Suppressing interfacial side reactions of zinc metal anode via isolation effect toward high-performance aqueous zinc-ion batteries

Aqueous zinc(Zn)-ion batteries(AZIBs)are one of the most promising large-scale energy storage devices because of the excellent features of zinc metal anodes,including high theoretical capacity(5,855 mAh·cm^(–3)and 820 mAh·g^(−1)),high safety,and natural abundance.Nevertheless,the large-scale applications of AZIBs are mainly limited by the severe interfacial side reactions of zinc metal anodes,which results in low plating/stripping Coulombic efficiency and poor cycling stability.To address this issue,we report an artificial Ta_(2)O_(5)protective layer on zinc foil(Ta_(2)O_(5)@Zn)for suppressing side reactions during Zn deposition/stripping.The results of density functional theory calculation and experiments indicate that Ta_(2)O_(5)@Zn anode can inhibit the side reactions between the electrolyte and zinc anode through the isolation effect.Benefiting from this advantage,the symmetric cells with Ta_(2)O_(5)@Zn anode delivered an ultralong lifespan of 3,000 h with a low overpotential at 0.25 mA·cm^(−2)for 0.05 mAh·cm^(−2).Furthermore,the full cells consisting of Ta_(2)O_(5)@Zn anode and MnO_(2)or NH_(4)V_(4)O_(10)cathode all present outstanding electrochemical performance,indicating its high reliability in practical applications.This strategy brings new opportunities for the future development of rechargeable AZIBs.

Ultrathin Zincophilic Interphase Regulated Electric Double Layer Enabling Highly Stable Aqueous Zinc‑Ion Batteries

The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions.Regulating the elec-trical double layer via the electrode/electrolyte interface layer is an effective strategy to improve the stability of Zn anodes.Herein,we report an ultrathin zincophilic ZnS layer as a model regu-lator.At a given cycling current,the cell with Zn@ZnS electrode displays a lower potential drop over the Helmholtz layer(stern layer)and a suppressed diffuse layer,indicating the regulated charge distribution and decreased electric double layer repulsion force.Boosted zinc adsorption sites are also expected as proved by the enhanced electric double-layer capacitance.Consequently,the symmetric cell with the ZnS protection layer can stably cycle for around 3,000 h at 1 mA cm^(-2) with a lower overpotential of 25 mV.When coupled with an I2/AC cathode,the cell demonstrates a high rate performance of 160 mAh g^(-1) at 0.1 A g^(-1) and long cycling stability of over 10,000 cycles at 10 A g^(-1).The Zn||MnO_(2) also sustains both high capacity and long cycling stability of 130 mAh g^(-1) after 1,200 cycles at 0.5 A g^(-1).

Interfacial parasitic reactions of zinc anodes in zinc ion batteries:Underestimated corrosion and hydrogen evolution reactions and their suppression strategies

Featured with high power density,improved safety and low-cost,rechargeable aqueous zinc-ion batteries(ZIBs) have been revived as possible candidates for sustainable energy storage systems in recent years.However,the challenges inherent in zinc(Zn) anode,namely dendrite formation and interfacial parasitic reactions,have greatly impeded their practical application.Whereas the critical issue of dendrite formation has attracted widespread concern,the parasitic reactions of Zn anodes with mildly acidic electrolytes have received very little attentions.Considering that the low Zn reversibility that stems from interfacial parasitic reactions is the major obstacle to the commercialization of ZIBs,thorough understanding of these side reactions and the development of correlative inhibition strategies are significant.Therefore,in this review,the brief fundamentals of corrosion and hydrogen evolution reactions at Zn surface is presented.In addition,recent advances and research efforts addressing detrimental side reactions are reviewed from the perspective of electrode design,electrode-electrolyte interfacial engineering and electrolyte modification.To facilitate the future researches on this aspect,perspectives and suggestions for relevant investigations are provided lastly.

Synergistic“Anchor‑Capture”Enabled by Amino and Carboxyl for Constructing Robust Interface of Zn Anode

While the rechargeable aqueous zinc-ion batteries(AZIBs)have been recognized as one of the most viable batteries for scale-up application,the instability on Zn anode–electrolyte interface bottleneck the further development dramatically.Herein,we utilize the amino acid glycine(Gly)as an electrolyte additive to stabilize the Zn anode–electrolyte interface.The unique interfacial chemistry is facilitated by the synergistic“anchor-capture”effect of polar groups in Gly molecule,manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn^(2+)in the local region.As such,this robust anode–electrolyte interface inhibits the disordered migration of Zn^(2+),and effectively suppresses both side reactions and dendrite growth.The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22%at 1 mA cm^(−2)and 0.5 mAh cm^(−2)over 500 cycles.Even at a high Zn utilization rate(depth of discharge,DODZn)of 68%,a steady cycle life up to 200 h is obtained for ultrathin Zn foils(20μm).The superior rate capability and long-term cycle stability of Zn–MnO_(2)full cells further prove the effectiveness of Gly in stabilizing Zn anode.This work sheds light on additive designing from the specific roles of polar groups for AZIBs.

