Tailoring Practically Accessible Polymer/Inorganic Composite Electrolytes for All-Solid-State Lithium Metal Batteries:A Review

Solid-state electrolytes(SSEs)are widely considered the essential components for upcoming rechargeable lithium-ion batteries owing to the potential for great safety and energy density.Among them,polymer solid-state electrolytes(PSEs)are competitive candidates for replacing commercial liquid electrolytes due to their flexibility,shape versatility and easy machinability.Despite the rapid development of PSEs,their practical application still faces obstacles including poor ionic conductivity,narrow electrochemical stable window and inferior mechanical strength.Polymer/inorganic composite electrolytes(PIEs)formed by adding ceramic fillers in PSEs merge the benefits of PSEs and inorganic solid-state electrolytes(ISEs),exhibiting appreciable comprehensive properties due to the abundant interfaces with unique characteristics.Some PIEs are highly compatible with high-voltage cathode and lithium metal anode,which offer desirable access to obtaining lithium metal batteries with high energy density.This review elucidates the current issues and recent advances in PIEs.The performance of PIEs was remarkably influenced by the characteristics of the fillers including type,content,morphology,arrangement and surface groups.We focus on the molecular interaction between different components in the composite environment for designing high-performance PIEs.Finally,the obstacles and opportunities for creating high-performance PIEs are outlined.This review aims to provide some theoretical guidance and direction for the development of PIEs.

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.

All-solid-state lithium batteries with inorganic solid electrolytes:Review of fundamental science

The scientific basis of all-solid-state lithium batteries with inorganic solid electrolytes is reviewed briefly, touching upon solid electrolytes, electrode materials, electrolyte/electrode interface phenomena, fabrication, and evaluation. The challenges and prospects are outlined as well.

A critical review on composite solid electrolytes for lithium batteries:Design strategies and interface engineering

The rapid development of new energy vehicles and 5G communication technologies has led to higher demands for the safety,energy density,and cycle performance of lithium-ion batteries as power sources.However,the currently used liquid carbonate compounds in commercial lithium-ion battery electrolytes pose potential safety hazards such as leakage,swelling,corrosion,and flammability.Solid electrolytes can be used to mitigate these risks and create a safer lithium battery.Furthermore,high-energy density can be achieved by using solid electrolytes along with high-voltage cathode and metal lithium anode.Two types of solid electrolytes are generally used:inorganic solid electrolytes and polymer solid electrolytes.Inorganic solid electrolytes have high ionic conductivity,electrochemical stability window,and mechanical strength,but suffer from large solid/solid contact resistance between the electrode and electrolyte.Polymer solid electrolytes have good flexibility,processability,and contact interface properties,but low room temperature ionic conductivity,necessitating operation at elevated temperatures.Composite solid electrolytes(CSEs) are a promising alternative because they offer light weight and flexibility,like polymers,as well as the strength and stability of inorganic electrolytes.This paper presents a comprehensive review of recent advances in CSEs to help researchers optimize CSE composition and interactions for practical applications.It covers the development history of solid-state electrolytes,CSE properties with respect to nanofillers,morphology,and polymer types,and also discusses the lithium-ion transport mechanism of the composite electrolyte,and the methods of engineering interfaces with the positive and negative electrodes.Overall,the paper aims to provide an outlook on the potential applications of CSEs in solid-state lithium batteries,and to inspire further research aimed at the development of more systematic optimization strategies for CSEs.

Solid-State Electrolytes for Lithium-Sulfur Batteries

Secondary lithium-sulfur batteries have attracted extensive attention due to their high energy density,low cost and environment friendly.However,the"shuttle effect"of polysulfides dissolved in liquid electrolytes leads to a decrease of the cell Coulomb efficiency(CE).Therefore,researchers have used solid electrolytes instead of traditional liquid electrolytes and separators to suppress the"shuttle effect"of polysulfides and the growth of lithium dendrites.The progress in electrolytes for solid-state lithium-sulfur batteries including solid-state polymer,inorganic,and composite electrolytes to solve the issues is summarized.

Ameliorating the interfacial issues of all-solid-state lithium metal batteries by constructing polymer/inorganic composite electrolyte

Lithium metal is one of the most promising anodes for next-generation batteries due to its high capacity and low reduction potential.However,the notorious Li dendrites can cause the short life span and safety issues,hindering the extensive application of lithium batteries.Herein,Li_(7)La_(3)Zr_(2)O_(12)(LLZO)ceramics are integrated into polyethylene oxide(PEO)to construct a facile polymer/inorganic composite solid-state electrolyte(CSSE)to inhibit the growth of Li dendrites and widen the electrochemical stability window.Given the feasibility of our strategy,the designed PEO-LLZO-LiTFSI composite solid-state electrolyte(PLLCSSE)exhibits an outstanding cycling property of 134.2 mAh g^(-1) after 500 cycles and the Coulombic efficiency of 99.1%after 1000 cycles at 1 C in LiFePO_(4)-Li cell.When cooperated with LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)cathode,the PLL-CSSE renders a capacity retention of 82.4%after 200 cycles at 0.2 C.More importantly,the uniform dispersion of LLZO in PEO matrix is tentative tested via Raman and FT-IR spectra and should be responsible for the improved electrochemical performance.The same conclusion can be drawn from the interface investigation after cycling.This work presents an intriguing solid-state electrolyte with high electrochemical performance,which will boost the development of all-solid-state lithium batteries with high energy density.

