Artificial Solid Electrolyte Interface Research Articles

Constructing Carbon Nanobubbles with Boron Doping as Advanced Anode for Realizing Unprecedently Ultrafast Potassium Ion Storage

Carbonaceous material with favorable K+ intercalation feature is considered as a compelling anode for potassium‐ion batteries (PIBs). However, the inferior rate performance and cycling stability impede their large‐scale application. Here, a facile template method is utilized to synthesize boron doping carbon nanobubbles (BCNBs). The incorporation of boron into the carbon structure introduces abundant defective sites and improves conductivity, facilitating both the intercalation‐controlled and capacitive‐controlled capacities. Moreover, theoretical calculation proves that boron doping can effectively improve the conductivity and facilitate electrochemical reversibility in PIBs. Correspondingly, the designed BCNBs anode delivers a high specific capacity (464 mAh g−1 at 0.05 A g−1) with an extraordinary rate performance (85.7 mAh g−1 at 50 A g−1), and retains a considerable capacity retention (95.2% relative to the 100th charge after 2000 cycles). Besides, the strategy of pre‐forming stable artificial inorganic solid electrolyte interface effectively realizes high initial coulombic efficiency of 79.0% for BCNBs. Impressively, a dual‐carbon potassium‐ion capacitor coupling BCNBs anode displays a high energy density (177.8 Wh kg−1). This work not only shows great potential for utilizing heteroatom‐doping strategy to boost the potassium ion storage but also paves the way for designing high‐energy/power storage devices.

Review on Action Mechanism and Characterization of Natural/Artificial Solid Electrolyte Interphase of Lithium Battery: Latest Progress and Future Directions

At present, the basic structure and mechanism of solid electrolyte interface (SEI) have been studied based on different models. Although many researchers have observed the characteristics and properties of SEI through various characterization methods, it is still unable to explain its dynamic mechanism of action from the very small microscopic level. Among them, most researchers change the electrochemical performance of batteries by adding additives or material coating. Traditional research methods only state the performance of batteries from the appearance but lack detailed analysis of the electrochemical reaction of batteries during the research process. Based on the analysis of some models established by SEI, this study summarized the analysis of the research angle of SEI film through various characterization methods. The present traditional SEI and artificial SEI are introduced. Finally, the methods to improve the chemical performance of lithium battery and the challenges to solve the problems are summarized and prospected.

Pre-engineering artificial solid electrolyte interphase for hard carbon anodes for superior sodium storage performance.

A 5-nm-thick artificial solid electrolyte interface (SEI) was engineered for the hard carbon anodes of sodium-ion batteries. Benefiting from the artificial SEI, the hard carbon anode shows a significantly improved initial Coulombic efficiency of 94% and superior rate performance with a reversible capacity of 247 mA h g-1 after 800 cycles at 1C, 220 mA h g-1 after 400 cycles at 6C.

In situ artificial solid electrolyte interface engineering on an anode for prolonging the cycle life of lithium-metal batteries.

Lithium, with its high theoretical capacity and low potential, has been widely investigated as the anode in energy storage/conversion devices. However, their commercial applications always suffer from undesired dendrite growth, which forms in the charging process and may puncture the separator, leading to short cycle lives and even security problems. Herein, by an in situ displacement reaction using SnF2 at room temperature, we constructed an artificial solid electrolyte interface (ASEI) of LiF/Li-Sn outside the Li anode. This hybrid strategy can induce a synergy between the high Li+ conductivity of the Li-Sn alloy and good electrical insulation of LiF. Moreover, extreme synergy can be achieved by moderating the thickness of the LiF/Li-Sn ASEI, guiding dendrite-free lithium plating and stripping. As a result, a Li//LiFePO4 battery that is assembled from the LiF/Li-Sn ASEI-engineered Li anode can obtain 1000 cycled lives with 86.3% capacity retention under a charge/discharge rate of 5 C. This work provides an alternative way to construct dendrite-free lithium metal anodes, which significantly benefit the cycle lives of LMBs.

Constructing Acrylic-Bonded Stationary Phase as an Artificial SEI for Highly Stable Zn Metal Anodes

The development of aqueous zinc-ion batteries (AZIBs) has been severely restricted by metallic Zn anode issues, including Zn dendrites and uncontrollable side reactions. The direct interfacial modification of a Zn anode is a facile and effective strategy that has been favored by researchers. Herein, we propose an acrylic-bonded stationary layer as an artificial solid electrolyte interface (SEI) for the Zn anode to manipulate the Zn plating/stripping. The constructed modification layer is made of zinc acrylate cross-linked to form a three-dimensional (3D) porous structure, which can induce uniform deposition of zinc ions and balance the local electric field, thus achieving homogeneous nucleation and uniform Zn deposition. More importantly, this fabricated layer is chemically bonded to the zinc surface and can tolerate prolonged zinc deposition without shedding compared with conventional physical coatings. Consequently, the Zn/Zn symmetric cells, Zn/Na0.92V2O5·nH2O (NaVO) full cells, and Zn hybrid supercapacitors using this acrylic-bonded modified anode demonstrate greatly improved cycle performance.

