Amino Acid-Induced Interface Charge Engineering Enables Highly Reversible Zn Anode

Despite the impressive merits of low-cost and high-safety electrochemical energy storage for aqueous zinc ion batteries, researchers have long struggled against the unresolved issues of dendrite growth and the side reactions of zinc metal anodes. Herein, a new strategy of zinc-electrolyte interface charge engineering induced by amino acid additives is demonstrated for highly reversible zinc plating/stripping. Through electrostatic preferential absorption of positively charged arginine molecules on the surface of the zinc metal anode, a self-adaptive zinc-electrolyte interface is established for the inhibition of water adsorption/hydrogen evolution and the guidance of uniform zinc deposition. Consequently, an ultra-long stable cycling up to 2200 h at a high current density of 5 mA cm⁻² is achieved under an areal capacity of 4 mAh cm⁻². Even cycled at an ultra-high current density of 10 mA cm⁻², 900 h-long stable cycling is still demonstrated, demonstrating the reliable self-adaptive feature of the zinc-electrolyte interface. This work provides a new perspective of interface charge engineering in realizing highly reversible bulk zinc anode that can prompt its practical application in aqueous rechargeable zinc batteries.     

Stable Li Metal Anode Enabled by Simultaneous Regulation of Electrolyte Solvation Chemistry and The Solid Electrolyte Interphase

The application of Li metal batteries is hindered by the uncontrollable growth of Li dendrites due to the lack of control over Li ion transfer and the formation of solid electrolyte interphase (SEI). Herein, polypropylene (PP) separator modified with acyclic polyaminoborane (PAB, (NH₂-BH₂)_n) and polyiminoborane (PIB, (NH═BH)_n) is developed to regulate electrolyte solvation chemistry and simultaneously facilitate the construction of robust SEI. The mediating effect of PAB and PIB promotes favorable formation of (O)₂ Li⁺ N to weaken the Li bonds between Li ion and solvent in the electrolyte, which homogenizes Li ion diffusion and reduces the desolvation barrier of Li ions. Additionally, the increase of anions content in the solvation sheath and the reaction between Li metal and PAB and PIB can induce the formation of [LiNBH]_n-enhanced SEI enriched with LiF and Li₃N that have Li ion conductivity and mechanical strength to tolerate the volume change of Li metal anode. Therefore, the symmetric cell exhibits a cycling lifetime of over 4000 h.     

In Situ Construction of High-Density Solid Electrolyte Interphase from MOFs for Advanced Zn Metal Anodes

Aqueous zinc anode has been re-evaluated due to the superiority in tackling safety and cost concerns. However, the limited lifespan originating from Zn dendritic and side reactions largely hamper commercial development. Currently, the coating prepared by simple slurry mixing is leaky and ineffectively isolate sulfate and water. Herein, inspired by the DFT calculations and the easy hydrolysis characteristic of MIL-125 (Ti), an in-situ grown high-dense TiO_2-x solid electrolyte interphase (HDSEI) with rich oxygen vacancies is successfully constructed in an aqueous electrolyte, in which the oxygen vacancies not only strengthen the hydrogen binding force thereby inhibiting the hydrogen precipitation by-reaction, but also reduce the migration energy barrier of zinc ions and enhance the mechanical properties. Profiting from the HDSEI, symmetric Zn cells survive up to remarkable 4200 h at 1 mA cm⁻², nearly 42-times than that of bare Zn anodes. In situ optical microscopy clearly reveals that the in situ grown HDSEI homogenizes the zinc deposition process, while bare zinc without HDSEI shows significant dendrites, confirming the protective nature of HDSEI. Furthermore, full Zn ion capacitors can deliver excellent electrochemical performance, providing a feasible in situ approach to construct HDSEI to implement dendrite-free metal anodes.     

