Regulating the Solvation Structure of Li^(+) Enables Chemical Prelithiation of Silicon-Based Anodes Toward High-Energy Lithium-Ion Batteries

The solvation structure of Li^(+) in chemical prelithiation reagent plays a key role in improving the low initial Coulombic efficiency(ICE) and poor cycle performance of silicon-based materials. Never theless, the chemical prelithiation agent is difficult to dope active Li^(+) in silicon-based anodes because of their low working voltage and sluggish Li^(+) diffusion rate. By selecting the lithium–arene complex reagent with 4-methylbiphenyl as an anion ligand and 2-methyltetrahydrofuran as a solvent, the as-prepared micro-sized Si O/C anode can achieve an ICE of nearly 100%. Interestingly, the best prelithium efficiency does not correspond to the lowest redox half-potential(E_(1/2)), and the prelithiation efficiency is determined by the specific influencing factors(E_(1/2), Li^(+) concentration, desolvation energy, and ion diffusion path). In addition, molecular dynamics simulations demonstrate that the ideal prelithiation efficiency can be achieved by choosing appropriate anion ligand and solvent to regulate the solvation structure of Li^(+). Furthermore, the positive effect of prelithiation on cycle performance has been verified by using an in-situ electrochemical dilatometry and solid electrolyte interphase film characterizations.

Achieving stable K-storage performance of carbon sphere-confined Sb via electrolyte regulation

Potassium-ion batteries(PIBs)have been considered as one of the most promising alternatives to lithiumion batteries(LIBs)in view of their competitive energy density with significantly reduced product cost.Moreover,alloy-type materials are expected as a high-performance anode of PIBs thanks to their intrinsic chemical stability as well as high theoretical specific capacity.Unfortunately,the serious incompatibility between alloy-type active materials and electrolytes,especially for the formation of unstable solidelectrolyte interfacial(SEI)films,often leads to insufficient cycle life.Herein,the formation mechanism of SEI films in the K-storage systems based on carbon sphere confined Sb anode(Sb@CS)were investigated in commercially available electrolytes.Physical characterizations and theoretical calculation revealed that the solvents in the dilute electrolyte of 0.8 M KPF_(6)/EC+DEC were excessively decomposed on the interface to generate unstable SEI and thus result in inferior K-storage stability.On the contrary,a salt-concentrated electrolyte(3 M KFSI/DME)can generate inorganic-dominated stable SEI due to the preferential decomposition of anions.As a result,the prepared Sb@CS in the matched 3 M KFSI/DME electrolyte delivered a high reversible capacity of 467.8 m A h g^(-1)after 100 cycles at 100 m A g^(-1),with a slow capacity decay of 0.19%per cycle from the 10th to the 100th cycle.These findings are of great significance for revealing the interfacial reaction between electrodes and electrolytes as well as improving the stability of Sb-based anode materials for PIBs.

Thermally Chargeable Proton Capacitor Based on Redox-Active Effect for Energy Storage and Low-Grade Heat Conversion

Thermal energy is abundantly available in our daily life and industrial production,and especially,low-grade heat is often regarded as a byproduct.Collecting and utilizing this ignored energy by low-cost and simple technologies may become a smart countermeasure to relieve the energy crisis.Here,a unique device has been demonstrated to achieve high value-added conversion of low-grade heat by introducing redox-active organic alizarin(AZ)onto N-doped hollow carbon nanofibers(N–HCNF)surface.As-prepared N–HCNF/AZ can deliver a high specific capacitance of 514.3 F g^(-1)(at 1 A g^(-1))and an outstanding rate capability of 60.3%even at 50 A g^(-1).Meanwhile,the assembled symmetric proton capacitor can deliver a high energy density of 28.0 Wh kg^(-1) at 350.0 W kg^(-1) and a maximum power density of 35.0 kW kg^(-1) at 17.0 Wh kg^(-1).Significantly,the thermally chargeable proton capacitors can attain a surprisingly high Seebeck coefficient of 15.3 mV K^(-1) and a power factor of 6.02µW g^(-1).Taking advantage of such high performance,a satisfying open-circuit voltage of 481.0 mV with a temperature difference of 54 K is achieved.This research provides new insights into construction of high value-added energy systems requiring high electrochemical performances.

