries is outlined. 3D printed Li-ion batteries demonstrated promising results in terms of gravimetric capacity, rate capability, and capacity per unit footprint area compared to conventional coin cells in both aqueous and non-aqueous systems. For aqueous cells, the cell level capacity is a factor of 2–3x higher than similar metal coin cells due to the lighter weight and better rate response. We also outline design requirements for a Vat-P printed battery that are compatible with organic carbonate-based electrolytes, where the cell provides 115 mAh g−1 specific capacity using an LiCoO2–graphite chemistry, which is only ∼20% less than the maximum reversible capacity of LCO. Despite the challenges faced in optimizing the design and materials for 3D printed Li-ion batteries, this study provides valuable information for future research and development.

Passivated Bi2Se3 electrode in Na2CO3 solution to improve anode efficiency in aqueous Li-ion batteries

Efficient anode materials are crucial for the success of aqueous rechargeable lithium-ion batteries (ALIBs) since many materials degrade significantly during electrochemical reactions. In this study, the modification of Bi2Se3 with Na2CO3 was explored to enhance the charge–discharge characteristics of the anode. The passivated Bi2Se3 electrode exhibited improved electrochemical performance, maintaining high charge and discharge capacities of 816 mAh·g−1 after the 5th cycle and 570 mAh·g−1 after the 100th cycle with stable Coulombic efficiency of 98.0 ± 1.2 %. Charge-discharge profiles and cyclic voltammetry revealed the lithium intercalation and deintercalation, while impedance spectroscopy indicated changes in the electrode structure during cycling. These findings highlight the potential of using Bi2Se3 electrodes with a pre-formed surface film to enhance the stability and performance of ALIBs.

Improved Electrochemical Properties of Aqueous Lithium-Ion Batteries Via the Optimization of Gel Polymer Electrolytes

Lithium-ion batteries (LIBs) have been developed for their high energy density and long cycle life in military systems. However, the use of non-aqueous electrolytes based on toxic and flammable organic solvents have raised serious safety concerns including fire and explosion in LIBs. Aqueous LIBs with non-flammable and environmental aqueous electrolytes are promising alternative to eliminate the safety issues. Because aqueous batteries use water as a solvent of electrolyte, they are stable with no flammable. However, the narrow electrochemical stability window (ESW) of water in aqueous electrolytes limits operating voltage and energy density of aqueous batteries. Recently, ESW was expanded by applying a high concentration lithium salt electrolyte called “water-in-bisalt” (WIBS). A 4.0 V aqueous LIB was developed by passivating graphite anodes with hydrophobic LiTFSI-HFE gels, which effectively extended electrolyte stability [1].In this study, we developed a 4.0 V aqueous LIBs using UV-cured gel polymer electrolytes. Highly concentrated UV-cured gel polymer electrolytes were coated to cathodes and UV-cured gel protection layers were applied to anode surfaces for improving stability. Also, gel polymer electrolytes were optimized with various lithium salts and additives. We also evaluated cycle performance and safety such as cutting, penetration test with LiMn2O4∥graphite pouch type cells. There were no fires and explosions.

