Precise construction of RuPt dual single-atomic sites to optimize oxygen electrocatalytic behaviors for high-performance Zn-air batteries

The development of redox bifunctional electrocatalysts with high performance,low cost,and long lifetimes is essential for achieving clean energy goals.This study proposed an atom capture strategy for anchoring dual single atoms(DSAs)in a zinc-zeolitic imidazolate framework(Zn-ZIF),followed by calcination under an N_(2) atmosphere to synthesize ruthenium-platinum DSAs supported on a nitrogendoped carbon substrate(RuPt DSAs-NC).Theoretical calculations showed that the degree of Ru 5dxz-~*O 2p_x orbital hybridization was high when^(*)O was adsorbed at the Ru site,indicating enhanced covalent hybridization of metal sites and oxygen ligands,which benefited the adsorption of intermediate species.The presence of the RuPtN_6 active center optimized the absorption-desorption behavior of intermediates,improving the electrocatalytic performance of the oxygen reduction reaction(ORR)and the oxygen evolution reaction(DER),RuPt DSAs-NC exhibited a 0.87 V high half-wave potential and a 268 mV low overpotential at 10 mA cm^(-2)in an alkaline environment.Furthermore,rechargeable zinc-air batteries(ZABs)achieved a peak power density of 171 MW cm^(-2).The RuPt DSAs-NC demonstrated long-term cycling for up to 500 h with superior round-trip efficiency.This study provided an effective structural design strategy to construct DSAs active sites for enhanced electrocata lytic performance.

Aqueous Zinc Batteries with Ultra‑Fast Redox Kinetics and High Iodine Utilization Enabled by Iron Single Atom Catalysts

Rechargeable aqueous zinc iodine(ZnǀǀI_(2))batteries have been promising energy storage technologies due to low-cost position and constitutional safety of zinc anode,iodine cathode and aqueous electrolytes.Whereas,on one hand,the low-fraction utilization of electrochemically inert host causes severe shuttle of soluble polyiodides,deficient iodine utilization and sluggish reaction kinetics.On the other hand,the usage of high mass polar electrocatalysts occupies mass and volume of electrode materials and sacrifices device-level energy density.Here,we propose a“confinement-catalysis”host composed of Fe single atom catalyst embedding inside ordered mesoporous carbon host,which can effectively confine and catalytically convert I_(2)/I^(−)couple and polyiodide intermediates.Consequently,the cathode enables the high capacity of 188.2 mAh g^(−1)at 0.3 A g^(−1),excellent rate capability with a capacity of 139.6 mAh g^(−1)delivered at high current density of 15 A g^(−1)and ultra-long cyclic stability over 50,000 cycles with 80.5%initial capacity retained under high iodine loading of 76.72 wt%.Furthermore,the electrocatalytic host can also accelerate the I^(+)↔I_(2)conversion.The greatly improved electrochemical performance originates from the modulation of physicochemical confinement and the decrease of energy barrier for reversible I−/I_(2)and I_(2)/I^(+)couples,and polyiodide intermediates conversions.

Single‐atomic Co‐B_(2)N_(2)sites anchored on carbon nanotube arrays promote lithium polysulfide conversion in lithium-sulfur batteries

Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.

Enhancing thermodynamic stability of single-crystal Ni-rich cathode material via a synergistic dual-substitution strategy

Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance and safety performance or thermal stability)will restrain their wide commercial application.Herein,a single-crystal Ni-rich Li Ni_(0.83)Co_(0.12)Mn_(0.05)O_(2) cathode material is synthesized and modified by a dual-substitution strategy in which the high-valence doping element improves the structural stability by forming strong metal–oxygen binding forces,while the low-valence doping element eliminates high Li^(+)/Ni^(2+)mixing.As a result,this synergistic dual substitution can effectively suppress H2-H3 phase transition and generation of microcracks,thereby ultimately improving the thermodynamic stability of Ni-rich cathode material.Notably,the dual-doped Ni-rich cathode delivers an extremely high capacity retention of 81%after 250 cycles(vs.Li/Li+)in coin-type half cells and 87%after 1000 cycles(vs.graphite/Li^(+))in pouch-type full cells at a high temperature of 55℃.More impressively,the dual-doped sample exhibits excellent thermal stability,which demonstrates a higher thermal runaway temperature and a lower calorific value.The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures,which will significantly advance the high-energy-density and high-safety cathodes to the subsequent commercialization.