Solvation Engineering via Fluorosurfactant Additive Toward Boosted Lithium-Ion Thermoelectrochemical Cells

Lithium-ion thermoelectrochemical cell(LTEC), featuring simultaneous energy conversion and storage, has emerged as promising candidate for low-grade heat harvesting. However, relatively poor thermosensitivity and heat-to-current behavior limit the application of LTECs using LiPF_6 electrolyte. Introducing additives into bulk electrolyte is a reasonable strategy to solve such problem by modifying the solvation structure of electrolyte ions. In this work, we develop a dual-salt electrolyte with fluorosurfactant(FS) additive to achieve high thermopower and durability of LTECs during the conversion of low-grade heat into electricity. The addition of FS induces a unique Li~+ solvation with the aggregated double anions through a crowded electrolyte environment,resulting in an enhanced mobility kinetics of Li~+ as well as boosted thermoelectrochemical performances. By coupling optimized electrolyte with graphite electrode, a high thermopower of 13.8 mV K^(-1) and a normalized output power density of 3.99 mW m^(–2) K^(–2) as well as an outstanding output energy density of 607.96 J m^(-2) can be obtained.These results demonstrate that the optimization of electrolyte by regulating solvation structure will inject new vitality into the construction of thermoelectrochemical devices with attractive properties.

Electrochemical Proton Storage:From Fundamental Understanding to Materials to Devices

Simultaneously improving the energy density and power density of electrochemical energy storage systems is the ultimate goal of electrochemical energy storage technology.An effective strategy to achieve this goal is to take advantage of the high capacity and rapid kinetics of electrochemical proton storage to break through the power limit of batteries and the energy limit of capacitors.This article aims to review the research progress on the physicochemical properties,electrochemical performance,and reaction mechanisms of electrode materials for electrochemical proton storage.According to the different charge storage mechanisms,the surface redox,intercalation,and conversion materials are classified and introduced in detail,where the influence of crystal water and other nanostructures on the migration kinetics of protons is clarified.Several reported advanced full cell devices are summarized to promote the commercialization of electrochemical proton storage.Finally,this review provides a framework for research directions of charge storage mechanism,basic principles of material structure design,construction strategies of full cell device,and goals of practical application for electrochemical proton storage.

All-Climate Aluminum-Ion Batteries Based on Binder-Free MOF-Derived FeS_(2)@C/CNT Cathode

Aluminum-ion batteries(AIBs)are promising next-generation batteries systems because of their features of low cost and abundant aluminum resource.However,the inferior rate capacity and poor all-climate performance,especially the decayed capacity under low temperature,are still critical challenges toward high-specific-capacity AIBs.Herein,we report a binder-free and freestanding metal-organic framework-derived FeS_(2)@C/carbon nanotube(FeS_(2)@C/CNT)as a novel all-climate cathode in AIBs working under a wide temperature window between−25 and 50℃ with exceptional flexibility.The resultant cathode not only drastically suppresses the side reaction and volu-metric expansion with high capacity and long-term stability but also greatly enhances the kinetic process in AIBs with remarkable rate capacity(above 151 mAh g^(−1) at 2 A g^(−1))at room temperature.More importantly,to break the bottleneck of the inherently low capacity in graphitic material-based all-climate AIBs,the new hierarchical conductive composite FeS_(2)@C/CNT highly promotes the all-climate performance and delivers as high as 117 mAh g^(−1) capacity even under−25°C.The well-designed metal sulfide electrode with remarkable performance paves a new way toward all-climate and flexible AIBs.

Transactions of Nanjing University of Aeronautics & Astronautics Information for Contributors

Transactions of Nanjing University of Aeronautics&Astronautics(TNUAA)is a bimonthly journal facing international academic community.Emphasizing prompt and effective dissemination of key data and new scientific insights,TNUAA offers publication of new experimental and theoretical papers bearing on applications to all branches of aeronautics,astronautics and civil aviation.

A facile finger-paint physical modification for bilateral electrode/electrolyte interface towards a stable aqueous Zn battery

Since the electrode/electrolyte interface(EEI)is the main redox center of electrochemical processes,proper manipulation of the EEI microenvironment is crucial to stabilize interfacial behaviors.Here,a finger-paint method is proposed to enable quick physical modification of glass-fiber separator without complicated chemical technology to modulate EEI of bilateral electrodes for aqueous zinc-ion batteries(ZIBs).An elaborate biochar derived from Aspergillus Niger is exploited as the modification agent of EEI,in which the multi-functional groups assist to accelerate Zn^(2+)desolvation and create a hydrophobic environment to homogenize the deposition behavior of Zn anode.Importantly,the finger-paint interface on separator can effectively protect cathodes from abnormal capacity fluctuation and/or rapid attenuation induced by H_(2)O molecular on the interface,which is demonstrated in modified MnO_(2),V_(2)O_(5),and KMn HCF-based cells.The as-proposed finger-paint method opens a new idea of bilateral interface engineering to facilitate the access to the practical application of the stable zinc electrochemistry.

