Stable Solid Electrolyte Interface Research Articles

Enabling uniform Li deposition behavior by introducing a NO3−-based ionic liquid additive into carbonate electrolyte for high-voltage Li metal batteries

The nonuniform lithium deposition behavior and low deposition/dissolution reversibility are the most significant obstacles for practical high-energy-density lithium metal batteries (LMBs). Herein, a novel 1-ethyl-3-methylimidazolium nitrate ionic liquid ([EMIm][NO3] IL) is proposed to incorporate into the conventional carbonate electrolyte with a small amount of 1,2-dimethoxyethane (DME) as the cosolvent. A high solubility of 0.5 M [EMIm][NO3] in the carbonate electrolyte is achieved for high-voltage LMBs by replacing traditional lithium nitrate with [EMIm][NO3] IL, where the DME cosolvent with high donicity enables the solvation of NO3− in the electrolyte system. Benefitting from the electrochemical reduction of NO3− anions, the designed electrolyte promotes the formation of highly conductive and stable solid electrolyte interface abundant with N-containing species and achieves stable Li stripping/plating behavior. As a result, the IL-modified electrolyte enables excellent electrochemical performances with improved Coulombic efficiency (>98.5%) in Li|Cu cell and stable cyclability (900 h) in Li|Li symmetric cell, respectively. More importantly, a Li|LiNi0.8Co0.1Mn0.1O2 pouch-type battery composed of high mass loading cathode (20 mg cm−2) and thin Li foil (50 μm) maintains an impressive cycling lifespan of 100 cycles. The exploration of NO3− containing IL as a novel electrolyte additive offers a promising opportunity for achieving high-performance Li metal batteries.

Thiolate-Based Electrolytes with Anion-Dominated Solvation for Highly Stable Lithium Metal Batteries

Lithium metal has been regarded as one of the promising anodes due to its high theoretical specific capacity and low electrochemical potential. However, it is still hampered by the unstable solid electrolyte interface (SEI) and lithium dendrites. Herein, we report a class of thiolate-based salts with low dissociation but moderate ionic conductivity in ether mixture solvents for rechargeable lithium batteries, which leads to an anion-dominated solvation structure at standard concentration and is conducive to the formation of a dense LiF-rich SEI layer on the lithium metal anode surface, thereby inhibiting the continuous decomposition of the electrolyte. In addition, they are simple to prepare and have high solubility, low cost, and excellent lithium-ion transference number. Such an electrolyte is successfully applied in a Li/Li4Ti5O12 half-cell and shows promising battery performance. This work inspires a new direction to construct stable anion-derived SEI via designing the structure of lithium salts.

Flexible Freestanding Thin Polyethylene Oxide‐Based Film as Artificial Solid–Electrolyte Interface to Protect Lithium Metal in Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) that utilize sulfur and lithium (Li) metal as electrode materials are highly attractive for transportation applications due to their high theoretical gravimetric energy density. However, two major challenges currently impede the commercialization of LSB, which are the formation of Li dendrites and polysulfide shuttling. To mitigate these two effects, a protective film or artificial solid–electrolyte interface (SEI) can be applied directly to the Li‐metal surface. Herein, the preparation of freestanding polyethylene oxide (PEO)‐based films using tape casting as a scalable coating technique is presented. Moreover, the films are applied directly to the Li surface via a solvent‐free method. To demonstrate the suitability of the developed PEO‐based films, the long‐term cycling performance of the lithium–sulfur cells is discussed. It is shown that the cells with the Li‐metal surface protected by PEO‐based films achieve better stability and reproducibility, reaching ≈400 mA h g S−1 after 250 cycles compared to ≈200 mA h g S−1 after 250 cycles for the bare Li‐metal electrode. An extensive postmortem analysis of the Li‐metal electrode surface with scanning electron microscopy is additionally shown, revealing that the PEO‐based artificial SEIs form uniformly with a low level of defect layers at the interface with the Li‐metal electrode, which indicates the creation of a stable SEI.

