Synthesis of lithium metal silicates for lithium ion batteries

Synthesis strategies, nanostructures, and different electrochemical performances are prominent features of rechargeable batteries. Three types Li₂MSiO₄ cathode metarials for lithium ion batteries:Li₂FeSiO₄, Li₂MnSiO₄, and Li₂CoSiO₄ are scientifically discussed, and the comprehensive summaries and evaluations are given in this review.     

Integrated lithium metal anode protected by composite solid electrolyte film enables stable quasi-solid-state lithium metal batteries

Lithium (Li) metal, possessing an extremely high theoretical specific capacity (3860 mAh/g) and the most negative electrode potential (−3.040 V vs. standard hydrogen electrode), is one the most favorable anode materials for future high-energy-density batteries. However, the poor cyclability and safety issues induced by extremely unstable interfaces of traditional liquid Li metal batteries have limited their practical applications. Herein, a quasi-solid battery is constructed to offer superior interfacial stability as well as excellent interfacial contact by the incorporation of Li@composite solid electrolyte integrated electrode and a limited amount of liquid electrolyte (7.5 μL/cm²). By combining the inorganic garnet Al-doped Li_6.75La₃Zr_1.75Ta_0.25O₁₂ (LLZO) with high mechanical strength and ionic conductivity and the organic ethylene-vinyl acetate copolymer (EVA) with good flexibility, the composite solid electrolyte film could provide sufficient ion channels, sustained interfacial contact and good mechanical stability at the anode side, which significantly alleviates the thermodynamic corrosion and safety problems induced by liquid electrolytes. This innovative and facile quasi-solid strategy is aimed to promote the intrinsic safety and stability of working Li metal anode, shedding light on the development of next-generation high-performance Li metal batteries.     

Constructing a uniform lithium iodide layer for stabilizing lithium metal anode

The metallic lithium(Li)is the ultimate option in the development of anodes for high-energy secondary batteries.Unfortunately,inferior cycling reversibility and Li dendrites growth of Li metal as anode enormously impede its commercialization.Here,a uniform Li I protective layer is constructed on Li metal anode via a facile and direct solid-gas reaction of Li metal with iodine vapor.The pre-constructed Li I layer possesses more steadily and faster Li ion transport than the conventional SEI layer and contributes to a steady interface for the Li metal anode,which affords a smooth Li deposition morphology without Li dendrites formation.The symmetrical cell with the Li metal anode protected by Li I layer exhibits a longer cycling lifetime of over 700 h at a current density of 1 m A cm^-2 with Li plating capacity of 1 m Ah cm^-2.Moreover,the Li I layer protected Li metal anode can still remain high capacity retention of 74.6%after 500 cycles in the full cell paired with NCM523 cathode.The work proposes an easy and effective method to fabricate a uniform and stable protective layer on the Li metal anode and offers a practicable thinking for the commercial implementation of Li metal batteries.     

Tunable lithium storage properties of metal lithium titanates by stoichiometric modulation

A simple stoichiometric modulation of Na_2 − 2xSr_xLi₂Ti₆O₁₄ was developed to achieve tunable electrochemical properties of the material. The concept was confirmed experimentally and theoretically using density functional theory (DFT) calculations. Both the operating potential and the amount of reversibly intercalated lithium ions were manipulated by simply changing the Na/Sr ratio. These unique characteristics originated from a gradual change in the electron density on the Ti atoms and the extra lithium insertion sites at SrLi₂Ti₆O₁₄. As a promising anode material for lithium-ion batteries, Na_2 − 2xSr_xLi₂Ti₆O₁₄ and its tunable electrochemical properties have significant importance in terms of the development of tailored electrodes with desirable electrochemical performance.     

