Dual-ion Batteries Research Articles

Unraveling the Irreversible Storage of Dimethyl Carbonate-Solvated Hexafluorophosphate Anions in Graphite Electrode.

LiPF6 dissolved in dimethyl carbonate (DMC) is one of the cheapest groups of electrolyte solutions in dual-ion batteries. Generally, the discharge capacity of anion storage delivered by the graphite cathode grows with increasing LiPF6 concentration. This fact is consistent with the irreversible storage of DMC-solvated PF6-, and then, the underlying mechanism is clarified by the electrochemical tests and ex situ X-ray diffraction (XRD) measurements of graphite cathodes as well as infrared (IR) and Raman spectroscopy characterizations of solutions. Moreover, quaternary ammonium salts have facile dissociation, which can effectively regulate the solvation state of the anion and the interaction between ion pairs in the electrolyte. A small amount of tetrabutylammonium hexafluorophosphate (TBAPF6) is introduced into the highly concentrated LiPF6-DMC solution to improve the performance of the graphite cathode. The discharge capacity of the Li/graphite cell has increased by approximately 50%. This effect is also correlated with the solvation state of the anion. This study provides an insightful clue for the choice of electrolyte solution in dual-ion batteries.

Binder-induced ultrafast PF6−-intercalation toward a high-voltage, high-power and long-cycling zinc–graphite dual-ion battery

Binder-induced ultrafast PF6−-intercalation toward a high-voltage, high-power and long-cycling zinc–graphite dual-ion battery

A non-aqueous Li+/Cl− dual-ion battery with layered double hydroxide cathode

Dual-ion batteries (DIBs) have unique advantages in energy storage, such as high energy density and low cost. However, most studies on organic DIBs use anions with a large ionic radius (PF6−, TFSI−, etc.). Here, we propose a Li+/Cl− dual-ion battery (DIB) through using CoFe-Cl layered double hydroxides (LDHs) and non-aqueous LiCl electrolytes, with a mechanism involving anionic insertion into the LDHs cathode and lithium plating/stripping on the anode. Coupled X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques indicate reversible expansion/extraction of (003) crystal planes of LDHs and valence state changes of Co and Fe, enabling high Cl− storage capacities of 145 mAh/g and 137 mAh/g at 200 mA/g and 1 A/g, respectively. Furthermore, this DIB demonstrates an impressive power density of 1770 W/kg with an energy density of 240 Wh/kg. This work provides a reference for developing high performance DIBs and expands the electrochemical application field of LDHs.

2D Conjugated Metal-Organic Frameworks Bearing Large Pore Apertures and Multiple Active Sites for High-Performance Aqueous Dual-Ion Batteries.

2D conjugated metal-organic frameworks (2D c-MOFs) with large pore sizes and high surface areas are advantageous for adsorbing iodine species to enhance the electrochemical performance of aqueous dual-ion batteries (ADIBs). However, most of the reported 2D c-MOFs feature microporous structures, with few examples exhibiting mesoporous characteristics. Herein, we developed two mesoporous 2D c-MOFs, namely PA-TAPA-Cu-MOF and PA-PyTTA-Cu-MOF, using newly designed arylimide based multitopic catechol ligands (6OH-PA-TAPA and 8OH-PA-PyTTA). Notably, PA-TAPA-Cu-MOF exhibits the largest pore sizes (3.9 nm) among all reported 2D c-MOFs. Furthermore, we demonstrated that these 2D c-MOFs can serve as promising cathode host materials for polyiodides in ADIBs for the first time. The incorporation of triphenylamine moieties in PA-TAPA-Cu-MOF resulted in a higher specific capacity (423.4 mAh g-1 after 100 cycles at 1.0 A g-1) and superior cycling performance, retaining 96 % capacity over 1000 cycles at 10 A g-1 compared to PA-PyTTA-Cu-MOF. Our comparative analysis revealed that the increased number of N anchoring sites and larger pore size in PA-TAPA-Cu-MOF facilitate efficient anchoring and conversion of I3 -, as supported by spectroscopic electrochemistry and density functional theory calculations.