Hexachloro-1,3-butadiene as a Functional Additive for Constructing an Efficient Solid Electrolyte Interface Layer for Long-Life Stable Li Anodes.

Lithium (Li) metal is considered as one of the attractive anodes for next-generation high-energy-density batteries due to its ultrahigh theoretical specific capacity and low potential. However, many great challenges including uncontrolled dendrite growth and undesired side reactions during repeated cycling still seriously hinder its practical application in Li metal secondary batteries. Herein, we report the hexachloro-1,3-butadiene (HCBD) molecule as a functional additive to stabilize the Li anode by forming a stable solid electrolyte interface (SEI) layer with high Li ion conductivity via in situ surface and electrochemical reactions. Density functional theory calculations demonstrate that HCBD can preferentially react with the Li anode, which generates an ionic conducting species (LiCl) into an SEI layer. The LiCl-rich SEI layer effectively regulates Li+ deposition/stripping kinetics and then induces uniform nucleation of Li+ and reduces the side reactions between the Li anode and electrolyte. With an optimal amount of HCBD in an ether-based electrolyte, an excellent cycling lifespan (7000 h) was achieved with a low hysteresis voltage of ∼10 mV at 1.0 mA cm-2 in a Li||Li symmetrical cell. Furthermore, the LiFePO4-based cell with the additive-functionalized Li anode displays obviously improved cycling stability (with a high specific capacity of 141.1 mAh g-1 after 350 cycles at 1 C).

Tuning a Solvation Structure of Lithium Ions Coordinated with Nitrate Anions through Ionic Liquid‐Based Solvent for Highly Stable Lithium Metal Batteries

AbstractRational design of promising electrolyte is considered as an effective strategy to improve the cycling stability of lithium metal batteries (LMBs). Here, an elaborately designed ionic liquid‐based electrolyte is proposed that is composed of lithium bis(trifluoromethanesulfonyl)imide as the lithium salt, 1‐ethyl‐3‐methylimidazolium nitrate ionic liquid ([EMIm][NO3] IL) and fluoroethylene carbonate (FEC) as the functional solvents, and 1,2‐dimethoxyethane (DME) as the diluent solvent. Using [EMIm][NO3] IL as the solvent component facilitates a special Li+‐coordinated NO3− solvation structure, which enables the continues electrochemical reduction of solvated NO3− and the formation of remarkably stable and conductive solid electrolyte interface. With FEC as another functional solvent and DME as the diluent solvent, the formulated electrolyte delivers high oxidative stability and ionic conductivity, and endows improved electrochemical reaction kinetics. Therefore, the formulated electrolyte demonstrates exceedingly reversible and stable Li stripping/plating behavior with high average Coulombic efficiency (98.8%) and ultralong cycling stability (3500 h). Notably, the high‐voltage Li|LiNi0.8Co0.1Mn0.1O2 full cell with IL‐based electrolyte exhibits enhanced cyclability with a capacity retention of 65% after 200 cycles under harsh conditions of low negative/positive ratio (3.1) and lean electrolyte (2.5 µL mg−1). This study creates the first NO3−‐based ionic liquid electrolyte and evokes the avenue for practical high‐voltage LMBs.

Dual structure engineering of SiOx-acrylic yarn derived carbon nanofiber based foldable Si anodes for low-cost lithium-ion batteries.

