Liquid metal in prohibiting polysulfides shuttling in metal sulfides anode for sodium-ion batteries

Metal sulfides are a class of promising anode materials for sodium-ion batteries(SIBs)owing to their high theoretical specific capacity.Nevertheless,the reactant products(polysulfides)could dissolve into electrolyte,shuttle across separator,and react with sodium anode,leading to severe capacity loss and safety concerns.Herein,for the first time,gallium(Ga)-based liquid metal(LM)alloy is incorporated with MoS_(2)nanosheets to work as an anode in SIBs.The electron-rich,ultrahigh electrical conductivity,and self-healing properties of LM endow the heterostructured MoS_(2)-LM with highly improved conductivity and electrode integrity.Moreover,LM is demonstrated to have excellent capability for the adsorption of polysulfides(e.g.,Na_(2)S,Na_(2)S_(6),and S_(8))and subsequent catalytic conversion of Na_(2)S.Consequently,the MoS_(2)-LM electrode exhibits superior ion diffusion kinetics and long cycling performance in SIBs and even in lithium/potassium-ion battery(LIB/PIB)systems,far better than those electrodes with conventional binders(polyvinylidene difluoride(PVDF)and sodium carboxymethyl cellulose(CMC)).This work provides a unique material design concept based on Ga-based liquid metal alloy for metal sulfide anodes in rechargeable battery systems and beyond.

Carboxylic bacterial cellulose fiber-based hydrogel electrolyte with imidazole-type ionic liquid for dendrite-free zinc metal batteries

Aqueous zinc metal batteries are regarded as the most promising energy storage system due to their advantages of high safety,low cost,and high theoretical capacity.However,the growth of dendrites and the occurrence of side reactions hinder the development of zinc metal batteries.Despite previous attempts to design advanced hydrogel electrolytes,achieving high mechanical performance and ionic conductivity of hydrogel electrolytes has remained challenging.In this work,a hydrogel electrolyte with an ionic crosslinked network is prepared by carboxylic bacterial cellulose fiber and imidazole-type ionic liquid,following by a covalent network of polyacrylamide.The hydrogel electrolyte possesses a superior ionic conductivity of 43.76 mS cm^(−1),leading to a Zn^(2+)migration number of 0.45,and high mechanical performance with an elastic modulus of 3.48 GPa and an elongation at breaking of 38.36%.More importantly,under the anion-coordination effect of the carboxyl group in bacterial cellulose and[BF4]−in imidazole-type ionic liquid,the solvation sheath of hydrated Zn^(2+)ions and the nucleation overpotential of Zn plating are regulated.The results of cycled testing show that the growth of zinc dendrites is effectively inhibited and the generation of irreversible by-products is reduced.With the carboxylic bacterial cellulose-based hydrogel electrolyte,the Zn||Zn symmetric batteries offer good cyclability as well as Zn||Ti batteries.

Designing Advanced Liquid Electrolytes for Alkali Metal Batteries:Principles,Progress,and Perspectives

The ever-growing pursuit of high energy density batteries has triggered extensive efforts toward developing alkali metal(Li,Na,and K)battery(AMB)technologies owing to high theoretical capacities and low redox potentials of metallic anodes.Typically,for new battery systems,the electrolyte design is critical for realizing the battery electrochemistry of AMBs.Conventional electrolytes in alkali ion batteries are generally unsuitable for sustaining the stability owing to the hyper-reactivity and dendritic growth of alkali metals.In this review,we begin with the fundamentals of AMB electrolytes.Recent advancements in concentrated and fluorinated electrolytes,as well as functional electrolyte additives for boosting the stability of Li metal batteries,are summarized and discussed with a special focus on structure-composition-performance relationships.We then delve into the electrolyte formulations for Na-and K metal batteries,including those in which Na/K do not adhere to the Li-inherited paradigms.Finally,the challenges and the future research needs in advanced electrolytes for AMB are highlighted.This comprehensive review sheds light on the principles for the rational design of promising electrolytes and offers new inspirations for developing stable AMBs with high performance.