Electrolyte design for high power dual-ion battery with graphite cathode for low temperature applications

The design of electrolyte suitable for low-temperature use is of great significance to expand the applications of energy storage devices. Dual-ion battery (DIB) with fast ion transport kinetics is expected to be a nascent battery system that can deliver high power density both at room temperature and low temperatures. In this work, we design a 4.8 M lithium bis(fluorosulfonyl)imide in 2,2,2-trifluoroethyl acetate/dimethyl carbonate (LiFSI FEA/DMC) + 1 % LiPF6 electrolyte with a low melting point of about −93 °C, enabling graphite cathode in a DIB to achieve excellent fast charge/discharge capability with a high capacity of about 108 mAh g−1 and 80 mAh g−1 at 10 C at 25 °C and 0 °C, respectively. Even at −30 °C, the graphite cathode can still give a capacity of 69.2 mAh g−1 at 0.5 C. The graphite||Li DIB with 4.8 M LiFSI FEA/DMC + 1 % LiPF6 electrolyte also exhibits a stable cycle life with a capacity retention of 91.5 % at 5 C after 2000 cycles at 25 °C. The electrolyte forms a uniform cathode electrolyte interface film on the graphite surface, as confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy, which enables the outstanding electrochemical performance of the graphite cathode in a wide working temperature range from −30 °C to 25 °C.

Upcycling the spent graphite/LiCoO2 batteries for high-voltage graphite/LiCoPO4-co-workable dual-ion batteries

Upcycling the spent graphite/LiCoO2 batteries for high-voltage graphite/LiCoPO4-co-workable dual-ion batteries

Crucial Roles of Ethyl Methyl Carbonate in Lithium-Ion and Dual-Ion Batteries: A Review.

The essential role of electrolyte solutions in traditional electrochemical energy storage devices is crucial to enhancing their performance. Consequently, a wide array of electrolyte mixtures along with diverse electrodes have been extensively explored across different models of secondary batteries. Fascinatingly, the role of ethyl methyl carbonate (EMC) as a key cosolvent in the electrolyte mixture of commercial lithium-ion batteries with a graphite anode is garnering growing attention in alternative rechargeable dual-ion batteries utilizing graphite cathodes. In this context, the advancement and function of EMC as a solvent in electrolyte mixtures for lithium-ion and dual-ion batteries were extensively and thoroughly examined in this analysis, encompassing the genesis, synthesis process, and diverse characteristics for the practical uses of these batteries. Here, the review aims to guide readers in understanding EMC's function and impact as a cosolvent in electrolyte mixtures for both major secondary lithium-ion and dual-ion batteries, considering their distinct physicochemical characteristics.

Methyl Acetate Boosts the Low-Temperature Performance of Li4Ti5O12/Graphite Dual-Ion Batteries.

Methyl acetate (MA) is a suitable solvent for low-temperature electrolyte solutions, but its poor stability against lithium metal is a big problem. Herein, a simple and cheap solution of LiPF6 dissolved in MA was successfully employed for Li4Ti5O12/graphite dual-ion batteries (DIBs). This cell has a long cycle life with 93.1% capacity retention after 1000 cycles. Moreover, it has superior performance at low temperatures (-40 °C) compared to other reported DIBs. The storage behavior of PF6- solvated by MA in graphite cathode has been investigated in detail by in situ X-ray diffraction (XRD) in combination with electrochemical dilatometry (ECD).

An anode-free sodium dual-ion battery

Batteries with both high energy and power densities are desired for practical applications. Constructing anode-free batteries is effective to achieve high energy density, yet remains highly challenging to obtain high power density simultaneously. To overcome this dilemma, dual-ion storage strategy is introduced to anode-free battery. As a proof of concept, an anode-free sodium dual-ion battery (AFSDIB) with combined high energy and power densities is successfully fabricated. Plasma-treated current collector (Al/N-C) exhibits a sodiophilic N-doped carbon surface, enabling highly reversible Na plating/stripping at high current densities. Meanwhile, the sluggish desolvation process is intrinsically eliminated at the polytriphenylamine (PTPAn) cathodic side owing to the solvation-free anion storage chemistry. Consequently, the assembled Al/N-C||PTPAn AFSDIB exhibits a remarkable energy density over 380 Wh kg−1 (at 375 W kg−1) and power density above 1800 W kg−1 (at 302 Wh kg−1) based on active materials and consumed electrolyte, which is superior to the reported state-of-the-art anode-free and dual-ion sodium batteries. This work paves a new pathway for developing batteries with both high energy and power densities.