Silicon (Si) is attracted much attention due to its outstanding theoretical capacity (4200 mAh/g) as the anode of lithium-ion batteries (LIBs). However, the large volume change and low electron/ion conductivity during the charge and discharge process limit the electrochemical performance of Si-based anodes. Here we demonstrate a foldable acrylic yarn-based composite carbon nanofiber embedded by Si@SiOx particles (Si@SiOx-CACNFs) as the anode material. Since the amorphous SiOx and carbon (C) coating on the outside of the Si particles can provide a double buffer for volume expansion while reducing the contact between the Si core and the electrolyte to form a thin and stable solid electrolyte interface (SEI) film. Simultaneous in-situ electrochemical impedance spectroscopy (in-situ EIS) and galvanostatic intermittent titration technique (GITT) tests show that SiOx and C have higher ion/electron transport rates, and in addition, using acrylic fiber yarn and Zn(Ac)2 as raw materials reduces the manufacturing cost and enhanced mechanical properties. Therefore, the half-cell can achieve a high initial Coulombic efficiency (ICE) of 82.3% and a reversible capacity of 1358.2 mAh/g after 180 cycles. It can return to its original shape and remain intact after four consecutive folds, and the soft-pack full battery can also light up LED lights under different bending conditions.

Synergistic strategy of the phosphorus anode decorated by LiF and combined with KFSI-based electrolyte against shuttle effect of dissoluble polyphosphides for boosting potassium-storage performance

Phosphorus is a promising anode material for potassium-ion batteries due to the highest theoretical-specific capacity among all the proposed anode materials. So far, it is considered to have similar disadvantages to silicon anode, such as poor electronic conductivity and huge volumetric change, thus, lots of efforts have been devoted to synthesizing phosphorus/carbon hybrids. However, the electrochemical performance is still unsatisfied, due to the unclear capacity decay mechanism. Here we reveal that soluble potassium polyphosphides are generated during potassiation process and shuttle to the counter electrode where the side effects occur, leading to the loss of active phosphorus and the failure of counter electrode. To address this issue, we developed the P/CNT-LiF electrode in combination with the replacement of conventional KPF 6 by potassium bis(fluorosulfonyl)imide (KFSI) in electrolyte, in which KFSI contributes to the formation of stable and tough solid electrolyte interface (SEI), meanwhile LiF can prevent polyphosphides from diffusing to the electrolyte before and after the formation of SEI. Thus, the thin, stable and uniform SEI layer can be generated at the surface of the electrode particles, inhibiting the polyphosphides’ shuttle, contributing to the improved initial coulomb efficiency (73.7%) and reversible specific capacity (507.6 mAh g −1 after 100 cycles at 50 mA g −1 ).

“Polymer-in-ceramic” PEO/2D heterojunction composite electrolytes for solid-state batteries

The ferroelectric spontaneous polarizability of the piezoelectric TBA+CNO− also has an enhanced effect on ion transport and electrode interface modification, and its ferroelectric spontaneous polarization field also helps to reduce the generation and growth of anode dendrites. The structural instability of LRAP electrolyte Li2.99Ba0.005OCl are maintained by forming a heterojunction structure with two-dimensional nanosheets TBA+CNO−, and the fast conduction channels of lithium ions (Li+) are established. Composite electrolytes possess Li+ conductivity σi > 10−4 S/cm at 25°C. The composite materials composed of “polymer-in-ceramic” with flexibility and mechanical strength are fabricated by the casting method. PEO-Li2.99Ba0.005OCl/TBA+CNO− shows good compatibility with lithium metal, forming a stable solid electrolyte interface. The plastic crystal electrolyte dripped on the cathode side avoids the direct contact between high-voltage cathode and electrolyte and protects PEO from being oxidized and decomposed. NCM811|Li batteries show 70.9 mAh•g−1 with capacity retention of 97.88% after 100 cycles.