Using Pectin for Energy Storage Devices

Wearable and flexible printed electronics are more than ever in demand. The value of the flexible electronics market reached USD 26.5 million in 2021 and its revenue forecast will reach USD 63.1 million in 2030.[1] Increasing investments in research & development in these fields have already led to several achievements in the past years. Nevertheless, serious remains concerns about the ecological footprint of such technologies must be addressed early in their conception and throughout the whole electronics life cycle.[2]In printed electronics, electrical energy is supplied by energy storage devices, such as batteries. Most of the time, these systems contain polymers that can be used either as electrolyte, e.g., solid polymer electrolyte or gel polymer electrolyte, to facilitate flexible electronics/batteries fabrication or as binders in positive or negative electrodes ensuring the mechanical cohesion within the composite electrodes.[4]. Several characteristics to meet environmental-friendly flexible electronics requirements. Biobased polymers are one of the promising alternatives in this regard. Their general affinity with water makes them suitable for aqueous rechargeable batteries, implying several technologies such as aqueous rechargeable lithium-ion batteries (ARLB) or zinc rechargeable batteries (ZRB). For instance, polymer hydrogel electrolytes have recently been investigated [3]: their strength lies in promising ionic conductivity (> 10-2 S.cm-1) while maintaining a sufficient mechanical strength and elasticity to be adaptable to flexible energy storage devices.In this study, we developed a hydrogel electrolyte made of pectin, a polysaccharide contained in the cell plants’ wall, as an alternative to synthetic polymers in batteries. Hydrophobic interactions and hydrogen bonds, together with bivalent cation interactions, allow the free-standing electrolyte gelation.[5] The gelation mechanism is first studied, using NMR spectroscopy together with thermal analysis. Then, electrochemical characterization is carried out to analyze the ionic conduction pathways of the gel electrolyte. Its electrochemical stability as well as galvanostatic cycling are investigated to figure out its ability to be used as a electrolyte in hybrid device, such as zinc-lithium-ion batteries.Moving toward printed devices requires to take a closer look to the rheological properties of this system as well as its printability: these challenges will be addressed to ultimately develop an understanding of the impact of this material’s processing on the electrolyte and electrodes properties.[6] References [1]. Flexible Electronics Market Size to Hit US$ 63.1 MN by 2030. (May 2022). Acumen Research and Consulting, https://www.acumenresearchandconsulting.com/.[2]. Baran, D.; Corzo, D.; Blazquez, G. Flexible Electronics: Status, Challenges and Opportunities. Frontiers in Electronics 2020, 1, 2673-5857. DOI: 10.3389/felec.2020.594003.[3]. Liu, J.; Yuan, H.; Tao, X.; et al. Recent progress on biomass-derived ecomaterials toward advanced rechargeable lithium batteries. EcoMat 2020, 2 (1), e12019. DOI: 10.1002/eom2.12019.[4]. Bresser, D.; Buchholz, D.; Moretti, A.; Varzi, A.; Passerini, S. Alternative binders for sustainable electrochemical energy storage – the transition to aqueous electrode processing and bio-derived polymers. Energy Environm Sci 2018, 11, 3096-3127. DOI: 10.1039/C8EE00640G.[5]. Chelfouh, N.; Coquil, G.; Rousselot, S.; Foran, G.; Briqueleur, E.; Shoghi, F.; Caradant, L.; Dollé, M. Apple Pectin-Based Hydrogel Electrolyte for Energy Storage Applications. ACS Sustainable Chemistry & Engineering 2022 , Article ASAP . DOI: 10.1021/acssuschemeng.2c04600.[6]. Clement, B.; Lyu, M.; Kulkarni, S. E.; Lin, T.; Hu, Y.; Lockett, V.; Greig, C.; Wang, L. Recent Advances in Printed Thin-Film Batteries. Engineering 2022, 13, 238-261. DOI: 10.1016/j.eng.2022.04.002.

An organic composite anode with multiple active points for aqueous lithium-ion batteries

As one of the promising anode materials for lithium ion battery, organic materials are widely regarded. Hence, poly (1,4,5,8-naphthalenetetracarboxylic sulfonyl) imine (PNSI) exhibits promising electrochemical performance as the anode of aqueous lithium-ion batteries (ALIBs) owning to presence of redox CO and SO groups. However, this PNSI has low electronic conductivity, so a significant amount of conducting carbon is required in the preparation of PNSI electrode to achieve good conductivity, which remarkably reduced the specific capacity of the electrode. In this study, a simple in-situ graphene coating method is developed and the obtained PNSI@rGO composite displays significantly improved electrochemical performance. The PNSI wrapped by 20.5% rGO (PNSI@rGO-20.5%) has a specific discharge capacity of 141.8 mAh g−1 after 1000 cycles at 1A g−1 without the addition of a any extra conductive agents. The capacity retention ratio of PNSI@rGO-20.5%||LiMn2O4 full cell assembled with PNSI@rGO-20.5% as anode and LiMn2O4 as cathode is 83.0% after 1000 cycles at 1A g−1. The excellent electrochemical performance of PNSI@rGO-20.5% composite makes it a potential anode material for ALIBs.

Modification of Single-Walled Carbon Nanotube Networks Anodes for Application in Aqueous Lithium-Ion Batteries

The changes in global energy trends and the high demand for secondary power sources, have led to a renewed interest in aqueous lithium-ion batteries. The selection of a suitable anode for aqueous media is a difficult task because many anode materials have poor cycling performance due to side reactions with water or dissolved oxygen. An effective method for improving the characteristics of anodes in aqueous electrolyte solutions is adding carbon nanotubes (CNTs) to the electrode materials. For a better comprehension of the mechanism of energy accumulation and the reasons for the loss of capacity during the cycling of chemical current sources, it is necessary to understand the behaviour of the constituent components of the anodes. Although CNTs are well studied theoretically and experimentally, there is no information about their behaviour in aqueous solutions during the intercalation/deintercalation of lithium ions. This work reveals the mechanism of operation of untreated and annealed single-walled carbon nanotubes (SWCNT) anodes during the intercalation/deintercalation of Li+ from an aqueous 5 M LiNO3 electrolyte. The presence of -COOH groups on the surface of untreated SWCNTs is the reason for the low discharge capacity of the SWCNT anode in 5 M LiNO3 (3 mAh g−1 after 100 cycles). Their performance was improved by annealing in a hydrogen atmosphere, which selectively removed the -COOH groups and increased the discharge capacity of SWCNT by a factor of 10 (33 mAh g−1 after 100 cycles).