Single-Phase Ternary Compounds with a Disordered Lattice and Liquid Metal Phase for High-Performance Li-Ion Battery Anodes

Si is considered as the promising anode materials for lithium-ion batteries(LIBs)owing to their high capacities of 4200 mAh g-1and natural abundancy.However,severe electrode pulverization and poor electronic and Li-ionic conductivities hinder their practical applications.To resolve the afore-mentioned problems,we first demonstrate a cation-mixed disordered lattice and unique Li storage mechanism of single-phase ternary GaSiP_(2)compound,where the liquid metallic Ga and highly reactive P are incorporated into Si through a ball milling method.As confirmed by experimental and theoretical analyses,the introduced Ga and P enables to achieve the stronger resistance against volume variation and metallic conductivity,respectively,while the cation-mixed lattice provides the faster Li-ionic diffusion capability than those of the parent GaP and Si phases.The resulting GaSiP_(2)electrodes delivered the high specific capacity of 1615 mAh g-1and high initial Coulombic efficiency of 91%,while the graphite-modified GaSiP_(2)(GaSiP_(2)@C)achieved 83%of capacity retention after 900 cycles and high-rate capacity of 800 at 10,000 mA g-1.Furthermore,the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)//Ga SiP_(2)@C full cells achieved the high specific capacity of 1049 mAh g-1after 100 cycles,paving a way for the rational design of high-performance LIB anode materials.

Ionic liquids for high performance lithium metal batteries

The pursuit of high energy density has promoted the development of high-performance lithium metal batteries.However,it faces a serious security problem.Ionic liquids have attracted great attention due to their high ionic conductivity,non-flammability,and the properties of promoting the formation of stable SEI films.Deeply understanding the problems existing in lithium metal batteries and the role of ionic liquids in them is of great significance for improving the performance of lithium metal batteries.This article reviews the effects of the molecular structure of ionic liquids on ionic conductivity,Li^(+)ion transference number,electrochemical stability window,and lithium metal anode/electrolyte interface,as well as the application of ionic liquids in Li-high voltage cathode batteries,Li-O_(2) batteries and Li-S batteries.The molecular design,composition and polymerization will be the main strategies for the future development of ionic liquid-based electrolytes for high performance lithium metal battery.

Bifunctional Liquid Metals Allow Electrical Insulating Phase Change Materials to Dual-Mode Thermal Manage the Li-Ion Batteries

Phase change materials(PCMs)are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries(LIBs)according to real-time thermal conditions,guaranteeing the reliable operation of LIBs in both cold and hot environments.Herein,we report a liquid metal(LM)modified polyethylene glycol/LM/boron nitride PCM,capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction.Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB’s structure and heat-conduction characteristic.Typically,soft and deformable LMs are modified on the boron nitride surface,serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m^(−1) K^(−1) in the vertical and in-plane directions,respectively.In addition,LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system.As a proof-of-concept,this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10℃ at high charging/discharging rate,opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway.

A stable anthraquinone-derivative cathode to develop sodium metal batteries: The role of ammoniates as electrolytes

Rechargeable sodium metal batteries constitute a cost-effective option for energy storage although sodium shows some drawbacks in terms of reactivity with organic solvents and dendritic growth.Here we demonstrate that an organic dye,indanthrone blue,behaves as an efficient cathode material for the development of secondary sodium metal batteries when combined with novel inorganic electrolytes.These electrolytes are ammonia solvates,known as liquid ammoniates,which can be formulated as NaI·3.3NH_(3) and NaBF_(4)·2.5NH_(3).They impart excellent stability to sodium metal,and they favor sodium non-dendritic growth linked to their exceedingly high sodium ion concentration.This advantage is complemented by a high specific conductivity.The battery described here can last hundreds of cycles at 10 C while keeping a Coulombic efficiency of 99%from the first cycle.Because of the high capacity of the cathode and the superior physicochemical properties of the electrolytes,the battery can reach a specific energy value as high as 210 W h kgIB^(-1),and a high specific power of 2.2 kW kgIB^(-1),even at below room temperature(4℃).Importantly,the battery is based on abundant and cost-effective materials,bearing promise for its application in large-scale energy storage.

