Eutectic-Based Polymer Electrolyte with the Enhanced Lithium Salt Dissociation for High-Performance Lithium Metal Batteries

The deployment of lithium metal anode in solid-state batteries with polymer electrolytes has been recognized as a promising approach to achieving high-energy-density technologies. However, the practical application of the polymer electrolytes is currently constrained by various challenges, including low ionic conductivity, inadequate electrochemical window, and poor interface stability. To address these issues, a novel eutectic-based polymer electrolyte consisting of succinonitrile (SN) and poly (ethylene glycol) methyl ether acrylate (PEGMEA) is developed. The research results demonstrate that the interactions between SN and PEGMEA promote the dissociation of the lithium difluoro(oxalato) borate (LiDFOB) salt and increase the concentration of free Li⁺. The well-designed eutectic-based PAN_1.2-SPE (PEGMEA: SN=1: 1.2 mass ratio) exhibits high ionic conductivity of 1.30 mS cm⁻¹ at 30 °C and superior interface stability with Li anode. The Li/Li symmetric cell based on PAN_1.2-SPE enables long-term plating/stripping at 0.3 and 0.5 mA cm⁻², and the Li/LiFePO₄ cell achieves superior long-term cycling stability (capacity retention of 80.3 % after 1500 cycles). Moreover, Li/LiFePO₄ and Li/LiNi_0.6Co_0.2Mn_0.2O₂ pouch cells employing PAN_1.2-SPE demonstrate excellent cycling and safety characteristics. This study presents a new pathway for designing high-performance polymer electrolytes and promotes the practical application of high-stable lithium metal batteries.     

Electron Delocalization Enables Sulfone-based Single-solvent Electrolyte for Lithium Metal Batteries

Li-metal batteries (LMB), although providing high energy density, face the grand challenge of identifying good electrolyte solvents for cycling. Common solvents are either only stable against lithium metal anode or only stable against LiNi_xMn_yCo_1-x-yO₂ (NMC) cathode. There is significant effort trying to increase the cathode stability for ether electrolytes, which are in general stable against lithium metal anode. In comparison, there is much less effort trying to increase the anode stability of electrolytes that are stable against NMC cathode. One example is the sulfone-based electrolyte. It has good cathode stability but is hindered from practical application because of (1) high viscosity and poor wetting capability and (2) poor anode stability. Here, we solve these issues by modifying the sulfone molecules using resonance and electron withdrawing effect. The viscosity is significantly reduced by delocalizing the electrons through introducing additional oxygen on the molecular backbone and applying appropriate fluorination. The resulting molecule 2,2,2-trifluoroethyl mesylate (TFEM) has decreased Lewis basicity and less reactivity toward Li⁺. The electrolyte based on TFEM as single solvent enables cycling of LMB under harsh conditions of low N/P ratio (21 mg/cm² NMC811 and 50 μm Li) with 90 % capacity retention after 160 cycles at C/3 discharge rate.     

Nitriding‐Interface‐Regulated Lithium Plating Enables Flame‐Retardant Electrolytes for High‐Voltage Lithium Metal Batteries

Safety concerns are impeding the applications of lithium metal batteries. Flame‐retardant electrolytes, such as organic phosphates electrolytes (OPEs), could intrinsically eliminate fire hazards and improve battery safety. However, OPEs show poor compatibility with Li metal though the exact reason has yet to be identified. Here, the lithium plating process in OPEs and Li/OPEs interface chemistry were investigated through ex situ and in situ techniques, and the cause for this incompatibility was revealed to be the highly resistive and inhomogeneous interfaces. Further, a nitriding interface strategy was proposed to ameliorate this issue and a Li metal anode with an improved Li cycling stability (300 h) and dendrite‐free morphology is achieved. Meanwhile, the full batteries coupled with nickel‐rich cathodes, such as LiNi_0.8Co_0.1Mn_0.1O₂, show excellent cycling stability and outstanding safety (passed the nail penetration test). This successful nitriding‐interface strategy paves a new way to handle the incompatibility between electrode and electrolyte.     

