Research progress on construction and energy storage performance of MXene heterostructures

MXenes are a family of two-dimensional (2D) transition metal carbides, carbonitrides/nitrides with superior physical and chemical properties, which have attracted extensive attention since the discovery in 2011. The impressive electrochemical activity of MXene makes it one of the most potential electrode materials in rechargeable batteries and supercapacitors. However, single-component MXene electrodes are difficult to achieve high specific capacity, efficient ion/electron transport, and high stability compatibility in an electrochemical environment. Studies have shown that it is an effective method to introduce nanomaterials between MXene layers to construct heterostructures and to improve the electrochemical performance through the synergistic effect among the components in the heterostructures. The introduction of nanomaterials can effectively suppress the restacking of MXene nanosheets, shorten the diffusion path of ions and promote the electrolyte transport, which is beneficial to enhance the rate performance of MXene;moreover, the excellent mechanical flexibility of MXene can reduce the volume expansion of nanomaterials during charge/discharge, thereby effectively protecting the integrity of the electrode structure and improving the cycling stability. Therefore, in this review, combined with theoretical calculations, we summarize the recent advances of MXene heterostructures in terms of synthesis strategies and energy storage applications, including supercapacitors, metal-ions batteries (Li, Na, K, Mg, Zn, Al) and metal anode protection. Furthermore, potential challenges and application perspectives for MXene heterostructures are also outlined.

P(VDF-HFP)-poly(sulfur-1,3-diisopropenylbenzene) functional polymer electrolyte for lithium–sulfur batteries

Lithium–sulfur(Li–S)battery as a high-energy density electrochemical energy storage system has attracted many researchers’attention.However,the shuttle effect of Li–S batteries and the challenges associated with lithium metal anode caused poor cycle performance.In this work,the organosulfide poly(sulfur-1,3-diisopropenylbenzene)(PSD)was prepared as cathode material and additive of P(VDFHFP)polymer electrolyte(P(VDF-HFP)).It was verified that P(VDF-HFP)polymer electrolyte with 10%PSD(P(VDF-HFP)-10%PSD)showed a higher ionic conductivities than that of liquid electrolyte up to2.27×10-3 S cm-1 at room temperature.The quasi-solid-state Li-S batteries fabricated with organosulfide cathode material PSD and P(VDF-HFP)based functional polymer electrolyte delivered good cycling stability(780 m Ah g-1 after 200 th cycle at 0.1 C)and rate performance(613 m Ah g-1 at 1 C).The good cycling performance could be attributed to the synergistic effect of components,including the interaction between polysulfides and polymer main chain in the organosulfide cathode,the sustained organic/inorganic hybrid stable SEI layer formed by polymer electrolyte additive PSD,the improved cathode/electrolyte interface and the good affinity between P(VDF-HFP)based functional polymer electrolyte and Li metal surface.This strategy herein may provide a new route to fabricate high-performance Li–S batteries through the organosulfide cathode and functional polymer electrolyte.

Nitrogen-rich hierarchically porous carbon foams as high-performance electrodes for lithium-based dual-ion capacitor

Nitrogen-rich porous carbonaceous materials have shown great potential in energy storage and conversion applications due to their facile fabrication,high electronic conductivity,and improved hydrophilic property.Herein,three-dimensional porous N-rich carbon foams are fabricated through a one-step carbonization-activation method of the commercial melamine foam,and displaying hierarchically porous structure(macro-,meso-,and micro-pores),large surface area(1686.5 m2 g^-1),high N-containing level(3.3 at%),and excellent compressibility.The as-prepared carbon foams as electrodes for quasi-solid-state supercapacitors exhibit enhanced energy storage ability with 210 F g^-1 and 2.48c at 0.1 A g^-1,and150 F g^-1 and 1.77 F cm^-2 at 1 A g^-1,respectively.Moreover,as an electrode for lithium-based dual-ion capacitor,this distinctive porous carbon also delivers remarkable specific capacitance with 143.6 F g^-1 at0.1 A g^-1 and 116.2 F g^-1 at 1 A g^-1.The simple preparation method and the fascinating electrochemical performance endow the N-rich porous carbon foams great prospects as high-performance electrodes for electrochemical energy storage.