Highly stable lithium metal anode enabled by constructing lithiophilic 3D interphase on robust framework

Lithium (Li) metal is considered as one of the most attractive anode materials for next-generation high-energy battery systems due to its high theoretical specific capacity and low working potential. However, the low Coulombic efficiency and serious safety issues caused by uncontrollable Li dendrites and infinite volume expansion restrict commercial application. Here, a lithiophilic 3D collector is designed by introducing porous structure and lithiophilic CuO&SnO2 onto the bronze mesh to create a stable Li metal-based composite anode. The 3D porous structure with the enhanced specific surface area can effectively alleviate the volume expansion and delay the growth of Li dendrites. In addition, the lithiophilic CuO&SnO2 interphase contributes to the formation of the stable solid electrolyte interface, leading to homogeneous Li nucleation and growth. As a result, it has achieved a high average Coulombic efficiency of 98.1 % for over 600 cycles and remarkable cycling stability of 3000 h (1500 cycles) with low nucleation overpotential at 1.0 mA cm−2 with 1.0 mAh cm−2. Furthermore, the full cells assembled with LiCoO2 cathode show superior capacity retention of 90 % at 0.5C for 400 cycles. This strategy will be conducive to realizing stable anode without Li dendrites and offer opportunities for the development of high-energy batteries.

Surficial Oxidation of Phosphorus for Strengthening Interface Interaction and Enhancing Lithium-Storage Performance.

By virtue of high theoretical capacity and appropriate lithiation potential, phosphorus is considered as a prospective next-generation anode material for lithium-ion batteries. However, there are some problems hampering its practical application, such as low ionic conductivity and serious volume expansion. Herein, we demonstrated an in situ preoxidation strategy to build a oxidation function layer at phosphorus particle. The oxide layer not only acted as a protective layer to prolong the storage time of phosphorus anode in air but also carbonized N-methyl pyrrolidone and poly (vinylidene fluoride), strengthening the interfacial interaction between phosphorus particles and binder. The oxide layer further induced the formation of a stable solid electrolyte interface with high lithium-ion conductivity. The oxidized P-CNT maintained high specific capacity of 1306 mAh g-1 and 89% capacity after 100 cycles, much higher than that of pristine P-CNT (17.1%). The strategy of in situ oxidation is facile and conducive to the practical application of phosphorus-based anodes.

Plasma grown fluoride-rich artificial SEI for stabilizing Li metal anodes

The growth and detachment of lithium (Li) dendrites are regarded as the primary issues hindering the practical application of Li metal anodes, and constructing a stable solid electrolyte interface (SEI) is considered to be the most straightforward solution. Herein, carbon tetrafluoride (CF4) plasma growth instead of adding of additives into electrolyte is proposed to construct an artificial SEI. Highly reactive C- and F-containing species from the ionized CF4 react with the surface Li metal to form a stable fluoride-rich (i.e. LiF and CF) artificial SEI. Profit from the high chemical stability, low diffusion barrier and high mechanical strength of plasma-generated SEI, the distribution of lithium ions (Li+) on the surface of the prepared Li metal (F-Li) anodes is homogenized and the Li dendrites are inhibited. The symmetrical cells composed of F-Li can cycle stably for 1700 (1 mA cm−2, 1 mAh cm−2) and 1400 h (2 mA cm−2, 2 mAh cm−2) with minimum overpotentials of about 13 mV and 80 mV, respectively. The enhanced cyclability in the full cell system paired with NCM811 cathode further demonstrates its practical application. The mechanisms underlying the artificial SEI growth and its component evolution during electrochemical cycling were also discussed.

A thermoregulating separator based on black phosphorus/MOFs heterostructure for thermo-stable lithium-sulfur batteries