Recent Progress and Prospects on Dendrite-free Engineerings for Aqueous Zinc Metal Anodes

Rechargeable zinc-ion batteries with mild aqueous electrolytes are one of the most promising systems for large-scale energy storage as a result of their inherent safety,low cost,environmental-friendliness,and acceptable energy density.However,zinc metal anodes always suffer from unwanted dendrite growth,leading to low Coulombic efficiency and poor cycle stability and during the repeated plating/stripping processes,which substantially restrict their further development and application.To solve these critical issues,a lot of research works have been dedicated to overcoming the drawbacks associated with zinc metal anodes.In this overview,the working mechanisms and existing issues of the zinc metal anodes are first briefly outlined.Moreover,we look into the ongoing processes of the different strategies for achieving highly stable and dendrite-free zinc metal anodes,including crystal engineering,structural engineering,coating engineering,electrolyte engineering,and separator engineering.Finally,some challenges being faced and prospects in this field are provided,together with guiding significant research directions in the future.

Dual-filler reinforced PVDF-HFP based polymer electrolyte enabling high-safety design of lithium metal batteries

Despite the high energy density of lithium metal batteries(LMBs),their application in rechargeable batteries is still hampered due to insufficient safety.Here,we present a novel flame-retardant solid-state electrolyte based on polyvinylidene fluoride-hexafluoropropylene(PVDF-HFP)with nano SiO_(2)aerogel as an inert filler but Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)as an auxiliary component to enhance the ion conductivity.The introduction of SiO_(2)aerogels imparts the polymer electrolyte with exceptional thermal stability and flame retardancy.Simultaneously,the interaction between hydroxyl groups of SiO_(2)particles and PVDF-HFP creates a strong cross-linking structure,enhancing the mechanical strength and stability of the electrolyte.Furthermore,the presence of SiO_(2)aerogel and LLZTO facilitates the dissociation of lithium salts through Lewis acid-base interactions,resulting in a high ionic conductivity of 1.01×10^(−3)S·cm^(−1)and a wide electrochemical window of~5.0 V at room temperature for the prepared electrolytes.Remarkably,the assembled Li|Li cell demonstrates the excellent resistance to lithium dendrite and runs stablly for over 1500 h at a current density of 0.25 mA·cm^(−2).Thus,we prepare a pouch cell with high safety,which can work normally after short-circuiting under the external folding and cutting.

Regulating surface state of WO3 nanosheets by gamma irradiation for suppressing hydrogen evolution reaction in electrochemical N2 fixation

Realizing the reduction of N2 to NH3 at low temperature and pressure is always the unremitting pursuit of scientists and then electrochemical nitrogen reduction reaction offers an intriguing alternative.Here,we develop a feasible way,gamma irradiation,for constructing defective structure on the surface of WO3 nanosheets,which is clearly observed at the atomic scale by high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).The abundant oxygen vacancies ensure WO3 nanosheets with a Faradaic efficiency of 23%at−0.3 V vs.RHE.Moreover,we start from the regulation of the surface state to suppress proton availability towards hydrogen evolution reaction(HER)on the active site and thus boost the selectivity of nitrogen reduction.

Niobium Tungsten Oxide in a Green Water‑in‑Salt Electrolyte Enables Ultra‑Stable Aqueous Lithium‑Ion Capacitors

Aqueous hybrid supercapacitors are attracting increasing attention due to their potential low cost,high safety and eco-friendliness.However,the narrow operating potential window of aqueous electrolyte and the lack of suitable negative electrode materials seriously hinder its future applications.Here,we explore high concentrated lithium acetate with high ionic conductivity of 65.5 mS cm−1 as a green“water-in-salt”electrolyte,providing wide voltage window up to 2.8 V.It facilitates the reversible function of niobium tungsten oxide,Nb18W16O93,that otherwise only operations in organic electrolytes previously.The Nb18W16O93 with lithium-ion intercalation pseudocapacitive behavior exhibits excellent rate performance,high areal capacity,and ultra-long cycling stability.An aqueous lithium-ion hybrid capacitor is developed by using Nb18W16O93 as negative electrode combined with graphene as positive electrode in lithium acetate-based“water-in-salt”electrolyte,delivering a high energy density of 41.9 W kg−1,high power density of 20,000 W kg−1 and unexceptionable stability of 50,000 cycles.