Low-Cost Multi-Function Electrolyte Additive Enabling Highly Stable Interfacial Chemical Environment for Highly Reversible Aqueous Zinc Ion Batteries

The practicality of aqueous zinc ion batteries (AZIBs) for large-scale energy storage is hindered by challenges associated with zinc anodes. In this study, a low-cost and multi-function electrolyte additive, cetyltrimethyl ammonium bromide (CTAB), is presented to address these issues. CTAB adsorbs onto the zinc anode surface, regulating Zn²⁺ deposition orientation and inhibiting dendrite formation. It also modifies the solvation structure of Zn²⁺ to reduce water reactivity and minimize side reactions. Additionally, CTAB optimizes key physicochemical parameters of the electrolyte, enhancing the stability of the electrode/electrolyte interface and promoting reversibility in AZIBs. Theoretical simulations combined with operando synchrotron radiation-based in situ Fourier transform infrared spectra and in situ electrochemical impedance spectra further confirm the modified Zn²⁺ coordination environment and the adsorption effect of CTAB cations at the anode/electrolyte interface. As a result, the assembled Zn-MnO₂ battery demonstrates a remarkable specific capacity of 126.56 mAh g⁻¹ at a high current density of 4 A g⁻¹ after 1000 cycles. This work highlights the potential of CTAB as a promising solution for improving the performance and practicality of AZIBs for large-scale energy storage applications.     

Inorganic Filler Enhanced Formation of Stable Inorganic-Rich Solid Electrolyte Interphase for High Performance Lithium Metal Batteries

Lithium metal (LM) is a promising anode material for next generation lithium ion based electrochemical energy storage devices. Critical issues of unstable solid electrolyte interphases (SEIs) and dendrite growth however still impede its practical applications. Herein, a composite gel polymer electrolyte (GPE), formed through in situ polymerization of pentaerythritol tetraacrylate with fumed silica fillers, is developed to achieve high performance lithium metal batteries (LMBs). As evidenced theoretically and experimentally, the presence of SiO₂ not only accelerates Li⁺ transport but also regulates Li⁺ solvation sheath structures, thus facilitating fast kinetics and formation of stable LiF-rich interphase and achieving uniform Li depositions to suppress Li dendrite growth. The composite GPE-based Li||Cu half-cells and Li||Li symmetrical cells display high Coulombic efficiency (CE) of 90.3% after 450 cycles and maintain stability over 960 h at 3 mA cm⁻² and 3 mAh cm⁻², respectively. In addition, Li||LiFePO₄ full-cells with a LM anode of limited Li supply of 4 mAh cm⁻² achieve capacity retention of 68.5% after 700 cycles at 0.5 C (1 C = 170 mA g⁻¹). Especially, when further applied in anode-free LMBs, the carbon cloth||LiFePO₄ full-cell exhibits excellent cycling stability with an average CE of 99.94% and capacity retention of 90.3% at the 160th cycle at 0.5 C.     

Stable Non-flammable Phosphate Electrolyte for Lithium Metal Batteries via Solvation Regulation by the Additive

The application of lithium metal batteries (LMBs) is impeded by safety concerns. Employing non-flammable electrolytes can improve battery reliability while the cost and performance deterioration limit their popularization. Herein, a high-performance non-flammable electrolyte is designed, 1.5 m LiTFSI in propylene carbonate (PC)/triethyl phosphate (TEP) (4:1 by vol.) with 4-nitrophenyl trifluoroacetate (TFANP) as the additive, which can facilitate the construction of LiF-rich solid electrolyte interphase (SEI) on Li anode surface and cathode electrolyte interphase (CEI) on cathode surface through its prioritized decomposition. In TFANP-containing electrolyte, the decreased TEP coordination number in the solvation sheath relieves the adverse effect of active TEP on both the SEI and CEI for suppressing the growth of Li dendrites and reducing the continuous electrolyte consumption. Thus, the Li||LiNi_0.6Co_0.2Mn_0.2O₂ battery with such an electrolyte can deliver 132 mAh g⁻¹ after 150 cycles with high coulombic efficiency (99.5%) and superior rate performance (110 mAh g⁻¹ at 5 C, 1 C = 200 mA g⁻¹). This work provides a new additive insight on non-flammable electrolyte for reliable LMBs.     