Hybrid Sub-1 nm Nanosheets of Co-assembled MnZnCuOx and Polyoxometalate Clusters as Anodes for Li-ion Batteries

Transition metal oxide (TMO) anode materials in lithium-ion batteries (LIBs) usually suffer from serious volume expansion leading to the pulverization of structures, further giving rise to lower specific capacity and worse cycling stability. Herein, by introducing polyoxometalate (POM) clusters into TMOs and precisely controlling the amount of POMs, the MnZnCuO_x-phosphomolybdic acid hybrid sub-1 nm nanosheets (MZC-PMA HSNSs) anode is successfully fabricated, where the special electron rich structure of POMs is conducive to accelerating the migration of lithium ions on the anode to obtain higher specific capacity, and the non-covalent interactions between POMs and TMOs make the HSNSs possess excellent structural and chemical stability, thus exhibiting outstanding electrochemical performance in LIBs, achieving a high reversible capacity (1157 mAh g⁻¹ at 100 mA g⁻¹) and an admirable long-term cycling stability at low and high current densities.     

Electrochemical lithium extraction from β-lithium nitride

In this paper we report the electrochemical characterization of mixtures of ball-milled lithium nitride and iron metal. Several samples were prepared with different lithium nitride to iron molar ratios. X-ray diffraction (XRD) spectra showed the presence of iron metal in all the samples and β-lithium nitride in the samples with higher Li₃N/Fe ratio. No evidence of other phases was detected. The milled powders were used to prepare composite cathodes for the electrochemical characterization. It was found that lithium can be extracted from the materials at a flat potential of 1.2 V vs. Li. The sample with Li₃N/Fe molar ratio 8:1 showed the highest specific capacity (1125 mAh g⁻¹) corresponding to the extraction of 1.8 Li equivalents per mole of lithium nitride. Only a fraction of the lithium extracted was re-inserted in the following discharge cycle. A drastic reduction of the capacity was observed for all the samples on further cycling. An enhancement of the cyclability was obtained by lowering the end-charge voltage that resulted in a reduction of the lithium extracted. The lithium extraction/insertion process was characterized by a large voltage difference indicating that the reaction is largely irreversible.     

热压法构筑锂负极聚偏氟乙烯基双功能保护层的研究

锂金属具有高比容量(3860 mA·h/g)和低电化学电位(-3.04 V vs. SHE), 是一种极具潜力的新型电池负极材料. 然而, 锂金属电化学稳定性差, 导致电池循环寿命受限, 容易产生枝晶, 造成电池短路, 引发安全风险, 而其对空气及环境的高度敏感性也极大增加了电池制作的难度与成本, 限制了其应用推广. 改善锂金属负极的界面稳定性被认为是提升锂金属电池性能的重要途径. 本文通过简单直接的热压法在锂金属负极表面构筑了聚偏氟乙烯(PVDF)基双功能保护层, 使锂金属的空气稳定性提升至约120 min, 并延长了锂金属对称电池的循环寿命至约1200 h; 再通过在PVDF保护层内引入亲锂的SnO₂粒子, 形成的无机有机复合保护层可以通过原位合金化反应提供锂沉积的形核位点, 在保持良好循环稳定性的基础上进一步降低成锂沉积的过电位, 极化过电位从0.016 V降低到0.007 V. 含有该保护层的全电池展现出约200次的长循环寿命与90%以上的高容量保持率, 在3C高倍率下放电比容量仍达127 mA·h/g. 提出的双功能电极界面保护层策略能有效提升锂金属负极空气稳定性和电化学性能.     