COF-based single Li^(+)solid electrolyte accelerates the ion diffusionandrestrains dendritegrowthin quasi-solid-state organic batteries

A solid-state electrolyte(SSE),which is a solid ionic conductor and electroninsulating material,is known to play a crucial role in adapting a lithium metal anode to a high-capacity cathode in a solid-state battery.Among the various SSEs,the single Li-ion conductor has advantages in terms of enhancing the ion conductivity,eliminating interfacial side reactions,and broadening the electrochemical window.Covalent organic frameworks(COFs)are optimal platforms for achieving single Li-ion conduction behavior because of wellordered one-dimensional channels and precise chemical modification features.Herein,we study in depth three types of Li-carboxylate COFs(denoted LiOOC-COFn,n=1,2,and 3)as single Li-ion conducting SSEs.Benefiting from well-ordered directional ion channels,the single Li-ion conductor LiOOC-COF3 shows an exceptional ion conductivity of 1.36×10^(-5) S cm^(-1) at room temperature and a high transference number of 0.91.Moreover,it shows excellent electrochemical performance with long-term cycling,high-capacity output,and no dendrites in the quasi-solid-state organic battery,with the organic small molecule cyclohexanehexone(C_(6)O_(6))as the cathode and the Li metal as the anode,and enables effectively avoiding dissolution of the organic electrode by the liquid electrolyte.

A Comparative Investigation of Single Crystal and Polycrystalline Ni-Rich NCMs as Cathodes for Lithium-Ion Batteries

Nickel-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(NCM,1-x-y≥0.6)is known as a promising cathode material for lithium-ion batteries since its superiority of high voltage and large capacity.However,polycrystalline Ni-rich NCMs suffer from poor cycle stability,limiting its further application.Herein,single crystal and polycrystalline LiNi_(0.84)Co_(0.07)Mn_(0.09)O_(2)cathode materials are compared to figure out the relation of the morphology and the electrochemical storage performance.According to the Li^(+)diffusion coefficient,the lower capacity of single crystal samples is mainly ascribed to the limited Li+diffusion in the large bulk.In situ XRD illustrates that the polycrystalline and single crystal NCMs show a virtually identical manner and magnitude in lattice contraction and expansion during cycling.Also,the electrochemically active surface area(ECSA)measurement is employed in lithium-ion battery study for the first time,and these two cathodes show huge discrepancy in the ECSA after the initial cycle.These results suggest that the single crystal sample exhibits reduced cracking,surface side reaction,and Ni/Li mixing but suffers the lower Li^(+)diffusion kinetics.This work offers a view of how the morphology of Ni-rich NCM effects the electrochemical performance,which is instructive for developing a promising strategy to achieve good rate performance and excellent cycling stability.

Mitigating kinetic hindrance of single-crystal Ni-rich cathodes through morphology modulation,nickel reduction,and lithium vacancy generation achieved by terbium doping

Single crystallization has proven to be effective in enhancing the capacity and stability of Ni-rich LiNi_(1-x-y)Co_(x)Mn_(y)O_(2)(SNCM)cathode materials,particularly at high cut-off voltages.Nevertheless,the synthesis of high-quality single-crystal particles remains challenging because of severe particle agglomeration and irregular morphologies.Moreover,the limited kinetics of solid-phase Li^(+)diffusion pose a significant concern because of the extended diffusion path in large single-crystal particles.To address these challenges,we developed a Tb-doped single-crystal LiNi_(0.83)Co_(0.11)Mn_(0.06)O_(2)(SNCM-Tb)cathode material using a straightforward mixed molten salt sintering process.The Tb-doped Ni-rich single crystals presented a quasi-spherical morphology,which is markedly different from those reported in previous studies.Tb^(4+)oping significantly enhanced the dynamic transport of Li^(+)ions in the layered oxide phase by reducing the Ni valence state and creating Li vacancies.A SNCM-Tb material with 1 at%Tb doping shows a Li^(+)diffusion coefficient up to more than 9 times higher than pristine SNCM in the non-diluted state.In situ X-ray diffraction analysis demonstrated a significantly facilitated H1-H2-H3 phase transition in the SNCM-Tb materials,thereby enhancing their rate capacity and structural stability.SNCM-Tb exhibited a reversible capacity of 186.9 mA h g^(-1)at 5 C,retaining 94.6%capacity after 100 cycles at 0.5 C under a 4,5 V cut-off.Our study elucidates the Tb^(4+)doping mechanisms and proposes a scalable method for enhancing the performance of single-crystal Ni-rich NCM materials.