A cation-dipole-reinforced elastic polymer electrolyte enabling long-cycling quasi-solid-state lithium metal batteries

The application of ionic liquids(IL) in polymer electrolytes represents a safer alternative to the currently used organic solvents in lithium batteries due to their nonflammability and thermal stability. However, as a plasticizer, it is generally agreed that the introduction of ionic liquid usually leads to a trade-off between ion transport and mechanical properties of polymer electrolyte. Here we report the synthesis of an IL-embedded polymer electrolyte with both high ionic conductivity(2.77 ×...     

A two-dimension laminar composite protective layer for dendrite-free lithium metal anode

Lithium(Li)metal anodes with the high theoretical specific capacity(3860 mAh g^-1)and most negative reduction potential(-3.04 V vs.standard hydrogen electrode)have been considered as an ultimate choice for energy storage devices with high energy density[1-4].However,the practical applications of Li metalbased batteries(LMBs)are confronted with two tough issues:Li dendrite growth induced by uneven Li depositions and unstable solid electrolyte interphase(SEI)(Fig.1a)[5,6].     

A solid lithium electrolyte via addition of lithium isopropoxide to a metal-organic framework with open metal sites

The uptake of LiO(i)Pr in Mg(2)(dobdc) (dobdc(4-) = 1,4-dioxido-2,5-benzenedicarboxylate) followed by soaking in a typical electrolyte solution leads to the new solid lithium electrolyte Mg(2)(dobdc)·0.35LiO(i)Pr·0.25LiBF(4)·EC·DEC (EC = ethylene carbonate; DEC = diethyl carbonate). Two-point ac impedance data show a pressed pellet of this material to have a conductivity of 3.1 × 10(-4) S/cm at 300 K. In addition, the results from variable-temperature measurements reveal an activation energy of just 0.15 eV, while single-particle data suggest that intraparticle transport dominates conduction.     

Protection of lithium metal surfaces using chlorosilanes

In this paper, we present a new approach for protecting metallic lithium surfaces based on a reaction between the thin native layer of lithium hydroxide present on the surface and various chlorosilane derivatives. The chemical composition of the resulting layer and the chemistry involved in layer formation were analyzed by polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDX). Spectroscopy shows the disappearance of surface hydroxide groups and the appearance of silicon and chloride on the lithium surface. Differential scanning calorimetry (DSC) and electrochemical impedance spectroscopy (EIS) show that this surface treatment protects the lithium from certain gas-phase reactions and is ionically conductive.     

Trace analysis of lithium metal by PIXE

A rapid method is described for simultaneous trace determination of metallic impurities in lithium metal by Particle Induced X-ray Emission (PIXE) technique. The impurities were preconcentrated by ion-exchange separation using a weak cation exchanger, Bio Rex-70 and analyzed by 2.34 MeV protons. The reliability of the method was tested by analyzing synthetic samples having several metallic impurities at 1–5 ppm range.     

Designing composite solid-state electrolytes for high performance lithium ion or lithium metal batteries

Solid-state electrolytes (SSEs) are capable of inhibiting the growth of lithium dendrites, demonstrating great potential in next-generation lithium-ion batteries (LIBs). However, poor room temperature ionic conductivity and the unstable interface between SSEs and the electrode block their large-scale applications in LIBs. Composite solid-state electrolytes (CSSEs) formed by mixing different ionic conductors lead to better performance than single SSEs, especially in terms of ionic conductivity and interfacial stability. Herein, we have systematically reviewed recent developments and investigations of CSSEs including inorganic composite and organic–inorganic composite materials, in order to provide a better understanding of designing CSSEs. The comparison of different types of CSSEs relative to their parental materials is deeply discussed in the context of ionic conductivity and interfacial design. Then, the proposed ion transfer pathways and models of lithium dendrite growth in composites are outlined to inspire future development of CSSEs.

Composite solid-state electrolytes (CSSEs) formed by mixing different ionic conductors lead to better performance than a single solid-state electrolytes (SSEs), demonstrating great potentials in the next-generation lithium-ion batteries (LIBs).     