Biomass-Derived Nitrogen and Sulfur Co-Doped 3D Carbon Networks with Interconnected Meso-Microporous Structure for High-Performance Supercapacitors

Three-dimensional(3D)carbon networks have been explored as promising capacitive materials thanks to their unique structural features such as large ion-accessible surface area and interconnected porous networks,thus enhancing both ions and electrons transport.Here,sustainable bacterial cellulose(BC)is used both precursor and template for facile synthesis of free-standing N,S-codoped 3Dcarbon networks(a-NSC)by the pyrolysis and activation of polyrhodanine coated BC.The synthesized a-NSC shows highly conductive interconnected porous networks(24S·cm^(-1)),large surface area(1 420m^2·g^(-1))with hierarchical meso-microporosity,and high-level heteroatoms codoping(N:3.1%in atom,S:3.2%in atom).Benefitting from these,a-NSC as binder-free electrode exhibits an ultrahigh specific capacitance of 340F·g^(-1)(24μF·cm^(-2))at the current density of 0.5A·g^(-1)in 6MKOH electrolyte,high-rate capability(71%at 20A·g^(-1))and excellent cycle stability.Furthermore,the assembled symmetrical supercapacitor displays a much short time constant of 0.35sin 1MTEABF4/AN electrolyte,obtaining a maximum energy density of 32.1W·h·kg^(-1 )at power density of 637W·kg^(-1).The in situ multi-heteroatoms doping enables biocellulose-derived carbon networks to exploit its full potentials in energy storage applications,which can be extended to other dimensional carbon nanostructures.

Nanohollow Carbon for Rechargeable Batteries:Ongoing Progresses and Challenges

Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.

Amorphous porous sulfides nanosheets with hydrophilic/aerophobic surface for high-current-density water splitting

The rational construction of electrocatalysts with desired features is significant but challenging for superior water splitting at high current density. Herein, amorphous Co Ni S nanosheets are synthesized on nickel foam(NF) through a facile structure evolution strategy and present advanced performance at high current densities in water splitting. The high catalytic activity can be attributed to the sufficient active sites exposed by the flexible amorphous configuration. Moreover, the hydrophilicity and aerophobicity of a-CoNiS/NF promote surface wettability of the self-supporting electrode and avoid the aggregation of bubbles, which expedites the diffusion of electrolyte and facilitates the mass transfer. As a result, the optimized electrode demonstrates low overpotentials of 289 and 434 m V at 500 m A/cm^(2) under alkaline conditions for hydrogen evolution reaction(HER) and oxygen evolution reaction(OER), respectively. Impressively, an electrolytic water splitting cell assembled by bifunctional a-Co Ni S/NF operates with a low cell voltage of 1.46 V@10 mA/cm^(2) and reaches 1.79 V at 500 mA/cm^(2). The strategy sheds light on a competitive platform for the reasonable design of non-precious-metal electrocatalysts under high current density.

多维分层CoS_(2)@MXene作为三功能电催化剂应用于锌-空气电池和水分解

设计高效的非贵金属催化剂对于电催化能量转化过程,比如ORR,OER和HER至关重要.多功能的催化剂需要复杂且耗时的材料设计,本文通过简单水热生长和硫化结合的策略构建了MXene基底结合CoS_(2)活性位点的高效催化界面.由一维CoS_(2)纳米线和二维MXene纳米片组成的多维CoS_(2)@MXene电催化剂,具有分层结构(大的比表面积和丰富的活性位点),优化的空间电子结构(高本征活性)和高结合强度(优异的稳定性).因此,在ORR,OER和HER催化过程中都展示了优异的电催化活性,ORR的半波电位是0.80 V,OER和HER达到10 mA cm^(-2)的过电位分别为270和175 mV.对于电化学水分解,CoS_(2)@MXene需要1.63 V就能达到10 mA cm^(-2).以CoS_(2)@MXene为空气电极组装的固态锌空气电池也展示了低充放电电压差(在1 mA cm^(-2)为0.53 V)和高稳定性(能循环60圈,20 h),且两节串联的固态锌空气电池即可驱动水分解.因此,这项工作为多功能催化剂的设计和应用提供了新思路.