Working Condition Real-Time Monitoring Model of Lithium Ion Batteries Based on Distributed Parameter System and Single Particle Model

Lithium ion batteries are complicated distributed parameter systems that can be described preferably by partial differential equations and a field theory. To reduce the solution difficulty and the calculation amount, if a distributed parameter system is described by ordinary differential equations （ODE） during the analysis and the design of distributed parameter system, the reliability of the system description will be reduced, and the systemic errors will be introduced. Studies on working condition real-time monitoring can improve the security because the rechargeable LIBs are widely used in many electronic systems and electromechanical equipment. Single particle model （SPM） is the simplification of LIB under some approximations, and can estimate the working parameters of a LIB at the faster simulation speed. A LIB modelling algorithm based on PDEs and SPM is proposed to monitor the working condition of LIBs in real time. Although the lithium ion concentration is an unmeasurable distributed parameter in the anode of LIB, the working condition monitoring model can track the real time lithium ion concentration in the anode of LIB, and calculate the residual which is the difference between the ideal data and the measured data. A fault alarm can be triggered when the residual is beyond the preset threshold. A simulation example verifies that the effectiveness and the accuracy of the working condition real-time monitoring model of LIB based on PDEs and SPM.

Nickel single atom overcoordinated active sites to accelerate the electrochemical reaction kinetics for Li-S cathode

Lithium-sulfur(Li-S)batteries with high theoretical energy density are promising advanced energy storage devices.However,shuttling of dissolute lithium polysulfide(LiPSs)and sluggish conversion kinetics impede their applications.Herein,single nickel(Ni)atoms on two-dimensional(2D)nitrogen(N)-doped carbon with Ni-N_(4)-O overcoordinated structure(SANi-N_(4)-O/NC)are prepared and firstly used as a sulfur host of Li-S batteries.Due to the efficient polysulfides traps and highly LiPSs conversion effect of SANi-N_(4)-O/NC,the electrochemical performance of Li-S batteries obviously improved.The batteries can well operate even under high sulfur loading(5.8 mg cm^(-2))and lean electrolyte(6.1μL mg^(-1))condition.Meanwhile,density functional theory(DFT)calculations demonstrate that Ni single atom’s active sites decrease the energy barriers of conversion reactions from Li_(2)S_(8)to Li2S due to the strong interaction between SANi-N_(4)-O/NC and LiPSs.Thus,the kinetic conversion of LiPSs was accelerated and the shuttle effect is suppressed on SANi-N_(4)-O/NC host.This study provides a new design strategy for a 2D structure with single-atom overcoordinated active sites to facilitate the fast kinetic conversion of LiPSs for Li-S cathode.

Electrochemical Kinetic Modulators in Lithium–Sulfur Batteries:From Defect-Rich Catalysts to Single Atomic Catalysts

Lithium–sulfur batteries exhibit unparalleled merits in theoretical energy density(2600 W h kg^(-1))among next-generation storage systems.However,the sluggish electrochemical kinetics of sulfur reduction reactions,sulfide oxidation reactions in the sulfur cathode,and the lithium dendrite growth resulted from uncontrollable lithium behaviors in lithium anode have inhibited high-rate conversions and uniform deposition to achieve high performances.Thanks to the“adsorption-catalysis”synergetic effects,the reaction kinetics of sulfur reduction reactions/sulfide oxidation reactions composed of the delithiation of Li_(2)S and the interconversions of sulfur species are propelled by lowering the delithiation/diffusion energy barriers,inhibiting polysulfide shuttling.Meanwhile,the anodic plating kinetic behaviors modulated by the catalysts tend to uniformize without dendrite growth.In this review,the various active catalysts in modulating lithium behaviors are summarized,especially for the defect-rich catalysts and single atomic catalysts.The working mechanisms of these highly active catalysts revealed from theoretical simulation to in situ/operando characterizations are also highlighted.Furthermore,the opportunities of future higher performance enhancement to realize practical applications of lithium–sulfur batteries are prospected,shedding light on the future practical development.

Single-Atom Lithiophilic Sites Confined within Ordered Porous Carbon for Ultrastable Lithium Metal Anodes

Attributing to the high specific capacity and low electrochemical reduction potential,lithium(Li)metal is regarded as the most promising anode for high-energy Li batteries.However,the growth of lithium dendrites and huge volume change seriously limit the development of lithium metal batteries.To overcome these challenges,an ordered mesoporous N-doped carbon with lithiophilic single atoms is proposed to induce uniform nucleation and deposition of Li metal.Benefiting from the synergistic effects of interconnected three-dimensional ordered mesoporous structures and abundant lithiophilic single-atom sites,regulated local current density and rapid mass transfer can be achieved,leading to the uniform Li deposition with inhibition of dendrites and buffered volume expansion.As a result,the as-fabricated anode exhibits a high CE of 99.8%for 200 cycles.A stable voltage hysteresis of 14 mV at 5 mA cm^(−2)could be maintained for more than 1330 h in the symmetric cell.Furthermore,the full cell coupled with commercial LiFePO_(4)exhibits high reversible capacity of 108 mAh g^(−1)and average Coulombic efficiency of 99.8%from 5th to 350th cycles at 1 C.The ordered mesoporous carbon host with abundant lithiophilic single-atom sites delivers new inspirations into rational design of high-performance Li metal anodes.