Enhancing interfacial stability in solid-state lithium batteries with polymer/garnet solid electrolyte and composite cathode framework

The solid-state lithium battery is considered as an ideal next-generation energy storage device owing to its high safety,high energy density and low cost.However,the poor ionic conductivity of solid electrolyte and low interfacial stability has hindered the application of solid-state lithium battery.Here,a flexible polymer/garnet solid electrolyte is prepared with poly(ethylene oxide),poly(vinylidene fluoride),Li6.75La3 Zr1.75Ta0.25O12,lithium bis(trifluoromethanesulfonyl)imide and oxalate,which exhibits an ionic conductivity of 2.0 ×10^(-4) S cm^(-1) at 55℃,improved mechanical property,wide electrochemical window(4.8 V vs.Li/Li+),enhanced thermal stabilities.Tiny acidic OX was introduced to inhibit the alkalinity reactions between Li6.75La3 Zr1.75Ta0.25O12 and poly(vinylidene fluoride).In order to improve the interfacial stability between cathode and electrolyte,an Al2 O3@LiNi0.5Co0.2Mn0.3O2 based composite cathode framework is also fabricated with poly(ethylene oxide) polymer and lithium salt as additives.The solid-state lithium battery assembled with polymer/garnet solid electrolyte and composite cathode framework demonstrates a high initial discharge capacity of 150.6 mAh g^(-1) and good capacity retention of 86.7% after 80 cycles at 0.2 C and 55℃,which provides a promising choice for achieving the stable electrode/electrolyte interfacial contact in solid-state lithium batteries.

Metallic phase W_(0.9)Mo_(0.1)S_(2)for high-performance anode of sodium ion batteries through suppressing the dissolution of polysulfides

WS_(2)with layered graphite-like structure as anode for sodium ion batteries has high specific capacity.However,the poor cycling performance and rate capability of WS_(2)caused by the low electronic conductivity and structure changes during cycles inhibit its practical application.Herein,metallic phase(1T)W_(x)Mo_(1−x)S2(x=1,0.9,0.8 and 0.6)with high electronic conductivity and expanded interlayer spacing of 0.95 nm was directly prepared via a simple hydrothermal method.Specially,1T W_(0.9)Mo_(0.1)S_(2)as anode for sodium ion batteries displays high capacities of 411 mAh g^(-1)at 0.1 A g^(-1)after 180 cycles and 262 mAh g^(-1)at 1 A g^(-1)after 280 cycles and excellent rate capability(245 mAh g^(-1)at 5 A g^(-1)).The full cell based on Na_(3)V_(2)(PO_(4))_(2)O_(2)F/C cathode and 1T W_(0.9)Mo_(0.1)S_(2)anode also exhibits high capacity and good cycling performance.The irreversible electrochemical reaction of 1T W_(0.9)Mo_(0.1)S_(2)with Na ions during first few cycles results in the main products of W-Mo alloy and S.The strong adsorption of W-Mo alloy with polysulfides can effectively suppress the dissolution and shuttle effect of polysulfides,which ensures the excellent cycling performance of 1T W_(0.9)Mo_(0.1)S_(2).

Enabling high-performance all-solid-state lithium batteries with high ionic conductive sulfide-based composite solid electrolyte and ex-situ artificial SEI film

All-solid-state lithium batteries(ASSLBs) employing sulfide electrolyte and lithium(Li) anode have received increasing attention due to the intrinsic safety and high energy density.However,the thick electrolyte layer and lithium dendrites formed at the electrolyte/Li anode interface hinder the realization of high-performance ASSLBs.Herein,a novel membrane consisting of Li_(6)PS_(5) Cl(LPSCl),poly(ethylene oxide)(PEO) and Li-salt(LiTFSI) was prepared as sulfide-based composite solid electrolyte(LPSCl-PEO3-LiTFSI)(LPSCl:PEO=97:3 wt/wt;EO:Li=8:1 mol/mol),which delivers high ionic conductivity(1.1 × 10^(-3) S cm^(-1)) and wide electrochemical window(4.9 V vs.Li^(+)/Li) at 25 ℃.In addition,an ex-situ artificial solid electrolyte interphase(SEI) film enriched with LiF and Li3 N was designed as a protective layer on Li anode(Li(SEI)) to suppress the growth of lithium dendrites.Benefiting from the synergy of sulfide-based composite solid electrolyte and ex-situ artificial SEI,cells of S-CNTs/LPSCI-PEO3-LiTFSI/Li(SEI) and Al_(2)O_(3)@LiNi_(0.5)Co_(0.3)Mn_(0.2)O_(2)/LPSCl-PEO3-LiTFSI/Li(SEI) are assembled and both exhibit high initial discharge capacity of 1221.1 mAh g^(-1)(135.8 mAh g^(-1)) and enhanced cycling stability with 81.6% capacity retention over 200 cycles at 0.05 C(89.2% over 100 cycles at 0.1 C).This work provides a new insight into the synergy of composite solid electrolyte and artificial SEI for achieving high-performance ASSLBs.