Graphene-supported cobalt nanoparticles used to activate SiO2-based anode for lithium-ion batteries

Although SiO₂-based anode is a strong competitor to supersede graphite anode for lithium-ion batteries, it still has problems such as low electrochemical activity, enormous loss of active lithium, and serious volume expansion. In order to solve these problems, we used a graphene network loaded with cobalt metal nanoparticles (rGO–Co) to coat SiO₂ porous hollow spheres (SiO₂@rGO–Co). The construction of porous hollow structure and graphene network can shorten the lithium-ion (Li⁺) diffusion distance and enhance the conductivity of the composite, which improves the electrochemical activity of SiO₂ effectively. They also alleviate the volume expansion of the anode in the cycling process. Moreover, nano-scale cobalt metal particles dispersed on graphene catalyze the conversion reaction of SiO₂ and activate the locked Li⁺ in Li₂O through a reversible reaction, which improves the charge and discharge capacity of the anode. The capacity of SiO₂@rGO–Co reaches 370.4 mAh/g after 100 cycles at 0.1 A/g, which is 6.19 times the capacity of pure SiO₂ (59.8 mAh/g) under the same circumstance. What is more, its structure also exhibits excellent cycle stability, with a volume expansion rate of only 13.0% after 100 cycles at a current density of 0.1 A/g.     

The Li ion transport behavior in the defect graphene composite Li3N SEI: a first-principle calculation

An artificial solid electrolyte interface (SEI) of a graphene composite lithium salt can inhibit the growth of dendrites by driving the lithium deposition behavior on the surface of the lithium metal anode. The first-principle method was used to calculate the graphene/lithium nitride SEI, including the structural form and stability of intrinsic (G-Li₃N), single-vacancy defect (SVG-Li₃N), and double-vacancy defect (DVG-Li₃N) graphene heterostructure. The adsorption and migration behavior of lithium ions on the heterostructure surface and the interface were also calculated. This study showed that the modification of double-vacancy defect graphene improved the stability of the heterostructure, and the adhesion work of the composite SEI is the highest. The modification of defective graphene increases the adsorption energy of lithium atoms on the surface and interface of the heterostructure: the strongest adsorption of Li atoms on the single-vacancy defect region of the heterostructure, the opposition migration pathway of Li atoms on the surface and interface of the DVG-Li₃N heterostructure, and the decrease diffusion energy of Li atoms on the surface and interface of the DVG-Li₃N heterostructure. A composite layered SEI of graphene and Li₃N was constructed to inhibit dendritic growth by adjusting the deposition behavior of lithium atoms.     

金属锂在含(亚)硫酰基添加剂电解液中电化学可逆性研究

分别以亚硫酰氯(SOCl2)、硫酰氯(SO2Cl2)、二甲亚砜(DMSO)、苯磺酰氯(BSC)和苯基乙烯基亚砜(PVSO)作为添加剂, 加入至1 mol•L－1 LiPF6/碳酸乙烯酯(EC)＋碳酸二甲酯(DMC)(体积比为1∶1)电解液中, 采用恒电流沉积-溶出法、循环伏安法(CV)、电化学阻抗谱(EIS)、X射线光电子能谱(XPS)测试技术, 研究了添加剂对电化学金属锂沉积-溶出可逆性以及金属锂负极/电解液界面性质的影响. 电化学测试结果表明, 添加SO2Cl2和BSC能显著改善金属锂电极的循环性能, 100% DOD(锂全溶出)条件下, 循环效率稳定在90%左右. 电化学测试、添加剂分子电子亲和能计算并结合XPS测试结果表明, 较早反应成膜的SO2Cl2和BSC添加剂可以在一定程度上抑制电解液溶剂的分解, 使锂电极循环效率和寿命得以提高. 洞察和比较添加剂的结构揭示, 含磺酰基的化合物明显优于含亚磺酰基的化合物.     

