Dual-Functional Electrode Promoting Dendrite-Free and CO_(2) Utilization Enabled High-Reversible Symmetric Na-CO_(2) Batteries

Sodium-carbon dioxide(Na-CO_(2))batteries are regarded as promising energy storage technologies because of their impressive theoretical energy density and CO_(2)reutilization,but their practical applications are restricted by uncontrollable sodium dendrite growth and poor electrochemical kinetics of CO_(2)cathode.Constructing suitable multifunctional electrodes for dendritefree anodes and kinetics-enhanced CO_(2)cathodes is considered one of the most important ways to advance the practical application of Na-CO_(2)batteries.Herein,RuO2 nanoparticles encapsulated in carbon paper(RuCP)are rationally designed and employed as both Na anode host and CO_(2)cathode in Na-CO_(2)batteries.The outstanding sodiophilicity and high catalytic activity of RuCP electrodes can simultaneously contribute to homogenous Na+distribution and dendrite-free sodium structure at the anode,as well as strengthen discharge and charge kinetics at the cathode.The morphological evolution confirmed the uniform deposition of Na on RuCP anode with dense and flat interfaces,delivering enhanced Coulombic efficiency of 99.5%and cycling stability near 1500 cycles.Meanwhile,Na-CO_(2)batteries with RuCP cathode demonstrated excellent cycling stability(>350 cycles).Significantly,implementation of a dendrite-free RuCP@Na anode and catalytic-site-rich RuCP cathode allowed for the construction of a symmetric Na-CO_(2)battery with long-duration cyclability,offering inspiration for extensive practical uses of Na-CO_(2)batteries.

Enabling High-Performance Sodium Battery Anodes by Complete Reduction of Graphene Oxide and Cooperative In-Situ Crystallization of Ultrafine SnO_(2)Nanocrystals

The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.

Seamless Stitching of Redox Windows to Enable High-Voltage Resilient Solid Sodium Ion Batteries

While sulfide solid electrolytes such as Na_(11)Sn_(2)PS_(12)can allow fast transport of Na+ions,their utilization in solid sodium ion batteries is rather unsuccessful since they are not electrochemically compatible to both high-voltage cathodes and sodium metal anode.In this work,we devise an effective approach toward realizing solid sodium ion batteries,using the Na_(11)Sn_(2)PS_(12)electrolyte and slurry-coated NASICON-type Na_(3)MnTi(PO_(4))_(3)@C as high-voltage cathode,highly beneficial for low processing cost and high content/loading of active cathode matter.We report that through significantly improved integrity of electrolyte-cathode interface,such solid sodium ion batteries can deliver outstanding cycling and rate performance,with a charge voltage resilience up to 4.1 V,a high cathode discharge capacity of 128.7 mAh g^(-1)against the Na_(3)MnTi(PO_(4))_(3)@C in cathode is achieved at 0.05 C,and capacity retention ratio of 82%with a rate of 0.1 C is realized after prolonged cycling at room temperature.Besides,we demonstrate that such a solid sodium ion battery can even perform at a sub-zero Celsius temperature of-10℃,when the conventional control cell using liquid electrolyte completely fail to function.This work is to offer a dependable avenue in engineering next generation of safe solid ion batteries based on highly sustainable and much cheaper material resources.

Enabling Argyrodite Sulfides as Superb Solid-State Electrolyte with Remarkable Interfacial Stability Against Electrodes

While argyrodite sulfides are getting more and more attention as highly promising solid-state electrolytes(SSEs)for solid batteries,they also suffer from the typical sulfide setbacks such as poor electrochemical compatibility with Li anode and high-voltage cathodes and serious sensitivity to humid air,which hinders their practical applications.Herein,we have devised an effective strategy to overcome these challenging shortcomings through modification of chalcogen chemistry under the guidance of theoretical modeling.The resultant Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)delivered excellent electrochemical compatibility with both pure Li anode and high-voltage LiCoO_(2)cathode,without compromising the superb ionic conductivity of the pristine sulfide.Furthermore,the current SSE also exhibited highly improved stability to oxygen and humidity,with further advantage being more insulating to electrons.The remarkably enhanced compatibility with electrodes is attributed to in situ formation of helpful electrolyte–electrode interphases.The formation of in situ anode–electrolyte interphase(AEI)enabled stable Li plating/stripping in the Li|Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)|Li symmetric cells at a high current density up to 1 mA cm^(-2)over 200 h and 2 mA cm^(-2)for another 100 h.The in situ amorphous nano-film cathode–electrolyte interphase(CEI)facilitated protection of the SSE from decomposition at elevated voltage.Consequently,the synergistic effect of AEI and CEI helped the LiCoO_(2)|Li_(6.25)PS_(4)O_(1.25)Cl_(0.75)|Li full-battery cell to achieve markedly better cycling stability than that using the pristine Li_(6)PS_(5)Cl as SSE,at a high area loading of the active cathode material(4 mg cm^(-2))in type-2032 coin cells.This work is to add a desirable SSE in the argyrodite sulfide family,so that high-performance solid battery cells could be fabricated without the usual need of strict control of the ambient atmosphere.

