New insights into the pre-lithiation kinetics of single-crystalline Ni-rich cathodes for long-life Li-ion batteries

Developing single-crystalline Ni-rich cathodes is an effective strategy to improve the safety and cycle life of Li-ion batteries(LIBs).However,the easy-to-loss of Li and O in high-temperature lithiation results in unsatisfactory ordered layered structure and stoichiometry.Herein,we demonstrate the synthesis of highly-ordered and fully-stoichiometric single-crystalline LiNi_(0.83)Co_(0.12)Mn_(0.05)O_(2)(SC-NCM83)cathodes by the regulation of pre-lithiation kinetics.The well-balanced pre-lithiation kinetics have been proved to greatly improve the proportion of layered phase in the intermediate by inhibiting the formation of metastable spinel phase,which promoted the rapid transformation of the intermediate into highly-ordered layered SC-NCM83 in the subsequent lithiation process.After coating a layer of Li_(2)O–B_(2)O_(3),the resultant cathodes deliver superior cycling stability with 90.9%capacity retention at 1C after 300 cycles in pouch-type full batteries.The enhancement mechanism has also been clarified.These findings exhibit fundamental insights into the pre-lithiation kinetics process for guiding the synthesis of high-quality singlecrystalline Ni-rich cathodes.

Revealing the key role of non-solvating diluents for fast-charging and low temperature Li-ion batteries

Fast-charging and low temperature operation are of vital importance for the further development of lithium-ion batteries(LIBs),which is hindered by the utilization of conventional carbonate-based electrolytes due to their slow kinetics,narrow operating temperature and voltage range.Herein,an acetonitrile(AN)-based localized high-concentration electrolyte(LHCE)is proposed to retain liquid state and high ionic conductivity at ultra-low temperatures while possessing high oxidation stability.We originally reveal the excellent thermal shielding effect of non-solvating diluent to prevent the aggregation of Li^(+) solvates as temperature drops,maintaining the merits of fast Li transport and facile desolvation as at room temperature,which bestows the graphite electrode with remarkable low temperature performance(264 mA h g^(-1) at-20 C).Remarkably,an extremely high capacity retention of 97%is achieved for high-voltage high-energy graphite||NCM batteries after 250 cycles at-20 C,and a high capacity of 110 mA h g^(-1)(71%of its room-temperature capacity)is retained at-30°C.The study unveils the key role of the non-solvating diluents and provides instructive guidance in designing electrolytes towards fast-charging and low temperature LIBs.

A high Li-ion diffusion kinetics in multidimensional and compact-structured electrodes via vacuum filtration casting

Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant challenge.In this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration approach.Both as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell configuration.The assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),respectively.The excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion kinetics.Furthermore,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.

Synthesizing core-shell Ni-rich LiNi_(x)Co_(y)Mn_(z)O_(2) from spent Li-ion battery leachate

As the global electric vehicle market continues to grow,the recycling of Li-ion battery (LIB) becomes more important worldwide and the resynthesis of cathode materials would be the most value-added recycling approach taking into account limited metal resources.Although resynthesized homogenous LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM) from spent LIB leachate shows comparable battery performance to pristine NCM from virgin materials,there is general concern in its cycling performance.Here,we synthesize core–shell(CS) Ni-rich NCM,which consists of Ni-rich NCM as the core and NCM derived from the original or purified leachate of spent LIBs as the shell.Resynthesized CS Ni-rich NCM exhibits improved rate capability resulting from expanded interslab thickness in the NCM structure.CS Ni-rich NCM from purified LIB leachate shows improvement in cycling performance and thermal stability.It specifically delivers a capacity retention of 86.6%at a high temperature after 80 cycles compared to that (75.0%) of pristine CS Ni-rich NCM.These improvements are caused by a relatively high Mg content on the shell and the widespread distribution of Al through the CS structure.CS Ni-rich NCM derived from spent LIB leachate provides a new alternative approach to conventional LIB recycling methods,which would utilize efficiently limited metal resources for the sustainable LIB production.