Toward stable and highly reversible zinc anodes for aqueous batteries via electrolyte engineering

Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the poor reversibility resulting from dendrite formation and side reactions poses a major obstacle for its practical application. Electrolyte, which is regarded as the “blood” of batteries, has a direct impact on reaction kinetics, mass transport, and side reactions and thus plays a key role in determining the electrochemical performance of Zn electrodes. Therefore, considerable efforts have been devoted to modulating the electrolytes to improve the performance of Zn electrodes. Although significant progress has been made, achieving stable and highly reversible Zn electrodes remains a critical challenge. This review aims to provide a systematic summary and discussion on electrolyte strategies for highperformance aqueous Zn batteries. The(electro)-chemical behavior and fundamental challenges of Zn electrodes in aqueous electrolytes are first discussed. Electrolyte modulation strategies developed to address these issues are then classified and elaborated according to the underlying mechanisms.Finally, remaining challenges and promising future research directions on aqueous electrolyte engineering are highlighted. This review offers insights into the design of highly efficient electrolytes for new generation of rechargeable Zn batteries.

Interfacial Engineering Strategy for High-Performance Zn Metal Anodes

Due to their high safety and low cost,rechargeable aqueous Zn-ion batteries(RAZIBs)have been receiving increased attention and are expected to be the next generation of energy storage systems.However,metal Zn anodes exhibit a limited-service life and inferior reversibility owing to the issues of Zn dendrites and side reactions,which severely hinder the further development of RAZIBs.Researchers have attempted to design high-performance Zn anodes by interfacial engineering,including surface modification and the addition of electrolyte additives,to stabilize Zn anodes.The purpose is to achieve uniform Zn nucleation and flat Zn deposition by regulating the deposition behavior of Zn ions,which effectively improves the cycling stability of the Zn anode.This review comprehensively summarizes the reaction mechanisms of interfacial modification for inhibiting the growth of Zn dendrites and the occurrence of side reactions.In addition,the research progress of interfacial engineering strategies for RAZIBs is summarized and classified.Finally,prospects and suggestions are provided for the design of highly reversible Zn anodes.

Low-temperature replacement construction of three-dimensional corrosion-resistant interface for deeply rechargeable Zn metal batteries

Aqueous Zn batteries are promising candidates for grid-scale renewable energy storage.Foil electrodes have been widely investigated and applied as anode materials for aqueous Zn batteries,however,they suffer from limited surface area and severe interfacial issues including metallic dendrites and corrosion side reactions,limiting the depth of discharge(DOD)of the foil electrode materials.Herein,a low-temperature replacement reaction is utilized to in-situ construct a three-dimensional(3D)corrosion-resistant interface for deeply rechargeable Zn foil electrodes.Specifically,the deliberate low-temperature environment controlled the replacement rate between polycrystalline Zn metal and oxalic acid,producing a Zn foil electrode with distinct 3D corrosion-resistant interface(3DCI-Zn),which differed from conventional two-dimensional(2D)protective structure and showed an order of magnitude higher surface area.Consequently,the 3DCI-Zn electrode exhibited dendrite-free and anticorrosion properties,and achieved stable plating/stripping performance for 1000 h at 10 mA cm^(-2)and 10 mAh cm^(-2)with a remarkable DOD of 79%.After pairing with a MnO2cathode with a high areal capacity of 4.2 mAh cm^(-2),the pouch cells delivered 168 Wh L^(-1)and a capacity retention of 89.7%after 100 cycles with a low negative/positive(N/P)ratio of 3:1.

超稳定铁磁界面助力锌金属电池实用化

可充电的水系锌金属电池由于其低成本和高安全的特性,已成为大规模储能电池最有潜力的备选之一.然而,锌枝晶的不可控生长以及副反应多的问题(尤其在高容量充放条件下)严重阻碍了其实用化进程.本文提出了铁磁界面和磁场相结合的改性策略,有效地解决了这些问题.引入的高稳定铁磁界面层,不仅能够保证磁场在电极表面长效地调节锌均匀沉积,而且可有效地抑制表面副反应的发生.这些优势使得锌金属负极能够在82%的深度放电条件下稳定循环350 h;匹配五氧化二钒正极材料后,全电池在13.1 mg/cm^(2)的高载量条件下展现出超稳定的循环.该研究对于促进可充电锌金属电池实用化具有重要指导意义.