Ultraviolet-Cured Semi-Interpenetrating Network Polymer Electrolytes for High-Performance Quasi-Solid-State Lithium Metal Batteries

Solid polymer electrolytes with relatively low ionic conductivity at room temperature and poor mechanical strength greatly restrict their practical applications. Herein, we design semi-interpenetrating network polymer (SNP) electrolyte composed of an ultraviolet-crosslinked polymer network (ethoxylated trimethylolpropane triacrylate), linear polymer chains (polyvinylidene fluoride-co-hexafluoropropylene) and lithium salt solution to satisfy the demand of high ionic conductivity, good mechanical flexibility, and electrochemical stability for lithium metal batteries. The semi-interpenetrating network has a pivotal effect in improving chain relaxation, facilitating the local segmental motion of polymer chains and reducing the polymer crystallinity. Thanks to these advantages, the SNP electrolyte shows a high ionic conductivity (1.12 mS cm⁻¹ at 30 °C), wide electrochemical stability window (4.6 V vs. Li⁺/Li), good bendability and shape versatility. The promoted ion transport combined with suppressed impedance growth during cycling contribute to good cell performance. The assembled quasi-solid-state lithium metal batteries (LiFePO₄/SNP/Li) exhibit good cycling stability and rate capability at room temperature.     

Facile simultaneous polymerization enabled in-situ confinement of size-tailored GeO2 nanocrystals in continuous S-Doped carbons for lithium storage

GeO₂ is a promising anode material for lithium ion batteries due to its high theoretical capacity (1126 mAh g^?1 for reversibly storing 4.4 Li⁺), and moderately low operating voltage (<1.5 V). Nevertheless, the fabrication of truly durable GeO₂ anode with satisfactory rate capability and cycling stability remains a big challenge because of its inherent low conductivity, and the large volume expansion upon charge-discharge that causes severe capacity fading. In this study, an innovative nanostructure with size-adjustable GeO₂ nanoparticles (16–26 nm) embedded in continuous S-doped carbon (GeO₂/S-doped carbon, GSC) has been successfully fabricated via a facile in-situ simultaneous polymerization method followed by heat treatment. The electrochemical results indicate that the as-prepared GSC composites show high reversible capacity (672.9 mAh g^?1 at 50 mA g^?1), superior rate capability (332.9 mAh g^?1 at 1000 mA g^?1), and long-term cycle life (179 mAh g^?1 after 500 cycles at 1000 mA g^?1) as anode materials for lithium ion batteries. The excellent electrochemical performance of GSC nanocomposites could be ascribed to the homogeneous and continuous S-doped carbon matrix, which provides shortened ion diffusion pathway, increased electrical conductivity, enhanced structural stability, and introduced surface/interface property.     

Studies on the effects of coated Li2CO3 on lithium electrode

Although a lithium metal anode has a high energy density compared with a carbon insertion anode, the poor rechargeability prevents the practical use of anode materials. A lithium electrode coated with Li₂CO₃ was prepared as a negative electrode to enhance cycleability through the control of the solid electrolyte interface (SEI) layer formation in Li secondary batteries. The electrochemical characteristics of the SEI layer were examined using chronopotentiometry (CP) and impedance spectroscopy. The Li₂CO₃-SEI layer prevents electrolyte decomposition reaction and has low interface resistance. In addition, the lithium ion diffusion in the SEI layer of the uncoated and the Li₂CO₃-coated electrode was evaluated using chronoamperometry (CA).     

Unlocking Reversible Silicon Redox for High-Performing Chlorine Batteries

Chlorine (Cl)-based batteries such as Li/Cl₂ batteries are recognized as promising candidates for energy storage with low cost and high performance. However, the current use of Li metal anodes in Cl-based batteries has raised serious concerns regarding safety, cost, and production complexity. More importantly, the well-documented parasitic reactions between Li metal and Cl-based electrolytes require a large excess of Li metal, which inevitably sacrifices the electrochemical performance of the full cell. Therefore, it is crucial but challenging to establish new anode chemistry, particularly with electrochemical reversibility, for Cl-based batteries. Here we show, for the first time, reversible Si redox in Cl-based batteries through efficient electrolyte dilution and anode/electrolyte interface passivation using 1,2-dichloroethane and cyclized polyacrylonitrile as key mediators. Our Si anode chemistry enables significantly increased cycling stability and shelf lives compared with conventional Li metal anodes. It also avoids the use of a large excess of anode materials, thus enabling the first rechargeable Cl₂ full battery with remarkable energy and power densities of 809 Wh kg⁻¹ and 4,277 W kg⁻¹, respectively. The Si anode chemistry affords fast kinetics with remarkable rate capability and low-temperature electrochemical performance, indicating its great potential in practical applications.     