Review of the electrochemical performance and interfacial issues of high-nickel layered cathodes in inorganic all-solid-state batteries

All-solid-state batteries potentially exhibit high specific energy and high safety,which is one of the development directions for nextgeneration lithium-ion batteries.The compatibility of all-solid composite electrodes with high-nickel layered cathodes and inorganic solid electrolytes is one of the important problems to be solved.In addition,the interface and mechanical problems of high-nickel layered cathodes and inorganic solid electrolyte composite electrodes have not been thoroughly addressed.In this paper,the possible interface and mechanical problems in the preparation of high-nickel layered cathodes and inorganic solid electrolytes and their interface reaction during charge–discharge and cycling are reviewed.The mechanical contact problems from phenomena to internal causes are also analyzed.Uniform contact between the high-nickel cathode and solid electrolyte in space and the ionic conductivity of the solid electrolyte are the prerequisites for the good performance of a high-nickel layered cathode.The interface reaction and contact loss between the high-nickel layered cathode and solid electrolyte in the composite electrode directly affect the passage of ions and electrons into the active material.The buffer layer constructed on the high-nickel cathode surface can prevent direct contact between the active material and electrolyte and slow down their interface reaction.An appropriate protective layer can also slow down the interface contact loss by reducing the volume change of the high-nickel layered cathode during charge and discharge.Finally,the following recommendations are put forward to realize the development vision of high-nickel layered cathodes:(1)develop electrochemical systems for high-nickel layered cathodes and inorganic solid electrolytes;(2)elucidate the basic science of interface and electrode processes between high-nickel layered cathodes and inorganic solid electrolytes,clarify the mechanisms of the interfacial chemical and electrochemical reactions between the two materials,and address the intrinsic safety issues;(3)strengthen the development of research and engineering technologies and their preparation methods for composite electrodes with high-nickel layered cathodes and solid electrolytes and promote the industrialization of all-solid-state batteries.

All-inorganic nitrate electrolyte for high-performance lithium oxygen battery

Lithium-oxygen(Li-O_(2))batteries have been regarded as an expectant successor for next-generation energy storage systems owing to their ultra-high theoretical energy density.However,the comprehensive properties of the commonly utilized organic salt electrolyte are still unsatisfactory,not to mention their expensive prices,which seriously hinders the practical production and application of Li-O_(2) batteries.Herein,we have proposed a low-cost all-inorganic nitrate electrolyte(LiNO_(3)-KNO_(3)-DMSO)for Li-O_(2) batteries.The inorganic nitrate electrolyte exhibits higher ionic conductivity and a wider electrochemical stability window than the organic salt electrolyte.The existence of K+can stabilize the O_(2)-intermediate,promoting the discharge process through the solution pathway with an enlarged capacity.Even at an ultra-low concentration of 0.01 M,the K+can still remain stable to promote the solution discharge process and also possess a new function of inhibiting the dendrite growth by electrostatic shielding,further enhancing the battery stability and contributing to the long cycle lifetime.As a result,in the 0.99 M LiNO_(3)-0.01 M KNO_(3)-DMSO electrolyte,the Li-O_(2) batteries exhibit prolonged cycling performance(108 cycles)and excellent rate performance(2 A·g^(-1)),significantly superior to the organic salt one.

Safe and Stable Lithium Metal Batteries Enabled by an Amide-Based Electrolyte

The formation of lithium dendrites and the safety hazards arising from flammable liquid electrolytes have seriously hindered the development of high-energy-density lithium metal batteries.Herein,an emerging amide-based electrolyte is proposed,containing LiTFSI and butyrolactam in different molar ratios.1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropylether and fluoroethylene carbonate are introduced into the amide-based electrolyte as counter solvent and additives.The well-designed amide-based electrolyte possesses nonflammability,high ionic conductivity,high thermal stability and electrochemical stability(>4.7 V).Besides,an inorganic/organic-rich solid electrolyte interphase with an abundance of LiF,Li3N and Li-N-C is in situ formed,leading to spherical lithium deposition.The formation mechanism and solvation chemistry of amide-based electrolyte are further inves-tigated by molecular dynamics simulations and density functional theory.When applied in Li metal batteries with LiFePO4 and LiMn2O4 cathode,the amide-based electrolyte can enable stable cycling performance at room temperature and 60℃.This study provides a new insight into the development of amide-based electrolytes for lithium metal batteries.