Porous polymer electrolytes for long-cycle stable quasi-solid-state magnesium batteries

The development of applicable electrolytes is the key point for high-performance rechargeable magnesium batteries(RMBs).The use of liquid electrolyte is prone to safety problems caused by liquid electrolyte leakage.Polymer-based gel electrolytes with high ionic conductivity,great flexibility,easy processing,and high safety have been studied by many scholars in recent years.In this work,a novel porous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membrane is prepared by a phase inversion method.By immersing porous PVDF-HFP membranes in MgCl2-AlCl3/TEGDME(Tetraethylene glycol dimethyl ether)electrolytes,porous PVDF-HFP based electrolytes(PPEs)are formed.The PPE exhibits a high ionic conductivity(4.72×10^(-4) S cm-1,25℃),a high liquid electrolyte uptake of 162%,as well as a wide voltage window(3.1 V).The galvanostatic cycling test of Mg//Mg symmetric cell with PPE reveals that the reversible magnesium ion(Mg^(2+))plating/stripping occurs at low overpotentials(~0.13 V).Excellent long cycle stability(65.5 mAh g^(-1) over 1700 cycles)is achieved for the quasisolid-state RMB assembled with MoS2/C cathode and Mg anode.Compared with the liquid electrolyte,the PPE could effectively reduce the side reactions and make Mg^(2+)plating/stripping more uniformly on the Mg electrode side.This strategy herein provides a new route to fabricate high-performance RMB through suitable cathode material and polymer electrolyte with excellent performance.

Manipulating interfacial stability of LiNi0.5Co0.3Mn0.2O2 cathode with sulfide electrolyte by nanosized LLTO coating to achieve high-performance all-solid-state lithium batteries

All-solid-state lithium batteries(ASSLBs) based on sulfide solid-state electrolytes and high voltage layered oxide cathode are regarded as one of the most promising candidates for energy storage systems with high energy density and high safety.However,they usually suffer poor cathode/electrolyte interfacial stability,severely limiting their practical applications.In this work,a core-shell cathode with uniformly nanosized Li0.5La0.5TiO3(LLTO) electrolyte coating on LiNi0.5Co0.3Mn0.2O2(NCM532) is designed to improve the cathode/electrolyte interface stability.Nanosized LLTO coating layer not only significantly boosts interfacial migration of lithium ions,but also efficiently alleviates space-charge layer and inhibits the electrochemical decomposition of electrolyte.As a result,the assembled ASSLBs with high mass loading(9 mg cm-2)LLTO coated NCM532(LLTO@NCM532) cathode exhibit high initial capacity(135 mAh g^(-1)) and excellent cycling performance with high capacity retention(80% after 200 cycles) at 0.1 C and 25℃.This nanosized LLTO coating layer design provides a facile and effective strategy for constructing high performance ASSLBs with superior interfacial stability.

Cationic potential:An effective descriptor for rational design of layered oxides for sodium-ion batteries

Sodium-ion batteries are very promising in large-scale energy storage.The exploration of Na layered oxides as cathode materials for Na ion batteries usually consumes much resource,while the performances of Na layered oxides are dominated by their crystal structures.Therefore,it is highly desired to predict the stacking mode of the target oxides in advance:whether O3-type with higher ordered structure and stability,or P2-type with more Na content.For this purpose density functional theory computations do not work.Very recently,Hu's group and international collaborators have proposed a cationic potential to provide a very timely,effective,and accurate criterion to predict the stacking mode of Na layered oxides(Science,370(2020)708-711).Under the guidance of the cationic potential phase map,Na layered oxides could be rationally designed.Here we would like to highlight the progress that novel Na layered oxides could be obtained with the combination of large specific capacity,high power density and good cycling stability.