Porous conductive interlayer for dendrite-free lithium metal battery

Lithium(Li) metal,possessing ultrahigh theoretical capacity and the lowest electrode potential,is regarded as a promising new generation anode material.However,the uncontrollable growth of Li dendrites during cycling process gives rise to problems as capacity decay and short circuit,suppressing the cycling and safety performances of Li metal battery.In this contribution,porous conductive interlayer(PCI),composed of carbon nanofibers(CNFs) and polyisophthaloyl metaphenylene diamine(PMIA),is developed to suppress Li dendrites and stabilize Li metal anode.PCI possesses the excellent conductive ability of CNFs and the preeminent mechanical properties of PMIA at the same time.When Li metal contacts with PCI during cycling process,an equipotential surface forms on their interface,which eliminates the tip effect on Li anode and homogenizes Li-ions flux in combination with the uniform porous structure of PCI.Employed PCI,the Li|Cu cell exhibits a remarkable cycling stability with a high average Coulombic efficiency of 97.5% for 100 cycles at 0.5 mA cm^-2.And the Li|LiFePO_4 cell exhibits improved rate capability(114.7 mAh g^-1 at 5.0 C) and enhanced cycling performance(78.9% capacity retention rate over 500 cycles at 1.0 C).This work provides a fresh and effective solving strategy for the problem of dendrites in Li metal battery.     

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 li...     

Recent progress in lithium-ion and lithium metal batteries

Moving towards carbon-free energy and global commercialization of electric vehicles stimulated extensive development in the field of lithium-ion batteries (LIBs), and to date, many scientific and technological advances have been achieved. The number of research works devoted to developing high-capacity and stable materials for lithium- ion and lithium metal batteries (LMBs) is constantly rising. This review covers the main progress in the development of LIBs and LMBs based on research works published in 2021. One of the main goals in the recent publications is to solve the problem of instability of layered nickel-rich lithium– nickel–cobalt–manganese oxides (Ni-rich NMC) cathodes, as well as silicon anodes. Improving the stability of NMC cathodes can be achieved by doping them with cations as well as by coating the oxides’ surfaces with protective layers (organic polymers and inorganic materials). The most effective strategies for dampening volumetric changes in silicon anodes include using porous silicon structures, obtaining composites with carbon, coating silicon-containing particles with inorganic or polymeric materials, and replacing standard binder materials. Much work has been devoted to suppressing dendrite formation in LMBs by forming stable coating layers on the surface of lithium metal, preparing composite anodes and alloys, and changing the composition of electrolytes. At the same time, in the field of electrolyte development, many research works have been devoted to the search for new hybrid polymer electrolytes containing lithium-conducting inorganic materials.     

Non-solvating fluorosulfonyl carboxylate enables temperature-tolerant lithium metal batteries

Advanced electrolyte engineering is an important strategy for developing high-efficacy lithium(Li) metal batteries(LMBs). Unfortunately, the current electrolytes limit the scope for creating batteries that perform well over temperature ranges. Here, we present a new electrolyte design that uses fluorosulfonyl carboxylate as a non-solvating solvent to form difluoroxalate borate(DFOB-) anion-rich solvation sheath,to realize high-performance working of temperature-tolerant LMBs. With this optimized...     

A solvent-based intelligence ink for oxygen

A solvent-based, irreversible oxygen indicator ink is described, comprising semiconductor photocatalyst nanoparticles, a solvent-soluble redox dye, mild reducing agent and polymer. Based on such an ink, a film -- made of titanium dioxide, a blue, solvent-soluble, coloured ion-paired methylene blue dye, glycerol and the polymer zein -- loses its colour rapidly (<30 s) upon exposure to UVA light and remains colourless in an oxygen-free atmosphere, returning to its original blue colour upon exposure to air. In the latter step the rate of colour recovery is proportional to the level of ambient oxygen and the same film can be UV-activated repeatedly. The mechanism of this novel, UV-activated, solvent-based, colorimetric oxygen indicator is discussed, along with its possible applications.     