Apart from the traditional problems of shuttling effect of polysulfides and unmanageable growth of lithium dendrites, lithium-sulfur batteries (LSBs) could also unavoidably undergo drastic changes in internal temperature for high-rate charging/discharging process, which could shorten the cycle lifespan of the batteries. Herein, a novel asymmetric thermoregulating separator based on MOFs/black phosphorus heterostructure (UiO66@BP) was developed to address the issues above-mentioned effectively. The asymmetric separator was fabricated by encapsulating the phase-change material of paraffin wax (PW) in polyacrylonitrile nanofibers followed by vacuum filtration of UiO66@BP hybrids onto the surface of the electrospun separator. The block-adsorb-catalyze process of polysulfides in UiO66@BP heterostructure interface contributed to the smooth and effective conversion of the captive polysulfides, therefore the cell exhibited ultralow fading rate of 0.016% per cycle over 1000 cycles, which was comparable to other relative reports of Li-S cells. Moreover, the thermoregulating separator could alleviate the internal temperature rise timely since the melting process of PW could absorb large amounts of heat. The experimental results also showed that the heat absorption and preservation properties of the encapsulated PW endowed the separator with good performance in temperature adjustment, therefore the cells presented smooth and stable cycling stability as well as stable coulomb efficiency compared to none PW-based separator. This work proposed a new insight of phase-change material-based separator contributing to stable solid electrolyte interface and cycling stability of the battery in temperature-varying condition, anticipating its promising application in stable and long-life cycles Li-S batteries.

Regulating Lithium Plating/Stripping Behavior by a Composite Polymer Electrolyte Endowed with Designated Ion Channels.

The urgent demand for high energy and safety storage devices is pushing the development of lithium metal batteries. However, unstable solid electrolyte interface (SEI) formation and uncontrollable lithium dendrite growth are still huge challenges for the practical use of lithium metal batteries. Herein, a composite polymer electrolyte (CPE) endowed with designated ion channels is fabricated by constructing nanoscale Uio66-NH2 layer, which has uniformly distributed pore structure to regulate reversible Li plating/stripping in lithium metal batteries. The regular channels within the Uio66-NH2 layer work as an ion sieve to restrict larger TFSI- anions inside its channels and extract Li+ across selectively, which result in a high Li-ion transference number ( ) of 0.6. Moreover, CPE provides high ion conductivity (0.245 mS cm-1 at room temperature) and expanded oxidation window (5.1V) and forms a stable SEI layer. As a result, the assembled lithium metal batteries with CPE exhibit outstanding cyclic stability and capacity retention. The Li/CPE/Li symmetric cell continues plating/stripping over 500h without short-circuiting. The Li/CPE/LFP cell delivers a reversible capacity of 149.3 mAh g-1 with a capacity retention of 99% after 100 cycles.

A tailorable and stable lithium-oxygen battery with close to theoretical charge-discharge overpotential

Rechargeable lithium-Oxygen batteries (LOBs) are attractive alternatives to lithium ion batteries due to their high theoretical energy density. However, a large charge-discharge overpotential is usually accompanied, which reduces the energy efficiency and the cycling life. Redox mediators can be introduced in LOBs to reduce the overpotential by effectively decomposing the discharged product, lithium peroxide. Here, we propose 10-ethylphenoxazine as an active additive in the electrolyte to reduce the overpotential to 0.3 V and increase the energy efficiency to 90.4%. The 10-ethylphenoxazine is believed to favor the formation of stable solid electrolyte interface layer on the lithium anode, which benefits the even accumulation of the Li+ on the anode surface to prevent the formation of dendrite and improve the stability of Li foil against the attack of soluble species in the electrolyte. In addition, by utilizing a self-supporting graphene aerogel as the cathode, the LOB can be tailored to different sizes and shapes. The tailorable LOB features the low charging-discharging overpotential of 0.3 V and can be stably cycled for 93 times. With its excellent tailorability and stable electrochemical performance, the current LOB holds a promising future to power portable electronic devices with individualized sizes and shapes.

Enhanced Thermal Stability of Mesoporous Carbon Microbeads-Based Lithium-Ion Batteries by Propargyl Methacrylate as Electrolyte Additive.

In this current work, propargyl methacrylate (PMA) was successfully adopted to be an efficient electrolyte additive to stabilize the formation of a solid electrolyte interface (SEI) layer on mesoporous carbon microbeads (MCMB) in Li-ion batteries, especially at elevated temperatures. According to a series of material and electrochemical characterizations, the optimized concentration of PMA additive in the electrolyte was found to be 0.5 wt.%. The MCMB electrode cycled with the optimized 0.5 wt.% PMA-containing electrolyte exhibited impressive capacity retention of 90.3% after 50 cycles at 0.1C at elevated temperature, which was remarkably higher than that using the PMA-free electrolyte (83.5%). The improved electrochemical stability at elevated temperature could be ascribed to the rapid formation of stable and thin SEI layer on MCMB surface, which were investigated and suggested to be formed via PMA copolymerization reactions.