1D/2D composite subnanometer channels for ion transport:The role of confined water

As a mass transport media,water is an alternative of organic solvent applied in rechargeable batteries,due to its unique properties,including fast ionic migration,easy-processibility,economic/environmental friendliness,and flame retardancy.However,due to the high activity of water molecules in aqueous electrolytes,the corrosion of metal anode,side reactions,and inferior metal electrodeposition behavior leads to unstable cycling performance,poor Coulombic efficiency(CE),and early-staged failure of batteries.Despite several attempts to regulate the activity of water,migration of ions is sacrificed,due to the limited methods to control the water states.Herein,we developed a subnanoscale confinement strategy based on a nacre-like structure to modulate the activity of water in the solid electrolytes.By tuning the ratio between the two-dimensional(2D)vermiculite and one-dimensional(1D)cellulose nanofibers(CNFs),the capillary size in the 1D/2D structure is altered to achieve a fast Zn^(2+)transport.Our dielectric relaxation and molecular dynamics studies indicate that the enhanced Zn^(2+)conductivity is attributed to the fast water relaxation in the precisely defined 1D/2D capillary.Taking advantage of the regulated activity of the confined water in 2D capillary,the composite vermiculite membrane can suppress the corrosion and side reactions between Zn electrode and water molecular,endowing a reversible Zn^(2+)stripping/plating behavior and a stable cycling performance for 900 h.Based on our confinement strategy to control the water states by 1D/2D structures,this work will open an avenue toward aqueous energy storage devices with excellent reversibility,high safety,and long-term stability.

Overcoming side reaction effects in the colloidal synthesis of ZnSe/ZnS core/shell quantum dots with an etching strategy

The potential use of large-size ZnSe quantum dots as blue emitters for display applications has greatly inspired the colloidal synthesis.Herein,we report the negative effects of side reactions of large-size ZnSe quantum dots.The side reactions between oleic acid and oleylamine generated amidation products and H_(2)O,which led to the hydrolysis of Zn(OA)2 to Zn(OH)2 and the subsequent formation of zinc oxide(ZnO)and zinc bis[diphenylphosphinate](Zn(DPPA)2)precipitates.These side reactions resulted in the formation of a defective surface including a Se-rich surface and oxygen-related defects.Such negative effects can be overcome by adopting an etching strategy using potassium fluoride and myristic acid in combination.By overcoating a ZnS shell,blue emissive ZnSe/ZnS quantum dots with a maximum photoluminescence quantum yield of up to 91%were obtained.We further fabricated ZnSe quantum dots-based blue light-emitting diodes with an emission peak at 456 nm.The device showed a turn-on voltage of 2.7 V with a maximum external quantum efficiency of 4.2%and a maximum luminance of 1223 cd·m^(−2).

Enhancing electrochemical capacity and interfacial stability of lithium-ion batteries through side reaction modulation with ultrathin carbon nanotube film and optimized lithium cobalt oxide particle size

Lithium cobalt oxide(LCO),the first commercialized cathode active material for lithium-ion batteries,is known for high voltage and capacity.However,its application has been limited by relatively low capacity and stability at high C-rates.Reducing particle size is considered one of the most straightforward and effective strategies to enhance ion transfer,thus increasing the rate performance.However,side reactions are simultaneously enhanced as the specific surface area increases.Herein,we investigate the impact of LCO particles with varying size distributions and optimize the particle size.To modulate the side reactions associated with particle size reduction,an ultrathin carbon nanotube film(UCNF)is introduced to coat the cathode surface.With this simple process and optimized particle size,the rate performance improves significantly,normal commercial LCO achieves 118 mA·h·g^(−1)at 3.0–4.3 V and 20 C(0.72 mA·h·cm^(−2)),corresponding to power density of 8732 W·kg^(−1).This method is applied to high voltage as well,152 mA·h·g^(−1)at 3.0–4.6 V and 20 C(0.99 mA·h·cm^(−2))was achieved with high-voltage LCO(HVLCO),corresponding to power density of 11,552 W·kg^(−1).The cycling stability is also enhanced,with the capacity retention maintaining more than 96%after 100 cycles at 0.1 C.For the first time,UCNF is demonstrated to suppress the excessive decomposition of the electrolytes and solvents by blocking electron injection/extraction between LCO and electrolyte solution.Our findings provide a simple method for improving LCO rate performance,especially at high C-rates.

Interface engineering of Zn meal anodes using electrochemically inert Al_(2)O_(3)protective nanocoatings

Aqueous rechargeable Zn-ion batteries are regarded as a promising alternative to lithium-ion batteries owing to their high energy density,low cost,and high safety.However,their commercialization is severely restricted by the Zn dendrite formation and side reactions.Herein,we propose that these issues can be minimized by modifying the interfacial properties through introducing electrochemically inert Al_(2)O_(3)nanocoatings on Zn meal anodes(Al_(2)O_(3)@Zn).The Al_(2)O_(3)nanocoatings can effectively suppress both the dendrite growth and side reactions.As a result,the Al_(2)O_(3)@Zn symmetric cells show excellent electrochemical performance with a long lifespan of more than 4,000 h at 1 mA·cm^(−2)and 1 mAh·cm^(−2).Meanwhile,the assembled Al_(2)O_(3)@Zn//V_(2)O_(5)full cells can deliver a high capacity(236.2 mAh·g^(−1))and long lifespan with a capacity retention of 76.11%after 1,000 cycles at 4 A·g^(−1).