A review of solid-state lithium metal batteries through in-situ solidification

High-energy-density lithium metal batteries are the next-generation battery systems of choice,and replacing the flammable liquid electrolyte with a polymer solid-state electrolyte is a prominent conduct towards realizing the goal of high-safety and high-specific-energy devices.Unfortunately,the inherent intractable problems of poor solid-solid contacts between the electrode/electrolyte and the growth of Li dendrites hinder their practical applications.The in-situ solidification has demonstrated a variety of advantages in the application of polymer electrolytes and artificial interphase,including the design of integrated polymer electrolytes and asymmetric polymer electrolytes to enhance the compatibility of solid–solid contact and compatibility between various electrolytes,and the construction of artificial interphase between the Li anode and cathode to suppress the formation of Li dendrites and to enhance the high-voltage stability of polymer electrolytes.This review firstly elaborates the history of in-situ solidification for solid-state batteries,and then focuses on the synthetic methods of solidified electrolytes.Furthermore,the recent progress of in-situ solidification technology from both the design of polymer electrolytes and the construction of artificial interphase is summarized,and the importance of in-situ solidification technology in enhancing safety is emphasized.Finally,prospects,emerging challenges,and practical applications of in-situ solidification are envisioned.

A three-way electrolyte with ternary solvents for high-energy-density and long-cycling lithium-sulfur pouch cells

Lithium–sulfur(Li–S)batteries promise high-energy-density potential to exceed the commercialized lithiumion batteries but suffer from limited cycling lifespan due to the side reactions between lithium polysulfides(LiPSs)and Li metal anodes.Herein,a three-way electrolyte with ternary solvents is proposed to enable high-energy-density and long-cycling Li–S pouch cells.Concretely,ternary solvents composed of 1,2-dimethoxyethane,di-isopropyl sulfide,and 1,3,5-trioxane are employed to guarantee smooth cathode kinetics,inhibit the parasitic reactions,and construct a robust solid electrolyte interphase,respectively.The cycling lifespan of Li–S coin cells with 50μm Li anodes and 4.0 mg cm^(−2) sulfur cathodes is prolonged from88 to 222 cycles using the three-way electrolyte.Nano-heterogeneous solvation structure of LiPSs and organic-rich solid electrolyte interphase are identified to improve the cycling stability of Li metal anodes.Consequently,a 3.0 Ah-level Li–S pouch cell with the three-way electrolyte realizes a high energy density of 405 Wh kg^(−1) and undergoes 27 cycles.Thiswork affords a three-way electrolyte recipe for suppressing the side reactions of LiPSs and inspires rational electrolyte design for practical high-energy-density and long-cycling Li–S batteries.

A robust solid electrolyte interphase enabled by solvate ionic liquid for high-performance sulfide-based all-solid-state lithium metal batteries

All-solid-state lithium metal batteries(ASSLMBs)that incorporate solid electrolyte(SE)and lithium metal anode suggest considerable potential in addressing the security concerns and energy density limitation of conventional lithium-ion batteries(LIBs).However,the practical application of ASSLMBs is always restricted by the interfacial instability of lithium metal anode/electrolyte and inevitable lithium dendrites propagation in SE.Herein,a solvate ionic liquid is adopted to modify the interface stability of lithium metal anode/electrolyte and inhibit the growth of lithium dendrites via an in-situ formation of a robust solid electrolyte interphase(SEI)on the surface of lithium metal anode.Consequently,the ASSLMBs assembled with Li_(6)PS_(5)Cl(LPSCl)electrolyte,lithium metal anode that protected by robust SEI layer,and LiNbO_(3)@NCM622 cathode exhibit high initial capacity of 126.5 mAh·g^(−1)and improved cycling stability with a capacity retention of 80.3%over 60 cycles at 0.1 C.This work helps to provide a facile route for the design of robust SEI in the application of ASSLMBs.

Synergistically enabling the interface stability of lithium metal batteries with soft ionic gel and garnet-type Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)ceramic filler

Lithium metal batteries based on solid electrolytes are considered as promising candidates with high energy density and safety.However,the weak solid-solid contact between electrolyte and electrode can easily lead to interface instability and lithium ions discontinuous migration,which seriously reduces the electrochemical performance of the battery.Herein,we construct a soft gel interfacial layer to improve the stability of the solid-solid interface between electrolyte and electrode by means of polyester-based monomers and imidazole-based ionic liquids.Based on this,garnet-type Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)particles as inorganic ceramic filler were introduced in the layer to obtain composite electrolytes with high ionic conductivity(up to 1.1×10^(-3)S/cm at 25℃).As a result,the assembled lithium symmetric battery of Li|THCE-15%LLZTO|Li suggests excellent cycling stability with 700 h at 0.1 mA/cm^(2)at 50℃,and the lithium metal batteries of LFP|THCE-15%LLZTO|Li delivers high initial discharge capacity of 128.2 mA·h/g with capacity retain of 75.48%after 150 cycles at 2 C.This work paves a new route to build safe and stable lithium metal batteries with synergistic introduction of composite electrolytes between electrolyte and electrode using soft gel interfacial layer and inorganic filler.