A 3D Framework with Li3 N-Li2 S Solid Electrolyte Interphase and Fast Ion Transfer Channels for a Stabilized Lithium-Metal Anode.

The Li-metal anode has been recognized as the most promising anode for its high theoretical capacity and low reduction potential. However, the major drawbacks of Li metal, such as high reactivity and large volume expansion, can lead to dendrite growth and solid electrolyte interface (SEI) fracture. An in situ artificial inorganic SEI layer, consisting of lithium nitride and lithium sulfide, is herein reported to address the dendrite growth issues. Porous graphene oxide films are doped with sulfur and nitrogen (denoted as SNGO) to work as an effective lithium host. The SNGO film enables the in situ formation of an inorganic-rich SEI layer, which facilitates the transport of Li-ions, improves SEI mechanical strength, and avoids SEI fracture. In addition, COMSOL simulation results reveal that the microchannels fabricated by the 3D printing technique further shorten the Li-ion transfer pathways and homogenize heat and stress distribution in the batteries. As a result, the assembled anode shows low capacity fading of 0.1% per cycle at 2 C rate with the sulfur cathode. In addition, the high lithium utilization of the SNGO host enables the anode to provide a stable capacity at low negative/positive electrode ratios under 3 in LiS batteries.

Highly Reversible Zinc Anode Achieved by Surface Polyimide Coating for High‐Performance Aqueous Zinc‐Ion Batteries

Zinc‐ion batteries (ZIBs) are developing rapidly, due to the merits of rich resources, superior security, high theoretical capacity, and attractively low price of zinc anodes. Nevertheless, the growth of zinc dendrite and hydrogen evolution leads to the unstable and poor cycling life in ZIB systems, thus impeding the development of ZIBs. Herein, a facile polymer coating approach is applied to establish an artificial solid–electrolyte interface to restrain the frenzied growth of zinc dendrites and hydrogen evolution. The –CO–N–CO– group in polyimide (PI) has strong interaction with Zn2+. Therefore, PI coating significantly improves the wettability between anode and electrolyte and realizes rapid Zn2+ transfer kinetics. As a result, the PI‐Zn symmetrical battery not only reaches a stable cycling performance more than 900 h at 1 mA cm−2, but also owns a smaller overpotential than bare Zn. When integrating the PI‐Zn anode with a CaV8O20 cathode, the PI‐Zn//CaV8O20 battery maintains a capacity of 306.5 mA h g−1 after 2000 cycles, which is much higher than that (198 mA h g−1) of a Zn//CaV8O20 battery. This work provides a simple, yet effective method to improve the electrochemical performance of ZIBs.

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.

Constructing an organic artificial cathode electrolyte interphase of multi-functions on single-crystal LiNi0.8Co0.1Mn0.1O2 cathode

Nickel-rich layered oxide materials are of great significance for high energy density lithium-ion batteries due to their high theoretical capacity. However, interfacial side reaction is known to be an important cause for their electrochemical degradation. Herein, we construct an organic artificial solid electrolyte interface with 4-cyanophenylboronic acid (4-CPBA) as a precursor on a single-crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) surface. As a strong electron-absorbing group, cyano groups help to anchor the interfacial Ni2+ while the boronic acid groups contributes to remove the residual lithium and passivate the NCM811 surface. After wrapping the 11 nm thick artificial cathode electrolyte interface (CEI) precursor, the prepared NCM811 cathode exhibits an improved first coulomb efficiency of 93.5% at high temperature. A capacity retention of 82.5% after 200 cycles is obtained at 1C charge-discharge condition, significantly higher than that of 61.0% for the pristine cathode. The post analysis reveals that 4-CPBA is involved in the formation of CEI film and of many different functions on the cathode surface. The new interfacial modification strategy based on the synergistic interaction between the high nickel cathode material and functional organic molecules expands CEI technologies on nickel rich cathode materials.

Inhibition of Zinc Dendrites Realized by a β-P(VDF-TrFE) Nanofiber Layer in Aqueous Zn-Ion Batteries.