A comprehensive review on the resynthesis of ternary cathode active materials from the leachate of Li-ion batteries

This review highlights the importance of recovering valuable metals from spent Li-ion battery(LIB)cathodes through the resynthesis of cathode active materials(CAMs).The resynthesis process of CAMs,a promising recycling method that directly produces CAM precursors from LIB leachate,is explored.This process encompasses six key steps,including pretreatment,leaching,purification,adjustment of metal concentrations,precursor synthesis,and sintering.The review also investigates the potential introduction of impurity elements during CAM resynthesis and provides tolerance levels for these impurities based on thorough reference analysis.Additionally,it addresses challenges related to the commercialization of the resynthesis process.Notably,this review represents the first comprehensive assessment of CAM resynthesis,including the systematic evaluation of 12 impurity elements(Fe,Li,Al,Cu,C,P,F,Na,Cl,S,Mg,and Zn).Overall,this comprehensive review is poised to support the commercial development of resynthesized CAMs by offering valuable guidelines for managing impurities and streamlining the purification process.

Interface-reinforced solid-state electrochromic Li-ion batteries enabled by in-situ liquid-solid transitional plastic glues

The electrochromic Li-ion batteries(ELIBs) combine the functions of electrochromism and energy storage,realizing the display of energy-storage levels by visual signals. However, the accompanying interfacial issues including physical contact and(electro)chemical stability should be taken into account when the conventional liquid/gel electrolytes are replaced with solid-state counterparts. Herein, the in-situ liquid-solid transitional succinonitrile(SCN) plastic glues are constructed between electrodes and poly(ethylene oxide)(PEO) polymer electrolytes, enabling an interface-reinforced solid-state ELIB.Specifically, the liquid SCN precursor can adequately wet electrode/PEO interfaces at high temperature,while it returns back to solid state at room temperature, leading to seamless interfacial contact and smooth ionic transfer without changing the solid state of the device. Moreover, the SCN interlayer suppresses the direct contact of PEO with electrodes containing high-valence metal ions, evoking the improved interfacial stability by inhibiting the oxidation of PEO. Therefore, the resultant solid-state ELIB with configuration of LiMn_(2)O_(4)/SCN-PEO-SCN/WO_(3) delivers an initial discharge capacity of 111 m A h g^(-1) along with a capacity retention of 88.3% after 200 cycles at 30 ℃. Meanwhile, the electrochromic function is integrated into the device by distinguishing its energy-storage levels through distinct color changes. This work proposes a promising solid-state ELIB with greatly reinforced interfacial compatibility by introducing in-situ solidified plastic glues.

Atomistic understanding of capacity loss in LiNiO_(2)for high-nickel Li-ion batteries:First-principles study

Combining the first-principles calculations and structural enumeration with recognition,the delithiation process of LiNiO_(2)is investigated,where various supercell shapes are considered in order to obtain the formation energy of Li_(x)NiO_(2).Meanwhile,the voltage profile is simulated and the ordered phases of lithium vacancies corresponding to concentrations of 1/4,2/5,3/7,1/2,2/3,3/4,5/6,and 6/7 are predicted.To understand the capacity decay in the experiment during the charge/discharge cycles,deoxygenation and Li/Ni antisite defects are calculated,revealing that the chains of oxygen vacancies will be energetically preferrable.It can be inferred that in the absence of oxygen atom in high delithiate state,the diffusion of Ni atoms is facilitated and the formation of Li/Ni antisite is induced.

Two-dimensional MOF-based materials:Preparations and applications as electrodes in Li-ion batteries