Unraveling the Solvation Structure and Electrolyte Interface through Carbonyl Chemistry for Durable and Dendrite-Free Zn Anode

Aqueous Zn ion batteries are appealing systems owing to their safety, low cost, and environmental friendliness; however, their practical applicability is impeded by the growth of Zn dendrites and side reactions. Herein, a dual-functional electrolyte additive, namely acetylacetone (AT) is utilized for the simultaneous regulation of the solventized structure and anode–electrolyte interface (AEI) to achieve a durable, dendrite-free Zn anode. Theoretical calculations and experimental characterizations reveal that the AT molecule can be adsorbed onto Zn metal surface to reconstruct the AEI and allow for the primordial desolvation of [Zn(H₂O)₆]²⁺ at locations away from the surface of the Zn anode during deposition, which is attributed to the strong polarity of the carbonyl functional group. In addition, the two carbonyls of AT can replace two H₂O molecules in the primary solventized structure of Zn²⁺ to reduce the number of active H₂O molecules, efficiently suppressing Zn dendrite growth and detrimental reactions. As a proof of concept, a Zn//Cu cell is constructed in ZnSO₄ containing 3 vol.% AT electrolyte, delivering stable cycling over 1800 cycles while maintaining a high Coulombic efficiency of 99.74%. This study provides a practical approach for inhibiting dendrite growth and side reactions by harnessing carbonyl chemistry.     

A Salt-in-Metal Anode: Stabilizing the Solid Electrolyte Interphase to Enable Prolonged Battery Cycling

Metallic lithium (Li) is the ultimate anode candidate for high-energy-density rechargeable batteries. However, its practical application is hindered by serious problems, including uncontrolled dendritic Li growth and undesired side reactions. In this study a concept of “salt-in-metal” is proposed, and a Li/LiNO₃ composite foil is constructed such that a classic electrolyte additive, LiNO₃, is embedded successfully into the bulk structure of metallic Li by a facile mechanical kneading approach. The LiNO₃ reacts with metallic Li to generate Li⁺ conductive species (e.g., Li₃N and LiN_xO_y) over the entire electrode. These derivatives afford a stable solid electrolyte interphase (SEI) and effectively regulate the uniformity of the nucleation/growth of Li on initial plating, featuring a low nucleation energy barrier and large crystalline size without mossy morphology. Importantly, these derivatives combined with LiNO₃ can in-situ repair the damaged SEI from the large volume change during Li plating/stripping, enabling a stable electrode-electrolyte interface and suppressing side reactions between metallic Li and electrolyte. Stable cycling with a high capacity retention of 93.1% after 100 cycles is obtained for full cells consisting of high-loading LiCoO₂ cathode (≈20 mg cm⁻²) and composite metallic Li anode with 25 wt% LiNO₃ under a lean electrolyte condition (≈12 µL) at 0.5 C.     

A Dual-Functional Electrolyte Additive for High-Performance Potassium Metal Batteries

Potassium metal batteries (KMBs) coupled with layered transition metal oxides as cathode materials are a promising energy−storage technology owing to low cost and high capacity. However, uncontrollable dendritic growth in the K−metal anode and chemical reactivity of the layered transition metal oxide cathode against the electrolyte solution cause KMBs to suffer from low Coulombic efficiency, rapid capacity fading, and critical safety issues. In this study, an electrolyte engineering strategy is introduced by introducing adiponitrile (ADN) as a dual−functional electrolyte additive containing an electron−rich nitrile group (C≡N) in its molecule structure. Thus, the addition of 1 wt.% ADN can alter the chemical properties of the electrolyte solution, thereby improving the anode−electrolyte and cathode−electrolyte interfacial stabilities in KMBs. The formation of a potassiophilic compound with C≡N in the solid electrolyte interphase layer can guide the uniform electrodeposition of K and suppress the dendritic growth in the K−metal. Moreover, C≡N forms a strong coordination bond with the oxidized transition metal, leading the reversible redox reactions by mitigating the undesirable disproportionation reaction and improving the thermal stability of the layered transition metal oxide cathode. Computational calculations and experimental characterizations are used to verify the role of ADN additive in enhancing the electrochemical properties of KMBs.     