Uncontrollable Zn dendrite formations and parasitic side reactions on Zn electrodes induce poor cycling stability and safety issues, preventing the large-scale commercialization of Zn-ion batteries. Herein, to achieve uniform Zn deposition and suppress side reactions, an electrospun ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) copolymer, a P(VDF-TrFE) nanofiber layer, is introduced as an artificial solid–electrolyte interface on a Cu substrate acting as a current collector. The aligned molecular structure of β-P(VDF-TrFE) can effectively suppress localized current density on the Cu surface, lead to uniform Zn deposition, and suppress side reactions by preventing direct contact between electrodes and aqueous electrolytes. The half-cell configuration formed by the newly fabricated electrode can achieve an average coulombic efficiency of 99.2% over 300 cycles without short-circuiting at a current density of 1 mA cm−2 and areal capacity of 1 mAh cm−2. Stable cycling stability is also maintained for 200 cycles at a current density of 0.5 A g−1 in a full-cell test using MnO2 as a cathode.

Constructing an In Situ Polymer Electrolyte and a Na-Rich Artificial SEI Layer toward Practical Solid-State Na Metal Batteries.

Sodium is one of the most promising anode candidates for the beyond-lithium-ion batteries. The development of Na metal batteries with a high energy density, high safety, and low cost is desirable to meet the requirements of both portable and stationary electrical energy storage. However, several problems caused by the unstable Na metal anode and the unsafe liquid electrolyte severely hinder their practical applications. Herein, we report a facile but effective methodology to construct an in situ polymer electrolyte and Na-rich artificial solid-electrolyte interface (SEI) layer concurrently. The obtained integrated Na metal batteries display long cycling life and admirable dynamic performance with total inhibition of dendrites, excellent contact of the cathode/polymer electrolyte, and reduction of side reactions during cycling. The modified Na metal electrode with the in situ polymer electrolyte is stable and dendrite-free in repeated plating/stripping processes with a life span of above 1000 h. Moreover, this method is compatible with different cathodes that demonstrate outstanding electrochemical performance in full cells. We believe that this approach provides a practical solution to solid-state Na metal batteries.

Stabilization of Lithium Metal Interfaces by Constructing Composite Artificial Solid Electrolyte Interface with Mesoporous TiO2 and Perfluoropolymers.

The next generation of high-energy-density storage devices is expected to be rechargeable lithium metal batteries. However, unstable metal-electrolyte interfaces, dendrite growth, and volume expansion will compromise lithium metal batteries (LMB) safety and life. A simple drop-casting method is used to create a double-layer functional interface composed of inorganic mesoporous TiO2 and F-rich organics PFDMA. For high-quality lithium deposition, TiO2 can provide uniform mechanical pressure, abundant mesoporous channels, and increased ionic conductivity, while PFDMA provides enough F to form LiF in the first cycle and improves Li-electrolyte compatibility. Experimentsand simulations are combined toinvestigate the optimized mechanism of the LiF-rich solid electrolyte interface (SEI). The high binding energy of organic matter and Li demonstrates that Li+ preferentially binds with the F atom in organic matter. As a result, the tightly bound double-layer structure can inhibit lithium dendrite growth and slow electrolyte decomposition. Consequently, the symmetric Li||Li cell has a high stability performance of over 800 h. The assembled LiFePO4 ||Li cell can sustain 300 cycles at a 1 C rate and has a reversible capacity of 136.7 mAh g-1 .

Functional Polymer Materials for Advanced Lithium Metal Batteries: A Review and Perspective.

Lithium metal batteries (LMBs) are promising next-generation battery technologies with high energy densities. However, lithium dendrite growth during charge/discharge results in severe safety issues and poor cycling performance, which hinders their wide applications. The rational design and application of functional polymer materials in LMBs are of crucial importance to boost their electrochemical performances, especially the cycling stability. In this review, recent advances of advanced polymer materials are examined for boosting the stability and cycle life of LMBs as different components including artificial solid electrolyte interface (SEI) and functional interlayers between the separator and lithium metal anode. Thereafter, the research progress in the design of advanced polymer electrolytes will be analyzed for LMBs. At last, the major challenges and key perspectives will be discussed for the future development of functional polymers in LMBs.

In-Situ Electrodeposition of Nanostructured Carbon Strengthened Interface for Stabilizing Lithium Metal Anode.