Inhibition of lithium dendrites and dead lithium by an ionic liquid additive toward safe and stable lithium metal anodes

The uncontrolled growth of lithium dendrites and accumulation of “dead lithium” upon cycling are among the main obstacles that hinder the widespread application of lithium metal anodes. Herein, an ionic liquid (IL) consisting of 1-methyl-1-propylpiperidinium cation (Pp₁₃⁺) and bis(fluorosulfonyl)imide anion (FSI^?), was chosen as the additive in propylene carbonate (PC)-based liquid electrolytes to circumvent the shortcoming of lithium metal anodes. The optimal 1% Pp₁₃FSI acts as the role of electrostatic shielding, lithiophobic effect and participating in the formation of solid electrolyte interface (SEI) layer with enhanced properties. The in-situ optical microscopy records that the addition of IL can effectively inhibit the growth of lithium dendrites and the corrosion of lithium anode. This study delivers an effective modification to optimize electrolytes for stable lithium metal batteries.     

A hydrophobic artificial solid-interphase-protective layer with fast self-healable capability for stable lithium metal anodes

Science China Chemistry - Lithium (Li) metal has been considered as one of the most promising anodes for high-energy-density batteries. However, the hyperactivity of metallic Li and its dendrite...     

A robust interface enabled by electrospun membrane with optimal resistance in lithium metal batteries

A uniform diffusion layer is essential for non-dendritic deposition of lithium in high-density lithium batteries.However,natural pristine solid electrolyte interface(SEI)is always porous and inhomogeneous because of repeated breakdown and repair cycles,whereas ideal materials with excellent mechanical property for artificial SEIs remain a challenge.Herein,a robust and stable interface is achieved by spinning soft polymer associated with few MoO₃ into fibers,and thus mechanical property of fibers other than materials determines mechanical performance of the interface which can be optimized by adjusting parameters.Furthermore,lithium deposited underneath the layer is enabled by constructing an optimal resistance to make the membrane serve as an artificial SEI rather than lithium host.As a result,dendritefree lithium was observed underneath the membrane,and stable interface for long-term cycling was also indicated by EIS measurements.The lithium iron phosphate(LiFePO₄)full-cell with coated electrode demonstrated an initial capacity of 155.2 m Ah g^-1,and 80%of its original capacity was retained after 500 cycles at 2.0℃ without any additive in carbonate-based electrolyte.     

Loss of metallicity in metal rich lithium oxide clusters

Mixed lithium-lithium oxide aggregates are experimentally obtained from unimolecular evaporative cascades starting at metal rich Li _p ⁺ (Li₂O)_n species and ending with the stoichiometric limit Li⁺(Li₂O)_n, for several sizes of the oxide part (Li₂O)_n with 0 ≤ n ≤ 8. The results show evidence of the vanishing of the properties of the quantum metallic droplet i.e. shell closing and odd-even alternation, portrayed in the dissociation energy, with increasing size of the oxide component. The competition between monomer and dimer lithium evaporation from the heated metal rich Li _p ⁺ (Li₂O)_n species points out the influence of the perturbation induced by the oxide component on the mixed metal oxide clusters.     

Recent progress in liquid electrolytes for lithium metal batteries

Li metal batteries are revived as the next-generation batteries beyond Li-ion batteries. The Li metal anode can be paired with intercalation-type cathodes LiMO₂ and conversion-type cathodes such as sulfur and oxygen. Then, energy densities of Li/LiMO₂ and Li/S,O₂ batteries can reach 400 Whkg^?1 and more than 500 Whkg^?1, respectively, which surpass that of the state-of-the-art LIB (280 Whkg^?1). However, replacing the intercalation-type graphite anode with the Li metal anode suffers from low coulombic efficiency during repeated Li plating/stripping processes, which leads to short cycle lifetime and potential safety problems. The key solution is to construct a stable and uniform solid electrolyte interphase with high Li⁺ transport and high elastic strength on the Li metal anode. This review summarizes recent progress in improving the solid electrolyte interphase by tailoring liquid electrolytes, a classical but the most convenient and cost-effective strategy.