Overcrowded Additive in Electrolyte and Crystalline Li2CO3 Artificial Solid Electrolyte Interphase on TiNb2O7 Anode Enable Long Lifespan Aqueous Lithium-Ion Batteries

Aqueous lithium-ion batteries (ALIBs) are attracting intense attention because of the intrinsic nonflammable nature of the aqueous electrolytes. However, its own narrow electrochemical window has led to numerous problems such as dissolution of electrode materials, hydrogen evolution at the anode, and poor cycling stability. Here, we report an “overcrowded electrolyte” using 1,4-dioxane as an additive, which has lone pairs of electrons on the oxygen atom to disrupt the original water-hydrogen bonding network by forming intermolecular hydrogen bonds, thereby inhibiting the hydrogen evolution reaction (HER) and decreasing the water activity. Furthermore, a layer of crystalline Li2CO3 is coated onto the surface of the TiNb2O7 anode material by supercritical fluid CO2 technology. The dense hydrophobic Li2CO3 coating layer can serve as a physical protection, which effectively blocks the direct contact between electrolyte and electrode. Under the synergistic effect of those two aspects, HER is greatly suppressed and the interface stability is enhanced. As a result, LiMn2O4/TiNb2O7 full cells exhibit a high initial coulomb efficiency of 95% with a capacity retention rate of 92% over 500 cycles under 1 C rate. This work provides a fundamental understanding of the interfacial chemistry of ALIBs and makes an important step forward in the development of high-performance and low-cost ALIBs for practical applications.

Enhanced electrochemistry of AlPO4 nano-layer-wrapped LiMn2O4 cathode material for an aqueous rechargeable lithium-ion battery

Enhanced electrochemistry of AlPO4 nano-layer-wrapped LiMn2O4 cathode material for an aqueous rechargeable lithium-ion battery

Nanoflowers-like LiTi2(PO4)3 on carbon nanotube fibers as novel binder-free anodes for high-performance fiber-shaped aqueous rechargeable lithium-ion batteries

NASICON-type LiTi2(PO4)3 (LTP) shows tremendous potential for applications in aqueous rechargeable lithium-ion batteries (ARLIBs) due to its three-dimensional open-framework and flat voltage platform. Unfortunately, conventional solid-phase reactions and high-temperature calcination methods are unable to meet the demand for self-standing electrodes for flexible wearable ARLIBs. Herein, we develop a simple and effective one-step solvothermal method to grow nanoflowers (NFs)-like LTP directly on carbon nanotube fibers (CNTFs) as binder-free anodes for fiber-shaped ARLIBs (FARLIBs) without additional high-temperature treatment. Benefitting from the robust adhesion of the active material to the substrate and binder-free feature, the prepared LTP NFs/CNTF anode provides a high reversible volume capacity of 85.2 mAh cm−3 at a current density of 0.4 A cm−3. The quasi-solid-state FARLIB is successfully assembled by binder-free cathode coupling with LiMn2O4 nanowall arrays directly grown on CNTF, achieving a high capacity of 58.3 mAh cm−3 at a current density of 0.4 A cm−3 and exhibiting an encouraging 92.3 mWh cm−3 maximum energy density. This work provides an effective strategy for the design of novel binder-free electrodes for next-generation wearable FARLIBs.

Nanostructured europium-doped layered lithium manganese oxide as a prospective cathode material for aqueous lithium-ion battery

As the world moves to greener and renewable energy generation technologies, scientific researchers are facing a great challenge of concurrently developing energy storage materials with a low production cost, environmentally benign, high-energy density, and good safety. In this work, we report on the improved cycling and reduced phase transformation of the well-studied n-Li2MnO3 achieved by doping with Europium. It was established from cyclic voltammetry results that Eu-doping had a stabilization effect on the lattice oxygen and further prevented the migration of the manganese ions previously coordinated to the released lattice oxygen, into vacant octahedral site that were occupied by the removed Li+. As such, the new material exhibited an increase in conductivity with cycling and coulombic efficiency increased from ∼74 to ∼88% over 100 cycles. Moreover, the discharge capacity of Li2Mn0.95Eu0.05O3 improved with cycling from 4.20 mAh.g − 1 to 5.47 mAh.g − 1.