Zincophobic Electrolyte Achieves Highly Reversible Zinc-Ion Batteries

Zinc metal batteries show tremendous applications in wide-scale storages still impeded by aqueous electrolytes corrosion and interfacial water splitting reaction. Herein, a zincophobic electrolyte containing succinonitrile (SN) additive is proposed, the SN electrolyte shows a lower affinity for zinc but a stronger affinity for solid-state interphase (SEI). In the SN electrolyte, zinc hydroxide sulfate (ZHS) is more inclined to accumulate horizontally, forming a dense SEI protective layer on the surface of the Zn anode, effectively slowing down the corrosion of Zn and dendrite growth. The zincophobic SN electrolyte enables excellent performance: zinc plating/stripping Coulombic efficiency of 99.71% for an average of 400 cycles; stable cycles in a symmetric cell for 4000 h (0.9% zinc utilization) and 325 h (86.1% zinc utilization). The soft pack battery using limited zinc delivers maximum energy density of 57.0 Wh kg⁻¹ (based on mass loading of cathode materials and anode materials). Such a simple additive strategy provides a theoretical reference for zinc chemistry in a mild electrolyte environment in practical applications.     

N-Rich Solid Electrolyte Interface Constructed In Situ Via a Binder Strategy for Highly Stable Silicon Anode

Silicon (Si) is regarded as a promising anode material for high-energy-density lithium-ion batteries due to its high specific capacity (4200 mAh g⁻¹) and low potential (0.3 V vs Li⁺/Li). However, the large volume change (over 300%) of Si during the lithiation/delithiation process leads to severe pulverization, electrode structure destruction, and finally capacity fading, which slows down its step to practical application. Herein, a poly(vinylamine) (PVAm) binder containing amino ( NH₂) and amide ( NH CHO) is proposed to improve the stability of Si anodes from particle to electrode structure. The N-containing functional groups show strong interaction with the Si particles and form a uniform and thin layer on the surface, which would decompose and form an N-rich inorganic solid electrolyte interphase (SEI) layer during discharging. The high mechanical stability N-rich SEI helps relieve the pulverization of Si particles through stress dissipation, maintains electrode structural stability, and reduces the loss of active materials. Thus, the Si anode with PVAm binder exhibits high capacity of ≈2000 mAh g⁻¹ after 200 cycles, which is much higher than that of using Poly(vinylidene fluoride) (PVDF) binder (66 mAh g⁻¹) and Poly(vinyl alcohol) PVA binder (820 mAh g⁻¹). This facile and practical strategy provides a new perspective for the application of Si anodes in advanced batteries.     

Hydrofluoric Acid-Removable Additive Optimizing Electrode Electrolyte Interphases with Li+ Conductive Moieties for 4.5 V Lithium Metal Batteries

High-voltage lithium metal batteries (LMBs) are capable to achieve the increasing energy density. However, their cycling life is seriously affected by unstable electrolyte/electrode interfaces and capacity instability at high voltage. Herein, a hydrofluoric acid (HF)-removable additive is proposed to optimize electrode electrolyte interphases for addressing the above issues. N, N-dimethyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) aniline (DMPATMB) is used as the electrolyte additive to induce PF₆⁻ decomposition to form a dense and robust LiF-rich solid electrolyte interphase (SEI) for suppressing Li dendrite growth. Moreover, DMPATMB can help to form highly Li⁺ conductive Li₃N and LiBO₂, which can boost the Li⁺ transport across SEI and cathode electrolyte interphase (CEI). In addition, DMPATMB can scavenge traced HF in the electrolyte to protect both SEI and CEI from the corrosion. As expected, 4.5 V Li|| LiNi_0.6Co_0.2Mn_0.2O₂ batteries with such electrolyte deliver 145 mAh g⁻¹ after 140 cycles at 200 mA g⁻¹. This work provides a novel insight into high-voltage electrolyte additives for LMBs.     

A Facile Way to Construct Stable and Ionic Conductive Lithium Sulfide Nanoparticles Composed Solid Electrolyte Interphase on Li Metal Anode

Due to the high theoretical capacity and low reduction potential, metallic lithium is a promising anode material for the next generation of high-energy-density batteries. However, the dynamic Li plating/stripping process can easily destroy the unstable solid electrolyte interphase (SEI) and cause dendrite growth. Here, an artificial lithium sulfide nanoparticle composed SEI layer with superior stability and high ionic conductivity is designed by a spray quenching method. The artificial SEI layer on Li surface can effectively minimize the side reactions and suppress Li dendrite growth, and the metal electrode delivers stable cycling for 500 cycles in the symmetrical cell with carbonate electrolyte. Moreover, when this SEI-modified Li anode is coupled with a LiFePO₄ cathode, the full cell shows promoted cycling stability and rate capability. This work provides a broadly applicable and facile strategy to address the intrinsic issues of lithium metal anodes.     