Pr doped single-crystal LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)cathode enables high rate capability and cycle stability for lithium ion batteries

The massive application of single crystal(SC)ternary cathode material LiNi_(1-x-y)Mn_(x)Co_(y)O_(2)is largely restricted by the unsatisfactory rate capability which is caused by the sluggish Li+diffusion and structural instability.Herein,Pr^(3+),a large radius ion is introduced to single-crystal LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)to enhance Li^(+)conductivity and structural stability.With 0.4%Pr doping,the Li(Ni_(0.5)Mn_(0.3)Co_(0.2))_(0.996)Pr_(0.004)O_(2)cathode displays a capacity retention of 79.72%at 10 C,and a 98.17%capacity retention after 50 cycles at 25°C and 96.3%capacity retention after 50 cycles at 55°C within a 3.0–4.5 V voltage window.Electrochemical impedance spectroscopy confirms that the Pr doping can effectively lower the charge-transfer resistance and facilitate the transportation of Li^(+)on the surface of LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2).The Direct current internal resistance result implies that the structure of the Pr-doped cathode particles is more stable during cycling.In addition,differential scanning calorimetry measurements measurement combined with in situ X-ray diffraction confirms the thermo-stabilization effect of the Pr dopant.

Poly(ethylene carbonate)-based electrolytes with high concentration Li salt for all-solid-state lithium batteries

High-performance solid polymer electrolyte （SPE） has long been desired for the next-generation high energy density and safe rechargeable lithium batteries. A SPE composed of 80 wt% lithium bis（trifluo-romethanesulfonyl）imide （LiTFSI）, 20% poly（ethylene carbonate） （PEC） and a polyamide （PA） fiber membrane backbone was prepared by solution-casting method. This solid electrolyte exhibits quite high ionic conductivity and lithium ion transference number （t＋）, and excellent mechanical strength. The as-prepared solid electrolyte shows good wettability to porous electrodes during cycles, which is beneficial to form ionically conductive phase throughout porous electrodes. All-solid-state LiFePO4lLi cells assembled with the as-prepared solid electrolyte deliver a high initial discharge specific capacity of 125.7 mAh·g^-1 and good cycling stability at 55 ℃ （93.4% retention at 1C after 200 cycles）, and superior cycle performance. Outstanding electrochemical performance can be mainly ascribed to the improved ionic conductivity in the entire porous electrodes due to the good wettability of SPE.

Self-standing Na-storage anode of Fe2O3 nanodots encapsulated in porous N-doped carbon nanofibers with ultra-high cyclic stability

Ultrasmall y-Fe203 nanodots （- 3.4 nm） were homogeneously encapsulated in interlinked porous N-doped carbon nanofibers （labeled as Fe2O3@C） at a considerable loading （-51 wt.%） via an electrospinning technique. Moreover, the size and content of Fe2O3 could be controlled by adjusting the synthesis conditions. The obtained Fe203@C that functioned as a self-standing membrane was used directly as a binder- and current collector-free anode for sodium-ion batteries, displaying fascinating electrochemical performance in terms of the exceptional rate capability （529 mA.h.gq at 100 mA-g-1 compared with 215 mA-h-g-1 at 10,000 mA.g-1） and unprecedented cyclic stability （98.3% capacity retention over 1,000 cycles）. Furthermore, the Na-ion full cell constructed with the Fe2O3C anode and a P2-Na2/3Ni1/3Mn2/302 cathode also exhibited notable durability with 97.2% capacity retention after 300 cycles. This outstanding performance is attributed to the distinctive three-dimensional network structure of the very-fine Fe203 nanoparticles uniformly embedded in the interconnected porous N-doped carbon nanofibers that effectively facilitated electronic/ionic transport and prevented active materials pulverization/aggregation caused by volume change upon prolonged cycling. The simple and scalable preparation route, as well as the excellent electrochemical performance, endows the Fe2O3@C nanofibers with great prospects as high-rate and long-life Na-storage anode materials.