Thermal Behavior and Lithium Ion Conductivity of L_2O-Al_2O_3-TiO_2-SiO_2-P_2O_5 Glass-ceramics

A lithium ion conductive solid electrolyte, L20-AI203-TiO2-SiO2-P20s glass with NASICON- type structure have been synthesized and transformed into glass-ceramic through thermal-treatment at various temperatures from 700 to 1 000 ~C for 12 h. The differential scanning calorimetry （DSC）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and complex impedance techniques were employed to characterize the samples. The experimental results indicated that the capability of glass forming in this system is superior to that of L20-A1203-TiO2-PzO~. The glass has an amorphous structure and resultant glass-ceramic mainly consisting of LiTi2（PO4）3 phases. Impurity phases AIPO4, TiO2, TiP207 and unidentified phase were observed. With the enhanced heat-treatment temperature, grain grew gradually and lithium ion conductivity of glass-ceramics increased accordingly, the related impedance semicircles were depressed gradually and even disappeared, which could be analytically explained by the coordinate action of the ＇Constant phase element＇ （CPE） model and the ＇Concept of Mismatch and Relaxation＇ model （CMR）. When the sample is devitrified at 1 000 ~C, the maximum room temperature lithium ion conductivity comes up to 4.1 x 10-4 S/cm, which is suitable for the application as an electrolyte of all-solid-state lithium batteries.

Solid-state electrolytes for safe rechargeable lithium metal batteries:a strategic view

Despite the efforts devoted to the identification of new electrode materials with higher specific capacities and electrolyte additives to mitigate the well-known limitations of current lithium-ion batteries,this technology is believed to have almost reached its energy density limit.It suffers also of a severe safety concern ascribed to the use of flammable liquid-based electrolytes.In this regard,solid-state electrolytes(SSEs)enabling the use of lithium metal as anode in the so-called solid-state lithium metal batteries(SSLMBs)are considered as the most desirable solution to tackle the aforementioned limitations.This emerging technology has rapidly evolved in recent years thanks to the striking advances gained in the domain of electrolyte materials,where SSEs can be classified according to their core chemistry as organic,inorganic,and hybrid/composite electrolytes.This strategic review presents a critical analysis of the design strategies reported in the field of SSEs,summarizing their main advantages and disadvantages,and providing a future perspective toward the rapid development of SSLMB technology.

A review of solid electrolytes for safe lithium-sulfur batteries

Due to the high specific capacity, low cost, and environmental friendliness, lithium-sulfur batteries hold great potential to become the mainsiay of next-generation energy storage system. Regarding the composition of sulfur/carbon in cathode, flammable organic liquid electrolyte, and lithium metal anode, great concerns about the safety have been raised. Hence solid-electrolyte-based lithium-sulfur batteries, as one alternative route for safe batteries, are highly interested. This review highlights the recent research progress of lithium-sulfur batteries with solid electrolytes. Both sulfide solid electrolytes and oxide solid electrolytes are included. The sulfide solid electrolytes are mainly employed in all-solid-state lithium-sulfur batteries, while the oxide solid electrolytes are applied in hybrid electrolyte for lithium-sulfur batteries. The challenges and perspectives in this field are also featured on the basis of its current progress.

Li-rich channels as the material gene for facile lithium diffusion in halide solid electrolytes

Halide solid electrolytes have attracted intense research interest recently for application in all-solid-state lithiumion batteries. Herein, we present a systematic first-principles study of the Li3MX6 (M: multivalent cation;X:halogen anion) halide family that unveils the link between Li-rich channels and ionic conductivity, highlightingthe former as a material gene in these compounds. By screening a total of 180 halides for those with highthermodynamic stability, wide electrochemical window, low chemical reactivity, and decent Li-ion conductivity,we identify seven unexplored candidates for solid electrolytes. From these halides and another four prototypecompounds, we discover that the facile Li diffusion is rooted in the availability of diffusion pathways which canavoid direct connection with M cations-that is, where the local environment is Li-rich. These findings shed lighton strategies for regulating cation and anion frameworks to establish Li-rich channels in the design of high-performance inorganic solid electrolytes.

Revealing milling durations and sintering temperatures on conductivity and battery performances of Li_(2.25)Zr_(0.75)Fe_(0.25)Cl_(6)electrolyte

Halide electrolytes in solid-state batteries with excellent oxidative stability and high ionic conductivity have been well reported recently.However,the high-cost rare-earth elements and long duration of highrotation milling procure are the major obstacles.Herein,we have successfully synthesized the low cost Li_(2.25)Zr_(0.75)Fe_(0.25)Cl_(6)electrolyte consisting of abundant elements with comparable Li-ion conductivity in a short milling duration of 4 h.Phase transition of the annealed sample was also carefully investigated.Li Ni_(0.6)Co_(0.2)Mn_(0.2)O_(2)/Li_(2.25)Zr_(0.75)Fe_(0.25)Cl_(6)/Li_(5.5)PS_(4.5)Cl_(1.5)/In-Li batteries using different halide electrolytes were constructed and cycled at different voltage windows.Solid-state battery using Li_(2.25)Zr_(0.75)Fe_(0.25)Cl_(6)electrolyte obtained from long milling duration delivers higher discharge capacities and superior capacity retention than shorter milling time between 3.0 and 4.3 V.It delivers much higher discharge capacity when cycled at elevated temperature(60℃)and suffers fast capacity degradation when the upper cut-off voltage increases to 4.5 V at the same current density.This work provides an efficiency synthesis strategy for halide solid electrolyte and studies its applications in all-solid-state batteries in a wide temperature range.