Printable Solid Electrolyte Interphase Mimic for Antioxidative Lithium Metal Electrodes

Despite the ever‐growing demand for Li metals as next‐generation Li battery electrodes, little attention has been paid to their oxidation stability, which must be achieved for practical applications. Here, a new class of printable solid electrolyte interphase mimic (pSEI) for antioxidative Li metal electrodes is presented. The pSEI (≈1 µm) is directly fabricated on a thin Li metal electrode (25 µm) by processing solvent‐free, UV polymerization‐assisted printing, exhibiting its manufacturing simplicity and scalability. The pSEI is rationally designed to mimic a typical SEI comprising organic and inorganic components, in which ethoxylated trimethylolpropane triacrylate and diallyldimethylammonium bis(trifluoromethanesulfonyl)imide are introduced as an organic mimic (acting as a moisture‐repellent structural framework) and inorganic mimic (allowing facile Li‐ion transport/high Li⁺ transference number), respectively. Driven by the chemical/architectural uniqueness, the pSEI enables the thin Li metal electrode to show exceptional antioxidation stability and reliable full cell performance after exposure to humid environments.     

Interlamellar Lithium-Ion Conductor Reformed Interface for High Performance Lithium Metal Anode

Lithium metal anodes are promising for application in new-type secondary batteries. Unfortunately, low cycle life and safety peril induced by uncontrollable dendrites growth and weak solid electrolyte interface (SEI) have blocked their utilization. In this work, an interlamellar lithium-ion conductor of lithium-montmorillonite (Li-MMT) is applied to enhance the SEI properties, inhibit dendrites-germination, and thus significantly enhance electrochemical performance. Such a well-designed Li-MMT SEI not only possesses inherent fast lithium-ion channels, but also works as a reservoir to supply adequate lithium-ions in the interlaminations and periphery of Li-MMT nanosheets, offering fast lithium-ion transfer in interlaminations and sheet-to-sheet. Furthermore, the strong trend of lithium-ion absorption of Li-MMT is confirmed by density functional theory calculations and stable lithium deposition under Li-MMT SEI layer at 10 mA cm⁻² is verified via finite element modeling. As a result, a steady lithium deposition process without dendrites is achieved. Coulombic efficiency of the half-cell accomplishes a mean value of 99.1% over 400 cycles at 1 mA cm⁻², while Li-LiFePO₄ full cells show a stable capacity up to 120 mAh g⁻¹ and steady circulation over 400 loops at 1C. This work offers a novel strategy to design a high-performance SEI layer and suppress dendrite growth.     

Self-Regulation Seaweed-Like Lithium Metal Anode Enables Stable Cycle Life of Lithium Battery

Lithium (Li) metal anodes exhibit intriguing advantages for application in high-energy-density batteries. However, the short cycle life and security issues of these anodes induced by the dendrite growth and huge volumetric change of Li severely limit their practical application. Herein, a heuristic method to fabricate a self–supported seaweed-like Li metal anode directly to improve the cycle life of Li metal batteries, is reported. The unique seaweed-like morphology of the Li anode facilitates the dispersion of the local current density, impeding the uneven growth of Li dendrites, and remits the volume expansion of the anode, leading to excellent cycle performance. The as-prepared Li metal anode exhibits excellent plating–stripping stability over 600 cycles at high current density of 2 mA cm⁻² and delivers excellent stability even with the Li₄Ti₅O₁₂ cathode in the full cell. This study provides a facile strategy to prepare stable and dendrite-free Li anodes by controlling the morphology of Li metal. Thus, this study can further inspire new research ideas for preparing stable Li metal anodes.     

Sol Electrolyte: Pathway to Long-Term Stable Lithium Metal Anode

Lithium (Li) metal batteries are the subject of intense study due to their high energy densities. However, uncontrolled dendrite growth and the resulting pulverization of Li foil during the repeated plating/stripping process seriously diminish their cycling life. Herein, a facile approach using octaphenyl polyoxyethylene (OP-10)-based sol electrolyte is proposed to alleviate Li anode pulverization. This sol electrolyte possesses better ionic conductivity compared to gel and solid-state electrolytes and also homogenizes Li ion diffusion throughout the entire electrolyte efficiently. As a result, Li/Li symmetric cells using this sol electrolyte demonstrate long-term cycling stability for up to 1800 h, with a plating capacity of 3.0 mAh cm⁻² without deteriorating the integrity of the thin Li foil. Using a conventional liquid electrolyte, electrode pulverization and battery failure can be observed after just three cycles. More importantly, a parameter of “throwing power” is introduced in a metal Li battery system to characterize the homogenizing ability of Li deposition in different electrolyte systems, which can serve as a guide to the efficient selection of electrolytes for Li metal batteries.     