Challenges,interface engineering,and processing strategies toward practical sulfide-based all-solid-state lithium batteries

All-solid-state lithium batteries have emerged as a priority candidate for the next generation of safe and energy-dense energy storage devices surpassing state-of-art lithium-ion batteries.Among multitudinous solid-state batteries based on solid electrolytes(SEs),sulfide SEs have attracted burgeoning scrutiny due to their superior ionic conductivity and outstanding formability.However,from the perspective of their practical applications concerning cell integration and production,it is still extremely challenging to constructing compatible electrolyte/electrode interfaces and developing available scale processing technologies.This review presents a critical overview of the current underlying understanding of interfacial issues and analyzes the main processing challenges faced by sulfide-based all-solid-state batteries from the aspects of cost-effective and energy-dense design.Besides,the corresponding approaches involving interface engineering and processing protocols for addressing these issues and challenges are summarized.Fundamental and engineering perspectives on future development avenues toward practical application of high energy,safety,and long-life sulfide-based all-solid-state batteries are ultimately provided.

A scalable bio-inspired polydopamine-Cu ion interfacial layer for high-performance lithium metal anode

The growth of Li dendrites and the instability of the solid electrolyte in terphase(SEI)layer during plating/stripping has hin dered the practical applicati on of high-energy-density batteries based on a lithium metal anode.Building a stable interfacial layer is effective in preventing lithium corrosiion by the electrolyte and controlling the deposition of lithium metal.Here,we present a robust polydopamine-Cu ion(PDA-Cu^2+)coati ng layer formed by the aggregation of nanoparticles and Cu ions,which can be obtained by a subtle immersion strategy.We demonstrate that the PDA-Cu^2+ protective layer,with a unique structure comprising nanoparticles,can regulate and guide Li metal deposition,and together with Cu ions,forms a lubricating surface to facilitate uniform Li ion diffusion and induce stable SEI layer formation.Li anodes with this PDA-Cu^2+layer modification ultimately achieve higher Coulombic efficiencies,which are consistently stable for over 650 cycles at 0.5 mA·cm^-2 without Li dendrites.The introduced PDA-Cu^2+ coating can adhere to any material of any shape;addition ally,the operation can be realized on a large scale because of its simplicity.These merits provide a promising approach for developing stable and safe lithium metal batteries.

Constructing MOF-derived CoP-NC@MXene sandwich-like composite by in-situ intercalation for enhanced lithium and sodium storage

The development of dual-function anode materials for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs)is exceedingly essential.Herein,with rationally designed hierarchical metal-organic framework(MOF)@MXene as a precursor,a novel sandwich-like CoP-NC@Ti_(3)C_(2)T_(x) composite has been successfully fabricated by the following phosphorization reaction.As anode material for LIBs,the CoPNC@Ti_(3)C_(2)T_(x) composite exhibits remarkable electrochemical performance with high-rate capability(147.8 mAh g^(-1) at 2000 mA g^(-1);245.6 mAh g^(-1) at 100 mA g^(-1))and ultralong cycling life(2000 cycles with a capacity retention over 100%).For SIBs,it delivers a discharge capacity of 101.6 mAh g^(-1) at a current density of 500 mA g^(-1) after 500 cycles.The well-designed sandwich-like composite effectively supports the easy access to electrolyte,facilitate the Li/Na ion transportation,and protect the active material from pulverization upon long cycling.In addition,the electrochemical reaction kinetics and Li-migration kinetics of the CoP-NC@Ti_(3)C_(2)T_(x) composite have been pioneeringly illuminated by pseudocapacitive behavior calculation and density functional theory(DFT)computations,respectively.This work sheds light on the rational design and development of MOF/MXene-derived dual-function anode materials for Li/Na-storage.

Critical rate capability barrier by the(001)microtexture of a singlecrystal cathode for long lifetime lithium-ion batteries

In practical pouch cell,LiNi0.5Mn0.3Co0.2O2/artificial graphite lithium ion battery using single-crystal LiNi0.5Mn0.3Co0.2O2(S-NMC532)as cathode can have excellent cycle performance.However,singlecrystal LiNi0.5Mn0.3Co0.2O2 inevitably suffers poor rate capability compared to the polycrystalline materials.Here,we systematically studied the relationship between microstructural characteristics and the practical rate performance,as well as explored the impedance change during the cycling process in the pouch cell.This work shows that the(001)plane microtexture of the electrode surface structure is a critical barrier for rate capability.Electron backscatter diffraction(EBSD),electrochemical impedance spectroscopy(EIS)and distribution of relaxation times(DRT)are conducted on the cathodes.These analyses allow to conclude on the influence of the(001)plane microtexture on the electrode surface,which illustrates a diffusion resistance of lithium ions,and then,leading a high interfacial resistance.Thus,this work confirms the main cause of the inferior rate capability of S-NMC532 and offers guidance for developing a battery with high rate and ultralong cycling life.