Atomic Layer Coated Al_(2)O_(3) on Nitrogen Doped Vertical Graphene Nanosheets for High Performance Sodium Ion Batteries

Heteroatom doped graphene materials are considered as promising anode for high-performance sodium-ion batteries(SIBs).Defective and porous structure especially with large specific surface area is generally considered as a feasible strategy to boost reaction kinetics;however,the unwanted side reaction at the anode hinders the practical application of SIBs.In this work,a precisely controlled Al_(2)O_(3)coated nitrogen doped vertical graphene nanosheets(NVG)anode material has been proposed,which exhibits excellent sodium storage capacity and cycling stability.The ultrathin Al_(2)O_(3)coating on the NVG is considered to help construct an advantageous interface between electrode and electrolyte,both alleviating the electrolyte decomposition and enhancing sodium adsorption ability.As a result,the optimal Al_(2)O_(3)coated NVG materials delivers a high reversible capacity(835.0 mAh g^(-1))and superior cycling stability(retention of 92.3%after 5000 cycles).This work demonstrates a new way to design graphene-based anode materials for highperformance sodium-ion batteries.

Stable all-solid-state battery enabled with Li_(6.25)PS_(5.25)Cl_(0.75) as fast ion-conducting electrolyte

All-solid-state batteries(ASSB) with lithium anode have attracted ever-increasing attention towards developing safer batteries with high energy densities.While great advancement has been achieved in developing solid electrolytes(SE) with superb ionic conductivity rivalling that of the current liquid technology,it has yet been very difficult in their successful application to ASSBs with sustaining rate and cyclic performances.Here in this work,we have realized a stable ASSB using the Li_(6.25)PS_(5.25)Cl_(0.75) fast ionconducting electrolyte together with LiNbO_3 coated LiCoO_2 as cathode and lithium foil as the anode.The effective diffusion coefficient of Li-ions in the battery is higher than 10^(-12) cm~2 s^(-1),and the significantly enhanced electrochemical matching at the cathode-electrolyte interface was essential to enable long-term stability against high oxidation potential,with the LCO@LNO/Li_(6.25)PS_(5.25)Cl_(0.75)/Li battery to retain 74.12% capacity after 430 cycles at 100 μA cm-2 and 59.7% of capacity after 800 cycles at 50 μA cm^(-2),at a high charging cut-off voltage of 4.2 V.This demonstrates that the Li_(6.25)PS_(5.25)Cl_(0.75) can be an excellent electrolyte for the realization of stable ASSBs with high-voltage cathodes and metallic lithium as anode,once the electrochemical compatibility between cathode and electrolyte can be addressed with a suitable buffer coating.

Influence of Halide Choice on Formation of Low-Dimensional Perovskite Interlayer in Efficient Perovskite Solar Cells

Recent advances in heterojunction and interfacial engineering of perovskite solar cells(PSCs)have enabled great progress in developing highly efficient and stable devices.Nevertheless,the effect of halide choice on the formation mechanism,crystallography,and photoelectric properties of the lowdimensional phase still requires further detailed study.In this work,we present key insights into the significance of halide choice when designing passivation strategies comprising large organic spacer salts,clarifying the effect of anions on the formation of quasi-2D/3D heterojunctions.To demonstrate the importance of halide influences,we employ novel neo-pentylammonium halide salts with different halide anions(neoPAX,X=I,Br,or Cl).We find that regardless of halide selection,iodide-based(neoPA)_(2)(FA)_((n-1))PbnI_((3n+1))phases are formed above the perovskite substrate,while the added halide anions diffuse and passivate the perovskite bulk.In addition,we also find the halide choice has an influence on the degree of dimensionality(n).Comparing the three halides,we find that chloride-based salts exhibit superior crystallographic,enhanced carrier transport,and extraction compared to the iodide and bromide analogs.As a result,we report high power conversion efficiency in quasi-2D/3D PSCs,which are optimal when using chloride salts,reaching up to 23.35%,and improving long-term stability.

Significant performance enhancement of all-inorganic CsPbBr_(3)perovskite solar cells enabled by Nb-doped SnO_(2)as effective electron transport layer

All-inorganic CsPbBr_(3)-based perovskite solar cells(PSCs)have attracted great attention because of their high chemical and thermal stabilities in ambient air.However,the short-circuit current density(J_(sc))of CsPbBr_(3)-based PSCs is inadequate under solar illumination because of the wide bandgap,inefficient charge extraction and recombination loss,leading to lower power-conversion efficiencies(PCEs).It is envisaged that in addition to narrowing the bandgap by alloying,J_(sc)of the PSCs could be enhanced by effective improvement of electron transportation,suppression of charge recombination at the interface between the perovskite and electron transporting layer(ETL),and tuning of the space charge field in the device.In this work,Nb-doped SnO_(2)films as ETLs in the CsPbBr_(3)-based PSCs have been deposited at room temperature by high target utilization sputtering(Hi TUS).Through optimizing the Nb doping level alone,the J_(sc)was increased by nearly 19%,from 7.51 to 8.92 mA·cm^(-2)and the PCE was enhanced by 27%from 6.73%to 8.54%.The overall benefit by replacing the spin-coated SnO_(2)with sputtered SnO_(2)with Nb doping was up to 39%increase in J_(sc)and 62%increase in PCE.Moreover,the PCE of the optimized device showed negligible degradation over exposure to ambient environment(T~25°C,RH~45%),with 95.4%of the original PCE being maintained after storing the device for 1200 h.