On-Water Surface Synthesis of Vinylene-Linked Cationic Two-Dimensional Polymer Films as the Anion-Selective Electrode Coating.

Vinylene-linked two-dimensional polymers (V-2DPs) and their layer-stacked covalent organic frameworks (V-2D COFs) featuring high in-plane π-conjugation and robust frameworks have emerged as promising candidates for energy-related applications. However, current synthetic approaches are restricted to producing V-2D COF powders that lack processability, impeding their integration into devices, particularly within membrane technologies reliant upon thin films. Herein, we report the novel on-water surface synthesis of vinylene-linked cationic 2DPs films (V-C2DP-1 and V-C2DP-2) via Knoevenagel polycondensation, which serve as the anion-selective electrode coating for highly-reversible and durable zinc-based dual-ion batteries (ZDIBs). Model reactions and theoretical modeling revealed the enhanced reactivity and reversibility of the Knoevenagel reaction on the water surface. On this basis, we demonstrated the on-water surface 2D polycondensation towards V-C2DPs films that show large lateral size, tunable thickness, and high chemical stability. Representatively, V-C2DP-1 presents as a fully crystalline and face-on oriented film with in-plane lattice parameters of a=b≈43.3 Å. Profiting from its well-defined cationic sites, oriented 1D channels, and stable frameworks, V-C2DP-1 film possesses superior bis(trifluoromethanesulfonyl)imide anion (TFSI-)-transport selectivity (transference, t_=0.85) for graphite cathode in high-voltage ZDIBs, thus triggering additional TFSI--intercalation stage and promoting its specific capacity (from ~83 to 124 mAh g-1) and cycling life (>1000 cycles, 95 % capacity retention).

Chlorination Design for Highly Stable Electrolyte toward High Mass Loading and Long Cycle Life Sodium-Based Dual-Ion Battery.

Sodium-based dual ion batteries (SDIBs) have garnered significant attention as novel energy storage devices offering the advantages of high-voltage and low-cost. Nonetheless, conventional electrolytes exhibit low resistance to oxidation and poor compatibility with electrode materials, resulting in rapid battery failure. In this study, for the first time, a chlorination design of electrolytes for SDIB, is proposed. Using ethyl methyl carbonate (EMC) as a representative, chlorine (Cl)-substituted EMC not only demonstrates increased oxidative stability ascribed to the electron-withdrawing characteristics of chlorine atom, electrolyte compatibility with both the cathode and anode is also greatly improved by forming Cl-containing interface layers. Consequently, a discharge capacity of 104.6 mAh g-1 within a voltage range of 3.0-5.0V is achieved for Na||graphite SDIB that employs a high graphite cathode mass loading of 5.0mg cm-2, along with almost no capacity decay after 900 cycles. Notably, the Na||graphite SDIB can be revived for an additional 900 cycles through the replacement of a fresh Na anode. As the mass loading of graphite cathode increased to 10mg cm-2, Na||graphite SDIB is still capable of sustaining over 700 times with ≈100% capacity retention. These results mark the best outcome among reported SDIBs. This study corroborates the effectiveness of chlorination design in developing high-voltage electrolytes and attaining enduring cycle stability of Na-based energy storage devices.

Recent advances in organic cathodes for dual-ion batteries

Recent advances in organic cathodes for dual-ion batteries

Structure engineering and heteroatom doping-enabled high-energy and fast-charging dual-ion batteries