The lithium metal anode (LMA) is regarded as one of the most promising candidates for high-energy Li-ion batteries. However, the naturally formed solid electrolyte interface (SEI) is unsatisfied, which would cause continuous dendrite growth and thus prevent the practical application of the LMA. Herein, a stable electrolytic carbon-based hybrid (ECH) artificial SEI is constructed on the LMA via the in-situ electrodeposition of an electrolyte sovlent at ultrahigh voltage. This nanostructured carbon strengthened SEI exhibits much improved ionic conductivity and mechanical strength, which enables uniform Li+ diffusion, stabilizes the interface between the electrolyte and lithium metal, and inhibits Li dendrite breeding and Li pulverization. With the protection of this ECH layer, the symmetrical cells show stable long-term cycling performance over 500 h with an ultrahigh plating capacity of 5 mAh cm-2 at the current density of 5 mA cm-2. A full cell assembled with a Li[Ni0.8Co0.1Mn0.1]O2 or LiFePO4 cathode exhibits a long-term cycling life and excellent capacity retention.

Regulating the Li Nucleation/Growth Behavior via Cu2O Nanowire Array and Artificial Solid Electrolyte Interphase toward Highly Stable Li Metal Anode.

Lithium (Li) metal has been considered to be the most promising anode material for next-generation rechargeable batteries. Unfortunately, the hazards induced by dendrite growth and volume fluctuation hinder its commercialized application. Here, a three-dimensional (3D) current collector composed of a vertically aligned Cu2O nanowire that is tightly coated with a polydopamine protective layer is developed to solve the encountered issues of lithium metal batteries (LMBs). The Cu2O nanowire arrays (Cu2O NWAs) provide abundant lithiophilic sites for inducing Li nucleation selectively to form a thin Li layer around the nanowires and direct subsequent Li deposition. The well-defined nanochannel works well in confining the Li growth spatially and buffering the volume change during the repeated cycling. The PDA coatings adhered onto the outline of the Cu2O NWAs serve as the artificial solid electrolyte interface to isolate the electrode and electrolyte and retain the interfacial stability. Moreover, the increased specific area of copper foam (CF) can dissipate the local current density and further suppress the growth of Li dendrites. As a result, CF@Cu2O NWAs@PDA realizes a dendrite-free morphology and the assembled symmetrical batteries can work stably for over 1000 h at 3 mA cm-2. When CF@Cu2O NWAs@PDA is coupled with a LiFePO4 cathode, the full cells exhibit improved cycle stability and rate performance.

LiF-rich and self-repairing interface induced by MgF2 engineered separator enables dendrite-free lithium metal batteries

Lithium metal batteries (LMBs) are promising for high-energy density rechargeable batteries while suffer from uncontrolled dendrites growth and unstable solid electrolyte interface (SEI) layer on the surface of lithium (Li) metal anodes. In this study, a facile and low-cost strategy is proposed to enable dendrite-free and long-life LMBs by coating MgF2 onto commercial polyethylene separator. The composite separator possesses excellent wettability and high thermal stability. When the MgF2 coating contacts Li metal anode directly, an artificial SEI layer is in-situ formed due to the spontaneously reaction of MgF2 and Li metal, which is composed of LiF and lithiophilic Mg. More importantly, a small amount of dissolved MgF2 can fill the micro-gaps between un-contact MgF2 coating and Li anode and repair the tiny cracks in the SEI generated during repeated charge–discharge process. Hence, a continuous SEI layer is formed throughout the entire surface of Li metal anode with lithiophilic, LiF-rich and self-repairing capabilities, protecting Li metal anode, reducing the nucleation overpotential, promoting smooth Li plating and inhibiting Li dendrites growth. The Li||Li symmetric cells, Cu||Li asymmetric cells and full cells with the MgF2 coated separators delivers significantly enhanced coulombic efficiency and cycle life in both ether-based and carbonate-based electrolyte. This design of artificial LiF-rich SEI with self-repairing capability by separator engineering paves a new insight for the application of alkali metal batteries.

Simultaneously in-situ fabrication of lithium fluoride and sulfide enriched artificial solid electrolyte interface facilitates high stable lithium metal anode

Lithium (Li) metal has to overcome key performance flaws before it can be used as the anode material for the next generation Li+ batteries. One of its major issues is Li dendrite growth and detachment, which causes safety issues and low Coulombic efficiency for Li metal batteries. Constructing a stable solid electrolyte interface (SEI) is considered to be the most straightforward solution to the Li anode interface defects. Here, we develop a facile stratagem of 2-(Fluorosulphonyl)difluoroacetic acid-treated Li foil to obtain a Li metal anode coated by the lithium fluoride and sulfide enriched composite layer (LiF/sulfide enriched Li). The experimental and theoretical simulations demonstrate that the ideal artificial SEI can induce uniform Li+ distribution at the interface and effectively inhibit dendrite growth. As results, the LiF/sulfide enriched Li symmetrical cells exhibit excellent cycling stability and low Li deposition overpotential, which maintain a low overpotential of ∼ 10 mV for over 1000 h at 1 mA cm−2 in an ether electrolyte of DME/DOL + LiTFSI and steadily cycles for 350 h in a carbonate electrolyte of EC/EMC + LiPF6. Furthermore, full cells assembled with NCM811 and sulfur cathode exhibit enhanced cyclability. This facile and controllable stratagem provides a more practical possibility for modifying the Li metal anode.