Recent advances and perspectives on prelithiation strategies for lithium-ion capacitors

Lithium-ion capacitors(LICs),consisting of a capacitor-type material and a battery-type material together with organic electrolytes,are the state-of-the-art electrochemical energy storage devices compared with supercapacitors and batteries.Owing to their unique characteristics,LICs received a lot of attentions,and great progresses have been achieved,especially in the exploration of cathode and anode materials.Prelithiation techniques are regarded as indispensable procedures for LICs systems,which can compensate for the initial irreversible capacity loss,increase the Li^(+)concentration in the electrolyte,raise the working voltage and resolve the safety and cycle stability issues;however,its research progress is slow,and there is not enough attention until now.In this overview,we look into the ongoing processes on the recent development of prelithiation technologies,especially in organic electrolyte consumption-type LICs.In particular,some prelithiation strategies for LICs are summarized and discussed in detail,including the ex situ electrochemical method,in situ electrochemical method,and cathode prelithiation additives method.Moreover,we propose some unresolved challenges and prospects for prelithiation technologies from the basic research ideas and future key research directions.This work aims to bring up new insights to reassess the significance of premetallation strategies for advanced hybrid-ion capacitors based on the currently proposed prelithiation strategies.

Single atom site conjugated copper polyphthalocyanine assisted carbon nanotubes as cathode for reversible Li-CO_(2) batteries

Recently,Li-CO_(2) battery has gradually become a research hotspot due to its high discharge capacity,energy density and environmental benefits.However,it has been an important problem for researchers because of its slow decomposition kinetics and difficult to generalize to practical application.Herein,we prepared copper polyphthalocyanine-carbon nanotubes composites(CuPPc-CNTs)by solvothermal in-situ polymerization of copper phthalocyanine on the surface of carbon nanotubes as cathode for reversible Li-CO_(2) batteries,which exhibits a high discharge capacity of 18,652.7 mAh·g^(-1) at current density of 100 mA·g^(-1),1.64 V polarization at 1,000 mA·g^(-1),and a stable cycles number of 160 is close to 1,630 h of charge-discharge process at 200 mA·g^(-1).Copper polyphthalocyanine has highly efficient copper single-atom catalytic sites with excellent CO_(2) adsorption and activation,while carbon nanotubes provide a conductive network.The synergistic effect of the two compounds enables it to have excellent catalytic activity.The density functional theory(DFT)calculation proved that the addition of copper polyphthalocyanine significantly improved the CO_(2) adsorption and activation process.This study provides an opportunity for the research of covalent organic polymers(COPs)single-atom catalyst in Li-CO_(2) battery field.

Vanadium nitride nanoparticles embedded in carbon matrix with pseudocapacitive behavior for high performance lithium-ion capacitors

Lithium-ion capacitors(LICs)have attracted wide attention due to their potential of achieving merits of high-power output as well as high energy density.How-ever,the key issue of kinetics mismatch between anode and cathode hinders the electrochemical performance of LICs.Therefore,a vanadium nitride composite with nanoparti-cles embedded in carbon matrix(VN-C)was prepared as an efficiently pseudocapacitive anode material with high electronic conductivity and fast Li-ion diffusion rate.The VN-C composites were synthesized through one-step ammonia heating treatment at different temperatures among which the sample annealed at 600℃exhibits high specific capacity(513 mAh·g^(-1)at 0.1 A·g^(-1)),outstanding rate performance(~300 mAh·g^(-1)at 10 A·g^(-1)),and excellent cyclic steadiness(negligible capacity decay over 2000 cycles)in half-cell devices.A high-performance lithium-ion capacitor device was also fabricated by using VN-C-600 as the anode and activated carbon as the cath-ode,delivering a maximum energy density of 112.6 Wh·kg^(-1)and an extreme power density of 10 kW·kg^(-1).

B-doped SiO_(x) composite with three dimensional conductive network for high performance lithium-ion battery anode

Currently,the practical application of SiO_(x) still has a huge hindrance in the area of lithium ion battery,because it is unable to achieve an effective contact with surrounding conducting materials,resulting in failure to form lithium ion migration tunnels.In this work,we presented a facile method to synthesize the B-doped SiOx composite by adhering SiO_(x) particles with MWCNT(multi-walled carbon nanotube)under the assistance of lithium metaborate(LiBO_(2)).LiBO_(2),as a sintering aid,not only can react with SiO_(x) to form a compacted framework,but also build a three-dimensional(3D)conductive network for ions transportation.Furthermore,B-SiO_(x)@CNT@LBO anode delivers a remarkable lithium storage performance in terms of long cycles and high rate capability.A full cell coupled with NCM622 cathode achieves a high energy density of 429.5 Wh kg^(-1) based on the total mass of cathode.