Asymmetric double-layer composite electrolyte with enhanced ionic conductivity and interface stability for all-solid-state lithium metal batteries

All-solid-state Li metal battery has been regarded as a promising battery technology due to its high energy density based on the high capacity of lithium metal anode and high safety based on the all solid state electrolyte without inflammable solvent.However,challenges still exist mainly in the poor contact and unstable interface between electrolyte and electrodes.Herein,we demonstrate an asymmetric design of the composite polymer electrolyte with two different layers to overcome the interface issues at both the cathode and the anode side simultaneously.At the cathode side,the polypropylene carbonate layer has enough viscosity and flexibility to reduce the inter-facial resistance,while at the Li anode side,the polyethylene oxide layer modified with hexagonal boron nitride has high mechanical strength to suppress the Li dendrite growth.Owing to the synergetic effect between different components,the asprepared double layer composite polymer electrolyte demonstrates a large electrochemical window of5.17 V,a high ionic conductivity of 6.1×10~(-4) S/cm,and a transfe rence number of 0.56,featuring excellent ion transport kinetics and good chemical stability.All-solid-state Li metal battery assembled with LiFePO_4 cathode and Li anode delivers a high capacity of 150.9 mAh/g at 25℃ and 0.1 C-rate,showing great potential for practical applications.     

Metal–Organic Frameworks-Derived Mesoporous Si/SiOx@NC Nanospheres as a Long-Lifespan Anode Material for Lithium-Ion Batteries

Silicon (Si)-based anode materials with suitable engineered nanostructures generally have improved lithium storage capabilities, which provide great promise for the electrochemical performance in lithium-ion batteries (LIBs). Herein, a metal–organic framework (MOF)-derived unique core–shell Si/SiO_x@NC structure has been synthesized by a facile magnesio-thermic reduction, in which the Si and SiO_x matrix were encapsulated by nitrogen (N)-doped carbon. Importantly, the well-designed nanostructure has enough space to accommodate the volume change during the lithiation/delithiation process. The conductive porous N-doped carbon was optimized through direct carbonization and reduction of SiO₂ into Si/SiO_x simultaneously. Benefiting from the core–shell structure, the synthesized product exhibited enhanced electrochemical performance as an anode material in LIBs. Particularly, the Si/SiO_x@NC-650 anode showed the best reversible capacities up to 724 and 702 mAh g⁻¹ even after 100 cycles. The excellent cycling stability of Si/SiO_x@NC-650 may be attributed to the core–shell structure as well as the synergistic effect between the Si/SiO_x and MOF-derived N-doped carbon.     

Investigation of Water-Soluble Binders for LiNi0.5Mn1.5O4-Based Full Cells

Two water-soluble binders of carboxymethyl cellulose (CMC) and sodium alginate (SA) have been studied in comparison with N-methylpyrrolidone-soluble poly(vinylidene difluoride–co-hexafluoropropylene) (PVdF-HFP) to understand their effect on the electrochemical performance of a high-voltage lithium nickel manganese oxide (LNMO) cathode. The electrochemical performance has been investigated in full cells using a Li₄Ti₅O₁₂ (LTO) anode. At room temperature, LNMO cathodes prepared with aqueous binders provided a similar electrochemical performance as those prepared with PVdF-HFP. However, at 55 °C, the full cells containing LNMO with the aqueous binders showed higher cycling stability. The results are supported by intermittent current interruption resistance measurements, wherein the electrodes with SA showed lower resistance. The surface layer formed on the electrodes after cycling has been characterized by X-ray photoelectron spectroscopy. The amount of transition metal dissolutions was comparable for all three cells. However, the amount of hydrogen fluoride (HF) content in the electrolyte cycled at 55 °C is lower in the cell with the SA binder. These results suggest that use of water-soluble binders could provide a practical and more sustainable alternative to PVdF-based binders for the fabrication of LNMO electrodes.     