A low fraction electrolyte additive as interface stabilizer for Zn electrode in aqueous batteries

The electrochemical performance of Zn metal anode in aqueous batteries is challenged by serious parasitic reactions and dendrite growth. Herein, we introduce an interface stabilizer of 2,3,4,5-tetrahydrothiophene-1,1-dioxide (TD), with a low volume fraction of 0.5%, in the 3 m ZnSO4 electrolyte for zinc batteries. Theoretical calculations and experimental analysis confirm the adsorption of TD molecules on Zn surface, which inhibits the spontaneous chemical corrosions by mildly acidic electrolytes and ensures a homogeneous electrode surface. The adsorbed TD further induces a stable solid-electrolyte interface (SEI) composed of organic sulfone/sulfonate species and inorganic zinc salts. The parasitic reactions are further suppressed. Meanwhile, the Zn2+ flux is homogenized in SEI, and uniform Zn deposition is realized. In the ZnSO4 electrolyte with 0.5% TD additive, stable Zn plating-stripping is achieved for 2500 h at 5 mA cm−2 and 2 mAh cm−2, which is 20 times longer than in the TD free electrolyte. Moreover, the Zn//V6O13·H2O full batteries with limited anode of N/P = 4 and N/P = 1.3 realize 93.8% and 75.0% capacity retentions, respectively, after 200 cycles with the 0.5% TD electrolyte, superior to 74.3% and 43.6% with the TD free electrolyte. Our work presents an effective strategy to promote the stability of Zn electrode for high performance aqueous batteries.

Transfer Learning Enabled Deep Learning Model for the Prediction of Battery Performance from Electrolyte Formulations

Next generation batteries utilizing lithium (Li) metal anode could represent a 10x improvement in anode specific capacity compared to currently used graphite anodes however they still face major challenges associated with their evenness of plating and interfacial stability with the electrolyte. The capability to quickly evaluate and optimize liquid electrolyte formulations that can form stable solid-electrolyte interface (SEI) layers and bring out the best battery performance across a range of relevant performance outcomes will be critical to the realization of these next generation batteries. Integrating AI into battery research and development workflows has the potential to significantly increase the rate of new materials discovery, however, while machine learning models can successfully predict expected specific capacity or cycle life of the battery based on electrode designs, the complexity of liquid electrolytes used in batteries needs more contextual information than a machine or deep learning models can capture from simple structure-performance correlations. The lithium metal anode SEI layer is a formed out of the complex physio-chemical interactions between the lithium metal and the electrolyte and models will likely need to be able to capture those molecular attributes within the electrolyte composition that are decisive in electrolyte-Li interfacial chemistry. For this purpose, we will discuss the scope of two AI approaches that can predict battery performance based on electrolyte composition. The first approach showcases the capability of a deep learning model that is designed specially to represent electrolyte formulation based on structure-to-performance relationship. The second approach improves upon the first by incorporating transfer learning of quantum chemical attributes of electrolyte molecules and building a property-to-performance correlation. We will also discuss how transfer learning of ‘selective’ quantum chemical properties of electrolyte molecules to the capacity predicting deep learning model broadens the scope of the model towards recognizing new beneficial additives to the electrolyte formulation. Using this approach, the model retains impressive predictive accuracies despite limited experimental training data and predictions are validated and improved with experimental feedback for new electrolyte formulations in coin cell tests.