Phosphonium Bromides Regulating Solid Electrolyte Interphase Components and Optimizing Solvation Sheath Structure for Suppressing Lithium Dendrite Growth

Electrolyte additives play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long-life lithium metal batteries (LMBs), however, it is still challenging to design individual additive for adjusting the solid electrolyte interphase (SEI) components and changing lithium ion solvation sheath in the electrolyte at the same time for optimizing electrochemical performance. Herein, alkyl-triphenyl-phosphonium bromides (alkyl-TPPB) are designed as the electrolyte additive to enhance the stability of metallic Li anode under the guidance of multi-factor principle for electrolyte additive molecule design (EDMD). Both alkyl-TPP cations and Br⁻ anions produce positive influences on suppressing Li dendrite growth and stabilizing the unstable interphase between metallic Li anode/electrolyte. As expected, the optimized solvation sheath structure, and the stable SEI suppress Li dendrite growth. As a result, the Li||Li₄Ti₅O₁₂ cell reveals a long stable life over 1000 cycles with high Coulombic efficiency (99.9%). This work provides an insight on stabilizing SEI and optimizing solvation sheath structure with novel approach to develop long-term stability and safety LMBs.     

Excellent Cycling Stability of Sodium Anode Enabled by a Stable Solid Electrolyte Interphase Formed in Ether‐Based Electrolytes

Sodium‐ion batteries have been considered one of the most promising power sources beyond Li‐ion batteries. Although the Na metal anode exhibits a high theoretical capacity of 1165 mAh g^?1, its application in Na batteries is largely hindered by dendrite growth and low coulombic efficiency. Herein, it is demonstrated that an electrolyte consisting of 1 m sodium tetrafluoroborate in tetraglyme can enable excellent cycling efficiency (99.9%) of a Na metal anode for more than 1000 cycles. This high reversibility of a Na anode can be attributed to a stable solid electrolyte interphase formed on the Na surface, as revealed by cryogenic transmission electron microscopy and X‐ray photoelectron spectroscopy (XPS). These electrolytes also enable excellent cycling stability of Na||hard‐carbon cells and Na||Na_2/3Co_1/3Mn_2/3O₂ cells at high rates with very high coulombic efficiencies.     

Stabilizing Solid Electrolyte Interphases on Both Anode and Cathode for High Areal Capacity,High‐Voltage Lithium Metal Batteries with High Li Utilization and Lean Electrolyte

High‐energy‐density lithium metal batteries are considered the most promising candidates for the next‐generation energy storage systems. However, conventional electrolytes used in lithium‐ion batteries can hardly meet the demand of the lithium metal batteries due to their intrinsic instability for Li metal anodes and high‐voltage cathodes. Herein, an ester‐based electrolyte with tris(trimethylsilyl)phosphate additive that can form stable solid electrolyte interphases on the anode and cathode is reported. The additive decomposes before the ester solvent and enables the formation of P‐ and Si‐rich interphases on both electrodes that are ion conductive and robust. Thus, lithium metal batteries with a high‐specific‐energy of 373 Wh kg^?1 can exhibit a long lifespan of over 80 cycles under practical conditions, including a low negative/positive capacity ratio of 2.3, high areal capacity of 4.5 mAh cm^?2 for cathode, high‐voltage of 4.5 V, and lean electrolyte of 2.8 µL mAh^?1. A 4.5 V pouch cell is further assembled to demonstrate the practical application of the tris(trimethylsilyl)phosphate additive with an areal capacity of 10.2 and 9.4 mAh cm^?2 for the anode and cathode, respectively. This work is expected to provide an effective electrolyte optimizing strategy compatible with current lithium ion battery manufacturing systems and pave the way for the next‐generation Li metal batteries with high specific energy and energy density.