A self-healing liquid metal anode for lithium-ion batteries

The gallium-based liquid metal as one of the self-healing materials has gained wide attention, especially in the energy storage system. However, volume expansion with the ‘‘liquid-solid-liquid”transformation process still leads to un-controlled electrode failure, which stimulates the irreversibility of liquid metal and hinders their self-healing effect as the anode for lithium-ion batteries. Herein, the polypyrrole(PPy) with highly conductive and adhesive features is first introduced to fasten the liquid metal nanoparticles(gallium-tin alloy, EGaSn) in the integrated electrode and applied as the anode for lithium-ion batteries. A tightly PPy wrapped EGaSn nanoparticles structure is formed during the in-situ polymerization synthesis process, which effectively avoids the detachment of solid alloyed products. Based on the features of PPy, polyacrylic acid is added to facilitate strengthening the integrity of the electrode by constructing the hydrogen bond. The ‘‘dual-insurance” design endows the EGaSn to exhibit superior electrochemical kinetics and an astonishing self-healing effect. As a result, the customized anode displays superior cycling stability(499.8 mAh g^(-1) after 500 cycles at 1.0 A g^(-1))and rate capability(350 mAh g^(-1) at 2.0 A g^(-1)).This work enriches the electrode engineering technology of liquid metal nanoparticles and opens up a new way to customize the self-healing anode for lithium-ion batteries.

Sb-Cu alloy cathode with a novel lithiation mechanism of ternary intermetallic formation: Enabling high energy density and superior rate capability of liquid metal battery

Antimony(Sb) is an attractive cathode for liquid metal batteries(LMBs) because of its high theoretical voltage and low cost.The main obstacles associated with the Sb-based cathodes are unsatisfactory energy density and poor rate-capability.Herein,we propose a novel Sb_(64)Cu_(36)cathode that effectively tackles these issues.The Sb_(64)Cu_(36)(melting point:525℃) cathode presents a novel lithiation mechanism involving sequentially the generation of Li_(2)CuSb,the formation of Li_(3)Sb,and the conversion reaction of Li_(2)CuSb to Li_(3)Sb and Cu.The generated intermetallic compounds show a unique microstructure of the upper floated Li_(2)CuSb layer and the below cross-linked structure with interpenetrated Li_(2)CuSb and Li_(3)Sb phases.Compared with Li_(3)Sb,the lower Li migration energy barrier(0.188 eV) of Li_(2)CuSb significantly facilitates the lithium diffusion across the intermediate compounds and accelerates the reaction kinetics.Consequently,the Li‖Sb_(64)Cu_(36)cell delivers a more excellent electrochemical performance(energy density:353 W h kg^(-1)at 0.4 A cm^(-2);rate capability:0.59 V at 2.0 A cm^(-2)),and a much lower energy storage cost of only 38.45 $ kW h^(-1)than other previously reported Sb-based LMBs.This work provides a novel cathode design concept for the development of high-performance LMBs in applications for large-scale energy storage.

Arbitrary skin metallization by pencil-writing inspired solid-ink rubbing for advanced energy storage and harvesting

The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.

Recent progress in ionic liquid-based electrolytes for nonaqueous and aqueous metal batteries

Nonaqueous Li metal batteries(LMBs)and aqueous Zn metal batteries(ZMBs)are promising next-generation secondary batteries owing to their high energy density.Selecting an appropriate electrolyte is critical for addressing the safety issues nonaqueous and aqueous metal batteries can encounter.Ionic liquids(ILs)have been widely used in secondary metal batteries because they are non-flammable,present good thermal stability,and have wide electrochemical windows.This review highlights the research progress on IL-based electrolytes for stable Li/Zn metal anodes.We focus particularly on these electrolytes'electrochemistry and functionalities at the electrolyte/anode interface for inhibiting dendrite growth,preventing side reactions,and enhancing electrochemical performance.It is expected that this review will shed some light on the development of ILs for nextgeneration metal batteries.

Self-healing Ga-based liquid metal/alloy anodes for rechargeable batteries

With the rapid development of electronics,electric vehicles,and grid energy storage stations,higher requirements have been put forward for advanced secondary batteries.Liquid metal/alloy electrodes have been considered as a promising development direction to achieve excellent electrochemical performance in metal-ion batteries,due to their specific advantages including the excellent electrode kinetics and self-healing ability against microstructural electrode damage.For conventional liquid batteries,high temperatures are needed to keep electrode liquid and ensure the high conductivity of molten salt electrolytes,which also brings the corrosion and safety issues.Ga-based metal/alloys,which can be operated at or near room temperature,are potential candidates to circumvent the above problems.In this review,the properties and advantages of Ga-based metal/alloys are summarized.Then,Ga-based liquid metal/alloys as anodes in various metal-ion batteries are reviewed in terms of their self-healing ability,battery configurations,working mechanisms,and so on.Furthermore,some views on the future development of Ga-based electrodes in batteries are provided.