A Facile, Lithium Salt in Polymer Interfacial Layer for Lithium Anode Stability in Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) have garnered interest recently due to their 8-fold increase in theoretical capacity compared to state-of-the-art Li-ion batteries (LIBs), the affordability of sulfur at $100/ton, and the low environmental impact of sulfur. However, just like LIBs, LSBs suffer from anode instability due to dendrite formation and an unstable solid electrolyte interface (SEI). In this work, we address anode stability via a facile, polymer and lithium salt interfacial layer. Stable SEI formation was achieved by using a fluorinated polymer and lithium salt. A conventional Celgard separator was used for mechanical support and the polymer:salt ratio was tuned. To confirm the effectiveness of the interfacial layer for anode stability, it was used as a standalone gel polymer electrolyte in a Li-Li symmetric cell. It showed remarkable stability beyond 700 hours at an energy density of 1 mA cm-2 and capacity of 1 mAh cm-2, with a steady polarization voltage of 16mV. By comparison, a Li-Li symmetric cell with a Celgard separator began to show increasing polarization voltage after just 100 hours, with a polarization voltage that gradually increased to beyond 500mV (Figure 1). This stability was achieved by a robust SEI layer that contained LiF and Li2O, hindering the formation of the dead lithium layer. The presence of these compounds was confirmed by post-mortem X-ray photoelectron spectroscopy. Dendrite formation was also physically inhibited by the presence of the polymer matrix that had a uniform morphology and pore diameter around 1 μm. Additionally, using this interfacial layer in a lithium-sulfur coin cell provided a capacity of 866 mAh g-1 at 200 cycles, a 26% improvement over lithium-sulfur cells without the interfacial layer. Figure 1

Bifunctional separator with a light-weight coating for stable anode-free potassium metal batteries

The anode-free potassium metal battery (AF-KMBs, N : P = 0 : 1) with liquid electrolyte has been proposed through a separator composite directing strategy. A facile and feasible lithium niobate/Graphene (LiNbO3@G) composite was exploited to modify the glass fiber separator, which can realize high-performance AF-KMBs comprising a configuration of Cu||LiNbO3@G||K0.51V2O5. Due to the ferroelectric and polarization of LiNbO3, a stable solid electrolyte interface (SEI) was steadily formed at the anode interface after preliminary electrochemical activation. Combined with morphology observation and electrochemical characterization, it was proved that potassium was uniformly nucleated and selectively deposited on copper foil without obvious K dendrite. Attributed to the high conductivity of potassium ions and stable SEI, good Coulombic efficiency and long cycle life of the obtained AF-KMBs have been achieved. Consequently, our work demonstrates of great necessity to further explore the high-performance potential of anode-free potassium metal battery.

Triple‐Functional Polyoxovanadate Cluster in Regulating Cathode, Anode, and Electrolyte for Tough Aqueous Zinc‐Ion Battery

AbstractDespite a promising outlook due to the intrinsic low cost and high safety, the practical application of aqueous Zn‐ion battery is impeded by the severe mutual problems of cathode dissolution, electrolyte parasitic reactions, and metallic anode dendrite growth. Herein, a triple‐functional strategy is proposed that a polyoxovanadate (POV) cluster of K10[VIV16VV18O82] as a promising Zn2+ host can concomitantly stabilize the cluster cathode, aqueous electrolyte, and metallic Zn anode. An in situ generated cathode electrolyte interface via anodic oxidation is identified as effective in preventing the dissolution of POV cathode. Molecular dynamics simulation and density functional theory calculation confirm that the [VIV16VV18O82]10− polyoxoanions can synergistically suppress electrolyte side reactions by modulating the primary solvation shell of Zn2+‐6H2O, and random anode dendrite growth by in situ constructing a stable solid electrolyte interface of Zn‐POV. As a result, the Zn//POV battery exhibits unprecedented cycling durability over 10 000 cycles at high rates of 5 and 12 A g−1. In a systematic consideration, the findings enlighten the origin of triple‐functional polyoxometalates and will significantly propel the practical development of aqueous batteries.