Carbon-coated LiTi2(PO4)3 composites synthesized through tannic acid with high rate performance for aqueous lithium-ion batteries

Carbon-coated LiTi2(PO4)3 (LTP-1) was synthesized by sol-gel and in-situ coating method, with tannic acid as carbon source. To compare the electrochemical performance, LTP-2 and LTP-3 were synthesized by the same method with citric acid and lactic acid as carbon sources, respectively. After calcination, the amorphous carbon layers were coated on the surface of LiTi2(PO4)3 crystal. Carbon contents of all the samples were controlled around 9.0%. The primary particles of LTP-1 are 20–50 nm, which agglomerate into irregular micron-sized secondary particles. The primary particles of LTP-2 and LTP-3 are 60–100 nm. As anode in aqueous lithium-ion batteries (LIBs), LTP-1 presented high cyclic stability and rate performance. The initial discharge capacity of LTP-1 is 60.9 mAh·g−1 at rate of 10 C. After cycling for 1000 cycles, the capacity retention rate of LTP-1 is 72.8%. As for LTP-2 and LTP-3, the initial specific discharge capacity is 46.0 mAh·g−1 and 44.0 mAh·g−1, the corresponding capacity retention rates are 45.4% and 16.4%, respectively, with the same testing parameters.

Insights into the solvation chemistry in liquid electrolytes for lithium-based rechargeable batteries.

Lithium-based rechargeable batteries have dominated the energy storage field and attracted considerable research interest due to their excellent electrochemical performance. As indispensable and ubiquitous components, electrolytes play a pivotal role in not only transporting lithium ions, but also expanding the electrochemical stable potential window, suppressing the side reactions, and manipulating the redox mechanism, all of which are closely associated with the behavior of solvation chemistry in electrolytes. Thus, comprehensively understanding the solvation chemistry in electrolytes is of significant importance. Here we critically reviewed the development of electrolytes in various lithium-based rechargeable batteries including lithium-metal batteries (LMBs), nonaqueous lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs), lithium-oxygen batteries (LOBs), and aqueous lithium-ion batteries (ALIBs), and emphasized the effects of interactions between cations, anions, and solvents on solvation chemistry, and functions of solvation chemistry in different types of electrolytes (strong solvating electrolytes, moderate solvating electrolytes, and weak solvating electrolytes) on the electrochemical performance and redox mechanism in the abovementioned rechargeable batteries. Specifically, the significant effects of solvation chemistry on the stability of electrode-electrolyte interphases, suppression of lithium dendrites in LMBs, inhibition of the co-intercalation of solvents in LIBs, improvement of anodic stability at high cut-off voltages in LMBs, LIBs and ALIBs, regulation of redox pathways in LSBs and LOBs, and inhibition of hydrogen/oxygen evolution reactions in LOBs are thoroughly summarized. Finally, the review concludes with a prospective outlook, where practical issues of electrolytes, advanced in situ/operando techniques to illustrate the mechanism of solvation chemistry, and advanced theoretical calculation and simulation techniques such as "material knowledge informed machine learning" and "artificial intelligence (AI) + big data" driven strategies for high-performance electrolytes have been proposed.

Layered transition metal oxides (LTMO) for oxygen evolution reactions and aqueous Li-ion batteries.

This perspective paper comprehensively explores recent electrochemical studies on layered transition metal oxides (LTMO) in aqueous media and specifically encompasses two topics: catalysis of the oxygen evolution reaction (OER) and cathodes of aqueous lithium-ion batteries (LiBs). They involve conflicting requirements; OER catalysts aim to facilitate water dissociation, while for cathodes in aqueous LiBs it is essential to suppress water dissociation. The interfacial reactions taking place at the LTMO in these two distinct systems are of particular significance. We show various strategies for designing LTMO materials for each desired aim based on an in-depth understanding of electrochemical interfacial reactions. This paper sheds light on how regulating the LTMO interface can contribute to efficient water splitting and economical energy storage, all with a single material.

Toward High-Energy-Density Aqueous Lithium-Ion Batteries Using Silver Nanowires as Current Collectors

The lack of suitable lightweight current collectors is one of the primary obstacles preventing the energy density of aqueous lithium-ion batteries (ALIBs) from becoming competitive. Using silver nanowire (AgNW) films as current collectors and a molecular crowding electrolyte, we herein report the fabrication of ALIBs with relatively good energy densities. In the 2 m LiTFSI-94% PEG-6% H2O solution, the AgNW films with a sheet resistance of less than 1.0 ohm/square exhibited an electrochemical stability window as broad as 3.8 V. The LiMn2O4//Li4Ti5O12 ALIBs using AgNW films as the current collectors demonstrated an initial energy density of 70 Wh/kg weighed by the total mass of the cathode and anode, which retained 89.1% after 50 cycles.