Syntheses,challenges and modifications of single-crystal cathodes for lithium-ion battery

Single-crystal cathodes(SCCs)are promising substitute materials for polycrystal cathodes(PCCs)in lithium-ion batteries(LIBs),because of their unique ordered structure,excellent cycling stability and high safety performance.Cathode materials with layered(LiCoO_(2),LiNi_xCo_yMnzO_(2),LiNi_xCo_yAl_(2)O_(2))and spinel structure(LiMn_(2)O_(4),LiNi_(0.5)Mn_(1.5)O_(4))show a relatively stable electrochemical performance,but still lack of sufficient attention in research field.In this review,we begin with the definition,structural features and electrochemical advantages of SCCs.Common SCCs synthesis methods and the thermodynamic growth mechanism of SCCs with oriented facet exposure are summarized in the following part.Then we introduce the problems and challenges of SCCs faced and the corresponding modification strategies.Finally,the industrialization progress of SCCs is brifly outlined.We intend to tease out the difficulties and advances of SCCs to provide insights for future development of high-performance SCCs for practical LIBs.

Isolated Co single atoms in nitrogen-doped graphene for aluminum-sulfur batteries with enhanced kinetic response

Al-S batteries are promising next generation energy storage devices due to their high theoretical energy density(1340 Wh kg^(-1)),low cost,and safe operation.However,the electrochemical performance of Al-S batteries suffers poor reversibility owing to slow kinetic processes determined by the difficulty of reversible conversion between Al and S.Here,we proposed a single-atom catalysts comprising Co atoms embedded in a nitrogen-doped graphene(Co NG)as an electrochemical catalyst in the sulfur cathode that renders a reduced discharge-charge voltage hysteresis and improved sulfur utilization in the cathode.The structural and electrochemical analyses suggest that the Co NG facilitated both the formation and oxidation of Al S;during the electrochemical reactions of the sulfur species.Consequently,the Co NG-S composite can deliver a considerably reduced voltage hysteresis of 0.76 V and a reversible specific capacity of 1631 m Ah g^(-1) at 0.2 A g^(-1) with a sulfur utilization of more than 97%.

3D star-like atypical hybrid MOF derived single-atom catalyst boosts oxygen reduction catalysis

Developing high-efficiency,stable and non-precious electrocatalysts for oxygen reduction reaction(ORR)is highly important for energy conversion and storage.Single atom catalysts(SACs)show good potential in enhancing ORR,however,the specifical control over the coordination surroundings around single metal center to intrinsically modify the electron structure is still a great challenge.Herein,we demonstrate that a 3 D hybrid MOF composed of cobalt doped ZIF-L and ZIF-8,featuring star morphology with six equal branches,can be used as an advanced precursor for making the Co SACs for greatly boosted ORR.The as-synthesized Co_(SA)-N-C exhibits excellent ORR activity with E_(1/2) of 0.891 V in alkaline medium,outperforming the commercial Pt/C by 39 m V.Moreover,the E_(1/2) of Co_(SA)-N-C(0.790 V)is merely 15 m V,less than that of Pt/C(0.805 V)in acid medium,which is among the best in the reported state-of-the-art SACs.DFT calculations demonstrate that the enhanced ORR performance is assigned to the formation of atomically isolated cobalt atom coordinated three N atoms and one C atom,which is easier to decrease the free energy of rate determining step and accelerate the ORR process than that of traditional cobalt atom coordinated four N atoms.In addition,a primary Zn-air battery with Co_(SA)-N-C cathode reveals a maximum power density of 92.2 m W cm^(-2) at 120.0 m A cm^(-2),far higher than that of commercial catalysts(74.2 m W cm^(-2) at 110.0 m A cm^(-2)).