Stable sodium metal anode enabled by interfacial room-temperature liquid metal engineering for high-performance sodium–sulfur batteries with carbonate-based electrolyte

Sodium(Na)metal is a competitive anode for next-generation energy storage applications in view of its low cost and high-energy density.However,the uncontrolled side reactions,unstable solid electrolyte interphase(SEI)and dendrite growth at the electrode/electrolyte interfaces impede the practical application of Na metal as anode.Herein,a heterogeneous Na-based alloys interfacial protective layer is constructed in situ on the surface of Na foil by self-diffusion of liquid metal at room temperature,named“HAIP Na.”The interfacial Na-based alloys layer with good electrolyte wettability and strong sodiophilicity,and assisted in the construction of NaF-rich SEI.By means of direct visualization and theoretical simulation,we verify that the interfacial Na-based alloys layer enabling uniform Na^(+)flux deposition and suppressing the dendrite growth.As a result,in the carbonate-based electrolyte,the HAIP Na||HAIP Na symmetric cells exhibit a remarkably enhanced cycling life for more than 650 h with a capacity of 1mAh cm^(−2)at a current density of 1mAcm^(−2).When the HAIP Na anode is paired with sulfurized polyacrylonitrile(SPAN)cathode,the SPAN||HAIP Na full cells demonstrate excellent rate performance and cycling stability.

Recent progress in rechargeable alkali metal-air batteries

Rechargeable alkali metal-air batteries are considered as the most promising candidate for the power source of electric vehicles(EVs) due to their high energy density. However, the practical application of metal-air batteries is still challenging. In the past decade, many strategies have been purposed and explored, which promoted the development of metal-air batteries. The reaction mechanisms have been gradually clarified and catalysts have been rationally designed for air cathodes. In this review, we summarize the recent development of alkali metal-air batteries from four parts: metal anodes, electrolytes, air cathodes and reactant gases, wherein we highlight the important achievement in this filed. Finally problems and prospective are discussed towards the future development of alkali metal-air batteries.

Anode reaction mechanisms of Na|NaCl-CaCl2|Zn liquid metal battery

Na|NaCl-CaCl_(2)|Zn liquid metal battery is regarded as a promising energy storage system for power grids.Despite intensive attempts to present a real mechanism of metal electrodes reaction, those for Na||Zn LMBs are not clear yet. Herein, the anode reactions for the multiple discharge potential plateaus were deduced by means of FactSage thermochemical software, which were subsequently validated by X-ray diffraction analysis and the modeling of phase transformation in the cooling process. A pre-treatment process was proposed for the analysis of anode product composition using the atomic absorption spectrometry method, and the anode states at working temperature(560 ℃) were obtained by the Na-CaZn ternary phase for the first time. The results indicate the discharge of Na and Ca led to the formation of Ca-Zn intermetallic compounds, whilst the extraction of Ca in Ca-Zn intermetallic compounds was responsible for the multiple discharge plateaus. Moreover, it was found that the charging product was in electrochemical double liquid metal layers, which are composed of Na and Ca with dissolved Zn respectively.

Self-discharge mitigation in a liquid metal displacement battery

Recently,a disruptive idea was reported about the discovery of a new type of battery named Liquid Displacement Battery(LDB)comprising liquid metal electrodes and molten salt electrolyte.This cell featured a novel concept of a porous electronically conductive faradaic membrane instead of the traditional ion-selective ceramic membrane.LDBs are attractive for stationary storage applications but need mitigation against self-discharge.In the instant battery chemistry,Li|LiCl-PbCl_(2)|Pb,reducing the diffusion coefficient of lead ions can be a way forward and a solution can be the addition of Pb O to the electrolyte.The latter acts as a supplementary barrier and complements the function of the faradaic membrane.The remedial actions improved the cell’s coulombic efficiency from 92%to 97%without affecting the voltage efficiency.In addition,the limiting current density of a 500 m Ah cell increased from 575 to 831 m A cm;and the limiting power from 2.53 to 3.66 W.Finally,the effect of Pb O on the impedance and polarization of the cell was also studied.