An organosulfide-based energetic liquid as the catholyte in highenergy density lithium metal batteries for large-scale grid energy storage

Development of catholytes with long-cycle lifespan,high interfacial stability,and fast electrochemical kinetics is crucial for the comprehensive deployment of high-energy density lithium metal batteries(LMBs)with cost-efficiency.In this study,a lithiated 2-mercaptopyridine(2-MP-Li)organosulfide was synthesized and used as the soluble catholyte for the first time.Under the routine working mode,the LMB using this 2-MP-Li catholyte possessed high capacity retention of 55.4%with a Coulombic efficiency(CE)of near 100%after 2,000 cycles.When a cell system was fully filled with 2-MP-Li catholyte,it yielded a double capacity with 15%improvement in the capacity retention,corresponding to 0.0182%capacity decay per cycle,as well as excellent rate performance even at 6 mA·cm^(−2).These superior achievements resulted from the enhanced interfacial stability of Li anode induced by the salt-type 2-MP-Li molecule and the avoiding of using neutral catholyte as the initial active material,thereby mitigating the side reactions originating from the polysulfide shuttle effect.Furthermore,density functional theory(DFT)calculation and kinetics investigations proved the pseudocapacitive characteristic and faster ion diffusion coefficient with this design.Besides,the fabricated energy storage device showed excellent performance but with low economic cost and easy processing.Such a LMB with an alterable amount of capacity has a high potential to be applied in flow-cell type batteries for large-scale grid energy storage in the future.

Tailoring the LiNbO_(3)coating of Ni-rich cathode materials for stable and high-performance all-solid-state batteries

The research and development of advanced nanocoatings for high-capacity cathode materials is currently a hot topic in the field of solid-state batteries(SSBs).Protective surface coatings prevent direct contact between the cathode material and solid electrolyte,thereby inhibiting detrimental interfacial decomposition reactions.This is particularly important when using lithium thiophosphate superionic solid electrolytes,as these materials exhibit a narrow electrochemical stability window,and therefore,are prone to degradation during battery operation.Herein we show that the cycling performance of LiNbO_(3)-coated Ni-rich LiNi_(x)Co_(y)Mn_(z)O_(2)cathode materials is strongly dependent on the sample history and(coating)synthesis conditions.We demonstrate that post-treatment in a pure oxygen atmosphere at 350℃results in the formation of a surface layer with a unique microstructure,consisting of LiNbO_(3)nanoparticles distributed in a carbonate matrix.If tested at 45℃and C/5 rate in pellet-stack SSB full cells with Li_(4)Ti_(5)O_(12)and Li_(6)PS_(5)Cl as anode material and solid electrolyte,respectively,around 80%of the initial specific discharge capacity is retained after 200 cycles(~160 mAh·g^(−1),~1.7 mAh·cm^(−2)).Our results highlight the importance of tailoring the coating chemistry to the electrode material(s)for practical SSB applications.

Meticulous guard: The role of Al/F doping in improving the electrochemical performance of high-voltage spinel cathode

Spinel LiNi0.5Mn1.5O4,which is considered as one of the most attractive candidates for high energy density battery due to its high voltage platform over 4.7 V,suffers from the side reactions with electrolyte,strong oxidability of Ni4þand therefore the complicated and frangible Solid Electrolyte Interfaces(SEI)layer that hinders the practical application of LiNi0.5Mn1.5O4.In this work,traditional coprecipitation method is applied and improved by anion and cation doping method to construct superior interface on the surface of LiNi0.5Mn1.5O4 to suppress side reactions especially at high temperature.Detailed properties including structure,morphology and electrochemical performance of pristine sample,single-doped and co-doped samples are probed.Physical characterizations reveal that the co-doped sample with regular octahedron has a moderate grain size and specific surface area between Al and F single doping,and holds the advantages of rate performance and capacity retention causing by Al doping and better stability under high temperature constructing by F.It exhibits the best capacity retention of 92%after 200 cycles under 55 C,which is higher than that of the pristine sample(87%).Analysis of the electrode after cycling shows that doping reduces the thickness of the electrode interface film and the content of inorganic substances such as LiF to improve the interface characteristics and the high temperature cycling performance.This work has certain significance for the commercial application of LiNi0.5Mn1.5O4.