Constructing Co3O4 Nanowires on Carbon Fiber Film as a Lithiophilic Host for Stable Lithium Metal Anodes

Lithium metal has been considered as the most promising anode electrode for substantially improving the energy density of next‐generation energy storage devices. However, uncontrollable lithium dendrite growth, an unstable solid electrolyte interface (SEI), and infinite volume variation severely shortens its service lifespan and causes safety hazards, thus hindering the practical application of lithium metal electrodes. Here, carbon fiber film (CFF) modified by lithiophilic Co₃O₄ nanowires (denoted as Co₃O₄ Nws) was proposed as a matrix for prestoring lithium metal through a thermal infusion method. The homogeneous needle‐like Co₃O₄ nanowires can effectively promote molten lithium to infiltrate into the CFF skeleton. The post‐formed Co?Li₂O nanowires produced by the reaction of Co₃O₄ Nws and molten lithium can homogeneously distribute lithium ions flux and efficaciously increase the adsorption energy with lithium ions proved by density functional theory (DFT) calculation, boosting a uniform lithium deposition without dendrite growth. Therefore, the obtained composite anode (denoted as CFF/Co?Li₂O@Li) exhibits superior electrochemical performance with high stripping/plating capacities of 3 mAh cm^?2 and 5 mAh cm^?2 over long‐term cycles in symmetrical batteries. Moreover, in comparison with bare lithium anode, superior Coulombic efficiencies coupled with copper collector and full battery behaviors paired with LiFePO₄ cathode are achieved when CFF/Co?Li₂O@Li composite anode was employed.     

A Liquid/Liquid Electrolyte Interface that Inhibits Corrosion and Dendrite Growth of Lithium in Lithium‐Metal Batteries

A proof‐of‐concept study on a liquid/liquid (L/L) two‐phase electrolyte interface is reported by using the polarity difference of solvent for the protection of Li‐metal anode with long‐term operation over 2000 h. The L/L electrolyte interface constructed by non‐polar fluorosilicane (PFTOS) and conventionally polar dimethyl sulfoxide solvents can block direct contact between conventional electrolyte and Li anode, and consequently their side reactions can be significantly eliminated. Moreover, the homogeneous Li‐ion flow and Li‐mass deposition can be realized by the formation of a thin and uniform solid‐electrolyte interphase (SEI) composed of LiF, Li_xC, Li_xSiO_y between PFTOS and Li anode, as well as the super‐wettability state of PFTOS to Li anode, resulting in the suppression of Li dendrite formation. The cycling stability in a lithium–oxygen battery as a model is improved 4 times with the L/L electrolyte interface.     

Processable and Moldable Sodium‐Metal Anodes

Sodium‐ion batteries are similar in concept and function to lithium‐ion batteries, but their development and commercialization lag far behind. One obstacle is the lack of a standard reference electrode. Unlike Li foil reference electrodes, sodium is not easily processable or moldable and it deforms easily. Herein we fabricate a processable and moldable composite Na metal anode made from Na and reduced graphene oxide (r‐GO). With only 4.5 % percent r‐GO, the composite anodes had improved hardness, strength, and stability to corrosion compared to Na metal, and can be engineered to various shapes and sizes. The plating/stripping cycling of the composite anode was significantly extended in both ether and carbonate electrolytes giving less dendrite formation. We used the composite anode in both Na‐O₂ and Na‐Na₃V₂(PO₄)₃ full cells.     

石榴石固体电解质Li3BO3界面改性研究

石榴石固体电解质由于其高的离子电导率,对锂金属稳定等优点成为了下一代高性能锂电池的重要研究方向之一.但锂金属负极界面浸润性与锂枝晶问题限制了其应用.本文通过简单的液相沉积结合高温烧结的方法,在石榴石固体电解质片表面构建了一层稳定的硼酸三锂(Li3BO3)修饰层.研究表明,Li3BO3 修饰层可以有效改善石榴石固体电解质...