Carbon dots-derived carbon nanoflowers decorated with cobalt single atoms and nanoparticles as efficient electrocatalysts for oxygen reduction

The sluggish kinetics of oxygen reduction reaction(ORR)hinders the commercialization of Zn‐air batteries(ZABs).Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen‐containing intermediates during the 4e–ORR offers a practical route toward improving ORR kinetics.Herein,we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots‐derived carbon nanoflowers(Co SAs/NPs CNF).Co SAs/NPs CNF possessed a very high ORR activity(E_(1/2) of the Co SAs/NPs CNF catalyst is 0.83 V(vs.RHE)),and outstanding catalytic performance and stability when used as the air‐electrode catalyst in rechargeable ZABs(152.32 mW cm^(-2),1000.58 mWh gZn^(–1),and over 1300 cycles at a current density of 5 mA cm^(-2)).The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR.Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co‐N_(4) sites,significantly lowering the energy barriers for the rate‐determining step in ORR(adsorption of*OOH)and thereby delivering outstanding ORR performance.This work reveals that the combination of supported single‐atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis,outperforming catalysts containing only Co SAs or Co NPs.

Grain size regulation for balancing cycle performance and rate capability of LiNi_(0.9)Co_(0.055)Mn_(0.045)O_(2) single crystal nickel-rich cathode materials

It is challenging to balance the cyclability and rate capability of single crystal nickel-rich cathode materials(Ni>0.8).Multicomponent oxides by spray pyrolysis shows potential as highly-reactive precursors to synthesize single crystal nickel-rich cathode at lower temperature,yet Ni^(2+)will severely inhibit particle growth when Ni content exceeds 0.9.Herein,lithium nitrate(LiNO_(3))with low melting point and strong oxidation is introduced as collaborate lithium salts for fabrication of well-dispersed submicron and micron single crystal LiNi_(0.9)Co_(0.055)Mn_(0.045)O_(2)(NCM90)cathode without extra unit operation.By changing amount of LiNO_(3),particle size regulation is realized and cation disorder can be diminished.The as-prepared material with optimal content of 4 wt%LiNO_(3)(NCM90-4 LN)displays the most appropriate particle size(1μm)with approximately stoichiometric structure,and presents better kinetics characterization of lithium-ion diffusion(15%higher than NCM90)and good electrochemical performance with specific discharge capacity of 220.6 and 173.8 mAh g^(-1) at 0.1 C and 10 C at room temperature,respectively.This work broadens the conventional research methodology of size regulation for single crystal Ni-rich cathode materials and is indispensable for the development of designing principal of nickel-rich cathode materials for lithium-ion batteries.

单晶高镍三元正极材料的制备及改性研究进展

介绍了单晶高镍三元正极材料的结构特点,总结了单晶高镍三元正极材料常见的制备工艺,并探讨了近年来材料性能改善的主要策略,可为高性能单晶高镍三元正极材料的规模化生产提供借鉴和参考。

基于STM32的锂电池电量状态监测系统设计

提出了一种基于STM32主控和INA226电流电压检测芯片的氢气燃料电池供电的24 V锂电池电量状态(SoC)监测系统。通过INA226芯片采集锂电池的内部数据,监视分流压降和总线电源电压,实现了对锂电池电量状态的精确监测。详细介绍了锂电池电量状态监测系统的总体设计方案,以及STM32主控和INA226监测模块的电路设计和程序设计。通过实验验证,该系统能够有效地监测锂电池的电量状态,为氢气燃料电池供电系统的稳定运行提供了可靠的保障。

基于STM32单片机的太阳能自动跟踪锂电池充电系统设计

随着经济全球化和世界经济的迅猛发展,人们对煤炭、石油等传统能源的需求越来越高,但该类资源不仅储藏有限,而且容易污染环境。与此同时,以太阳能为代表的新能源逐渐进入人们的视野。在此背景下,为进一步提高太阳能的利用率,文章提出一种基于STM32单片机的太阳能自动跟踪锂电池充电系统的设计方案,利用光照传感器采集四个方向的光照强度将其转换为电信号,通过AD转换将电信号转化为数字信号,再由STM32单片机进行数据处理分析,并根据四个方向的光照强度驱动电机旋转,使太阳能电池板与太阳光尽量保持垂直,最大限度提高太阳能的吸收效率。

基于单频阻抗的锂离子电池热失控分级预警

潜在的热失控风险,特别是过充电,可能会引发锂离子电池的安全事故。以电化学阻抗谱(EIS)为基础,采用单频阻抗X_(1Hz)和X_(400Hz)实现电池内部阻抗的实时检测。在不同充电倍率、环境温度和健康状态下进行验证,特征阻抗表现出很好的稳定性。基于X_(1Hz)和X_(400Hz)的单频阻抗,提出一种热失控安全分级预警方法,并验证该方法的可靠性。该方法的最后一级预警可在热失控前5 min以上发出安全预警。