Sodium dual-ion batteries (SDIBs) have attracted extensive attention due to the high working voltage and low cost. Nevertheless, lack of robust anode materials that can achieve highly efficient insertion/extraction of sodium ions still remains a huge challenge to develop the high-performance SDIBs. Herein, we exhibited excellent long-cycling performance (capacity retention of 85 % over 2000 cycles) with large reversible capacity (1788 mA h g−1 under 0.2 A/g) as well as superior rate capability (721 mA h g−1 under 10 A/g) for sodium-ion storage by encapsulating red phosphorus within nitrogen-doped mesoporous graphene particles. And the structural stability of composite during sodiation was directly demonstrated using in-situ transmission electron microscopy. The results of density functional theory reveal that nitrogen doping and formation of PC chemical bonds within graphene matrix may improve the adsorption energy of P atoms and promote the sturdy contact. The adsorption energies of nitrogen-doped graphene for Na+ and PF6− are −2.12 and −3.62 eV, respectively, which shows that the doping of N element is beneficial to the adsorption of Na+ and PF6−. Upon pairing with nitrogen-doped mesoporous graphene particles as cathode, an innovative SDIBs with high energy-power-density of 324 W h kg−1 at 331 W kg−1 and 187 W h kg−1 at 2665 W kg−1 were manufactured. This study opens up an effective strategy towards high-performance SDIBs for electric vehicles and other applications.

Constructing π-π Superposition Effect of Tetralithium Naphthalenetetracarboxylate with Electron Delocalization for Robust Dual-ion Batteries.

Organics are gaining significance as electrode materials due to their merits of multi-electron reaction sites, flexible rearrangeable structures and redox reversibility. However, organics encounter finite electronic conductivity and inferior durability especially in organic electrolytes. To circumvent above barriers, we propose a novel design strategy, constructing conductive network structures with extended π-π superposition effect by manipulating intermolecular interaction. Tetralithium 1,4,5,8-naphthalenetetracarboxylate (LNTC) interwoven by carbon nanotubes (CNTs) forms LNTC@CNTs composite firstly for Li-ion storage, where multiple conjugated carboxyls contribute sufficient Li-ion storage sites, the unique network feature enables electrolyte and charge mobility conveniently combining electron delocalization in π-conjugated system, and the enhanced π-π superposition effect between LNTC and CNTs endows laudable structural robustness. Accordingly, LNTC@CNTs maintain an excellent Li-ion storage capacity retention of 96.4% after 400 cycles. Electrochemical experiments and theoretical simulations elucidate the fast reaction kinetics and reversible Li-ion storage stability owing to the electron delocalization and π-π superposition effect, while conjugated carboxyls are reversibly rearranged into enolates during charging/discharging. Consequently, a dual-ion battery combining this composite anode and expanded graphite cathode exhibits a peak specific capacity of 122 mAh g-1 and long cycling life with a capacity retention of 84.2% after 900 cycles.

Integrating p-type phenazine into covalent triazine framework to achieve co-storage of cations and anions for quasi-solid-state dual-ion batteries

Covalent triazine frameworks (CTFs) with bipolar features have garnered significant attentions in energy storage systems. Further, the integration of p-type active sites into CTFs is highly desirable. Herein, we integrated p-type phenazine into CTFs (PZ-CTF) to generate dual active centers with ion co-storage mechanism. Interestingly, the application of PZ-CTF as the cathode material in various battery systems was demonstrated. In lithium-based dual-ion batteries (LDIBs) with liquid electrolyte, PZ-CTF can show high discharge specific capacity (190.8 mAh g−1 at 200 mA g−1) and excellent rate capability (92.8 mAh g−1 at 3000 mA g−1). In quasi-solid-state LDIBs, PZ-CTF can possess high discharge specific capacity (187.5 mAh g−1 at 200 mA g−1) and long-cycle stability (at 500 mA g−1 over 1000 cycles). In addition, in graphite-based DIBs (GDIBs), PZ-CTF also shows considerable electrochemical properties. Moreover, the continuous co-storage mechanism of PF6− and Li+ in PZ-CTF was confirmed by the theoretical calculations and spectral characterizations. This work opens a new avenue for integrating multi-polar organic electrode materials with multiple reaction mechanisms for the application of various battery systems.