Nanoconfinement effect of nanoporous carbon electrodes for ionic liquid-based aluminum metal anode

Rechargeable aluminum batteries(RABs),which use earth-abundant and high-volumetric-capacity metal anodes(8040 m Ah cm-3),have great potential as next-generation power sources because they use cheaper resources to deliver higher energies,compared to current lithium ion batteries.However,the mechanism of charge delivery in the newly developed,ionic liquid-based electrolytic system for RABs differs from that in conventional organic electrolytes.Thus,targeted research efforts are required to address the large overpotentials and cycling decay encountered in the ionic liquid-based electrolytic system.In this study,a nanoporous carbon(NPC)electrode with well-developed nanopores is used to develop a high-performance aluminum anode.The negatively charged nanopores can provide quenched dynamics of electrolyte molecules in the aluminum deposition process,resulting in an increased collision rate.The fast chemical equilibrium of anionic species induced by the facilitated anionic collisions leads to more favorable reduction reactions that form aluminum metals.The nanoconfinement effect causes separated nucleation and growth of aluminum nanoparticles in the multiple confined nanopores,leading to higher coulombic efficiencies and more stable cycling performance compared with macroporous carbon black and 2D stainless steel electrodes.

Advances on Na-K liquid alloy-based batteries

Sodium-potassium(Na^(-)K)liquid alloys attract increasing research attention,as an ideal alternative of Li metal for metal-based batteries,attributing to their high abundance,low redox potential,high capacity,and dendrite-free properties.In addition,the liquid and self-healing features of Na^(-)K alloys endow good electrode/electrolyte interfacial contact.The recent advances on the Na^(-)K liquid alloy-based batteries(NKBs)are reviewed herein.The anode designs for immobilization of the liquid alloy are introduced.The influences of the electrolyte and cathode materials on the battery performances are discussed.In addition,considering the co-existence of both K^(+)and Na^(+)in the electrolyte,the working mechanisms of the NKBs are elaborated.We also show that despite the improvement,challenges of the NKBs remain.The compatibility between Na^(-)K liquid alloy and electrolyte,as well as disputed working mechanisms,request detailed surface analyses of the liquid alloy and local element distribution evolution in the battery.This review would shed light on the fundamental understanding of Na^(-)K alloy electrochemistry and the development of dendrite-free metal-based energy storage systems with high energy density.

Liquid metal as an efficient protective layer for lithium metal anodes in all-solid-state batteries

Lithium metal batteries with inorganic solid-state electrolytes have emerged as strong and attractive candidates for electrochemical energy storage devices because of their high-energy content and safety.Nonetheless,inherent challenges of deleterious lithium dendrite growth and poor interfacial stability hinder their commercial application.Herein,we report a liquid metal-coated lithium metal(LM@Li)anode strategy to improve the contact between lithium metal and a Li6PS5Cl inorganic electrolyte.The LM@Li symmetric cell shows over 1000 h of stable lithium plating/stripping cycles at 2mA cm^(-2) and a significantly higher critical current density of 9.8 mAcm^(-2) at 25°C.In addition,a full battery assembled with a high-capacity composite LiNbO3@-LiNi_(0.7)Co_(0.2)Mn_(0.1)O_(2)(LNO@NCM721)cathode shows stable cycling performance.Experimental and computational results have demonstrated that dendrite growth tolerance and physical contact in solid-state batteries can be reinforced by using LM interlayers for interfacial modification.

储能电池建模与状态估计研究进展

储能电池具有能够平滑可再生能源输出,提高电力系统灵活性和应对电力需求峰谷等优势,有助于推动可再生能源发展,从而应对环境污染和能源紧缺的双重压力。目前市场主流的储能电池为锂离子电池,具有高比能特性,同时新型储能电池也在蓬勃发展,其中全钒液流电池具有高安全性的优势,液态金属电池具有超长循环寿命,在电力储能领域具有重要应用前景。储能电池的建模和状态估计对提高储能电池系统性能,确保其安全性以及优化维护效率至关重要,因此文中对锂离子电池、全钒液流电池和液态金属电池的建模和状态估计进行综述。首先,介绍了储能电池状态估计的整体框架,对基于实验的方法、基于模型的方法和基于数据驱动的方法进行整体介绍,并对荷电状态(state of charge,SOC)、健康状态(state of health,SOH)和剩余使用寿命(remaining useful life,RUL)进行概括;然后,从原理出发,分别总结了不同储能电池体系的内部工作过程、模型构建、状态估计与电池管理过程;最后,对不同储能电池体系的主要工作特性进行横向对比和总结,旨在为储能电池选择和发展提供启示。