Artificial solid electrolyte interface layer based on sodium titanate hollow microspheres assembled by nanotubes to stabilize zinc metal electrodes

Recently, aqueous zinc-ion batteries with intrinsic safety, low cost, and environmental benignity have attracted tremendous research interest. However, zinc dendrites, harmful side reactions, and zinc metal corrosion stand in the way. Herein, we use lepidocrocite-type sodium titanate hollow microspheres assembled by nanotubes to constitute an artificial solid electrolyte interface layer on the zinc metal electrode. Thanks to the hierarchical structure with abundant open voids, negative-charged layered framework, low hydrophilicity, electrically insulting nature, and large ionic conductivity, the sodium titanate coating layer can effectively homogenize the electric field, promote the Zn2+ ion transfer, guide the Zn2+ ion flux, reduce the desolvation barrier, improve the exchange current density, and accommodate the plated zinc metal. Consequently, this coating layer can effectively suppress zinc dendrites and other unfavorable effects. With this coating layer, the Zn//Zn symmetric cell is able to provide an impressive cumulative zinc plating capacity of 1375 mAh cm−2 at a current density of 5 mA cm−2. This coating layer also contributes to significantly improved electrochemical performances of Zn//MnO2 battery and zinc-ion hybrid capacitor. This work offers new insights into the modifications of zinc metal electrodes.

3D cubic framework of fluoride perovskite SEI inducing uniform lithium deposition for air-stable and dendrite-free lithium metal anodes

High-capacity lithium metal batteries have attracted wide attention as the next-generation energy storage systems. However, lithium dendrite caused by uneven deposition is a primary obstacle that hinders practical application of lithium metal batteries. In this work, fluoride perovskite with 3D octahedron framework, is first utilized as artificial solid electrolyte interface (SEI) to induce uniform lithium deposition for air-stable and dendrite-free lithium metal anode. The stable perovskite KNiF3 protective layer separates lithium metal from air and electrolyte, not only increases the stability of Li metal electrode, but also improves the interface contact and Li ion conduction. As evidenced theoretically and experimentally, lithium ions can migrate through the space in 3D cubic framework of perovskite with a low energy barrier, achieving fast ions migration and homogeneous deposition. The symmetric cells protected by KNiF3 SEI deliver stable cycling over 3000 h at a high capacity of 4 mAh cm−2. Coupled with commercial LiFePO4 cathodes (LFP, 13.3 mg cm−2), LFP||Li-KNiF3 batteries show promoted cycling stability and rate capability, much better than the bare Li. This work uncovers the transport mechanism of Li+ within KNiF3 SEI, and provides an avenue to air-stable and dendrite-free lithium metal anodes.

Layered zirconium phosphate-based artificial solid electrolyte interface with zinc ion channels towards dendrite-free Zn metal anodes

The irrepressible demand for safe and renewable energy storage systems is spurring the rise of aqueous zinc-ion batteries (ZIBs). Nonetheless, the severe dendrites growth and side reactions on Zn metal anode hinder the application of aqueous ZIBs. Herein, a versatile zirconium phosphate (ZrP)-based artificial solid electrolyte interface (ASEI) on Zn anode ([email protected]) is constructed by spraying method to solve this dilemma. The unique layer structure and ion exchange properties of ZrP enable the formation of zinc ion channels in the interlayers of ZrP, which can redistribute the Zn2+ ion flux and promote the transport of Zn2+ ion at the interface of Zn anode. Moreover, the ZrP-based ASEI shows the merits of improved Zn2+ desolvation capability, high ionic conductivity and thus greatly facilitates the Zn deposition kinetics. The results reveal that the ZrP-based ASEI improves the Coulombic efficiency to 99.6% for 2000 cycles and enables the [email protected] symmetric cell to realize a dendrite-free plating/stripping with a low voltage hysteresis (45 mV) and a long lifespan (780 h) at 0.5 mA cm−2. Moreover, the feasibility of [email protected] is evaluated by coupling with common MnO2 and V2O5 as full batteries. Notably, the [email protected]//V2O5 cell exhibits outstanding cycling stability (a capacity retention of 72.8% after 5000 cycles).