Insights into self-discharge processes of Al-graphite batteries

Aluminum graphite dual ion batteries (AGDIB) have been widely explored thanks to abundant electrode materials, a long cycle life and high power density. However, the shelf life of AGDIBs is so far barely understood. This work's detailed self-discharge investigations allow the quantification of capacity losses for up to 4 weeks, confirm a deintercalation mechanism by Raman spectroscopy and X-ray diffraction, and furthermore give insight to influence factors. While a cell employing typical materials such as a natural graphite cathode, Mo current collector and AlCl3/[EMIm]Cl=1.5 ionic liquid electrolyte exhibits a capacity loss of 10 % in 24 h, this value can be significantly reduced to 3 % in 24 h when using a glassy carbon current collector and AlCl3/Et3NHCl=1.5 electrolyte instead. Iron impurities within the electrolyte do not affect battery capacities or self-discharge, since it is deposited on the Al anode within the battery soon after assembly. In general, the instability of the current collector material, gas evolution due to electrolyte oxidation at high cell potentials, and cationic electrolyte species greatly influence the self-discharge independently. Electrolyte speciation changes directly related to self-discharge processes are revealed by IR spectroscopy.

Unlocking Four-electron Conversion in Tellurium Cathodes for Advanced Magnesium-based Dual-ion Batteries.

Magnesium (Mg) batteries hold promise as a large-scale energy storage solution, but their progress has been hindered by the lack of high-performance cathodes. Here, we address this challenge by unlocking the reversible four-electron Te0/Te4+ conversion in elemental Te, enabling the demonstration of superior Mg//Te dual-ion batteries. Specifically, the classic magnesium aluminum chloride complex (MACC) electrolyte is tailored by introducing Mg bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2), which initiates the Te0/Te4+ conversion with two distinct charge-storage steps. Te cathode undergoes Te/TeCl4 conversion involving Cl- as charge carriers, during which a tellurium subchloride phase is presented as an intermediate. Significantly, the Te cathode achieves a high specific capacity of 543 mAh gTe -1 and an outstanding energy density of 850 Wh kgTe -1, outperforming most of the previously reported cathodes. Our electrolyte analysis indicates that the addition of Mg(TFSI)2 reduces the overall ion-molecule interaction and mitigates the strength of ion-solvent aggregation within the MACC electrolyte, which implies the facilized Cl- dissociation from the electrolyte. Besides, Mg(TFSI)2 is verified as an essential buffer to mitigate the corrosion and passivation of Mg anodes caused by the consumption of the electrolyte MgCl2 in Mg//Te dual-ion cells. These findings provide crucial insights into the development of advanced Mg-based dual-ion batteries.

Machine Learning-Driven Ionic Liquids as Electrolytes for the Advancement of High-Voltage Dual-Ion Battery

Machine Learning-Driven Ionic Liquids as Electrolytes for the Advancement of High-Voltage Dual-Ion Battery

Fluorine Chemistry in Rechargeable Batteries: Challenges, Progress, and Perspectives.

The renewable energy industry demands rechargeable batteries that can be manufactured at low cost using abundant resources while offering high energy density, good safety, wide operating temperature windows, and long lifespans. Utilizing fluorine chemistry to redesign battery configurations/components is considered a critical strategy to fulfill these requirements due to the natural abundance, robust bond strength, and extraordinary electronegativity of fluorine and the high free energy of fluoride formation, which enables the fluorinated components with cost effectiveness, nonflammability, and intrinsic stability. In particular, fluorinated materials and electrode|electrolyte interphases have been demonstrated to significantly affect reaction reversibility/kinetics, safety, and temperature tolerance of rechargeable batteries. However, the underlining principles governing material design and the mechanistic insights of interphases at the atomic level have been largely overlooked. This review covers a wide range of topics from the exploration of fluorine-containing electrodes, fluorinated electrolyte constituents, and other fluorinated battery components for metal-ion shuttle batteries to constructing fluoride-ion batteries, dual-ion batteries, and other new chemistries. In doing so, this review aims to provide a comprehensive understanding of the structure-property interactions, the features of fluorinated interphases, and cutting-edge techniques for elucidating the role of fluorine chemistry in rechargeable batteries. Further, we present current challenges and promising strategies for employing fluorine chemistry, aiming to advance the electrochemical performance, wide temperature operation, and safety attributes of rechargeable batteries.

Anion-hosting cathodes for current and late-stage dual-ion batteries

Anion-hosting cathodes for current and late-stage dual-ion batteries