Two-dimensional(2D)metal-organic frameworks(MOFs)are rapidly emerging as a unique class of mushrooming family of 2D materials offering distinctive features,such as hierarchical porosity,extensive surface area,easily available active sites,and versatile,adaptable structures.These promising characteristics have positioned them as highly appealing alternatives for a wide range of applications in energy storage technologies,including lithium batteries.Nevertheless,the poor conductivity and limited stability of 2D MOFs have limited their real applications in electrochemical energy storage.These limitations have therefore warranted ongoing research to enhance the performance of 2D MOFs.Given the significance of 2D MOF-based materials as an emerging class of advanced materials,a multitude of strategy has been devised to address these challenges such as synthesizing 2D conductive MOFs and derivatives along with 2D MOF hybridization.One promising approach involves the use of 2D MOF derivatives,including transition metal oxides,which due to their abundant unsatu rated active metal sites and shorter diffusion paths,offer superior electrochemical performance.Additionally,by combining pristine 2D MOFs with other materials,hybrid 2D MOF materials can be created.These hybrids,with their enhanced stability and conductivity,can be directly utilized as active materials in lithium batteries.In the present review,we categorize 2D MOF-based materials into three distinct groups:pristine 2D MOFs,2D MOFderived materials,and 2D MOF hybrid materials.The synthesis methods for each group,along with their specific applications as electrode materials in lithium-ion batteries,are discussed in detail.This comprehensive review provides insights into the potential of 2D MOFs while highlighting the opportunities and challenges that are present in this evolving field.

Li-Ion Transport Mechanisms in Selenide-Based Solid-State Electrolytes in Lithium-Metal Batteries:A Study of Li_(8)SeN_(2),Li_(7)PSe_(6),and Li_(6)PSe_(5)X(X=Cl,Br,I)

To achieve high-energy-density and safe lithium-metal batteries(LMBs),solid-state electrolytes(SSEs)that exhibit fast Li-ion conductivity and good stability against lithium metal are of great importance.This study presents a systematic exploration of selenide-based materials as potential SSE candidates.Initially,Li_(8)SeN_(2)and Li_(7)PSe_(6)were selected from 25 ternary selenides based on their ability to form stable interfaces with lithium metal.Subsequently,their favorable electronic insulation and mechanical properties were verified.Furthermore,extensive theoretical investigations were conducted to elucidate the fundamental mechanisms underlying Li-ion migration in Li_(8)SeN_(2),Li_(7)PSe_(6),and derived Li_(6)PSe_(5)X(X=Cl,Br,I).Notably,the highly favorable Li-ion conduction mechanism of vacancy diffusion was identified in Li6PSe5Cl and Li_(7)PSe_(6),which exhibited remarkably low activation energies of 0.21 and 0.23 eV,and conductivity values of 3.85×10^(-2)and 2.47×10^(-2)S cm^(-1)at 300 K,respectively.In contrast,Li-ion migration in Li_(8)SeN_(2)was found to occur via a substitution mechanism with a significant diffusion energy barrier,resulting in a high activation energy and low Li-ion conductivity of 0.54 eV and 3.6×10^(-6)S cm^(-1),respectively.Throughout this study,it was found that the ab initio molecular dynamics and nudged elastic band methods are complementary in revealing the Li-ion conduction mechanisms.Utilizing both methods proved to be efficient,as relying on only one of them would be insufficient.The discoveries made and methodology presented in this work lay a solid foundation and provide valuable insights for future research on SSEs for LMBs.

Enhanced Li storage of pure crystalline-C_(60) and TiNb_(2)O_(7)-nanostructure composite for Li-ion battery anodes

We propose a method for producing composite materials(hTNO@C_(60))comprising crystalline C_(60)particles and hollow-structu red TiNb_(2)O_(7)(hTNO)nanofibers via facile liquid-liquid interface precipitation followed by low-temperature annealing.This allows the systematic design of crystalline C_(60)as an active material for Li-ion battery anodes.The hTNO@C_(60)composite demonstrates outstanding cyclic stability,retaining a capacity of 465 mA h g^(-1)after 1,000 cycles at 1 A g^(-1)It maintains a capacity of 98 mA h g^(-1)even after16,000 ultralong cycles at 8 A g^(-1)The enhancement in electrochemical properties is attributed to the successful growth and uniform doping of crystalline C_(60),resulting in improved electrical conductivity.The excellent electrochemical stability and properties of these composites make them promising anode materials.

Effect of Heatpipe Array Condenser Section Length on Thermal Cooling of Li-Ion Batteries

One of the new methods for ensuring that the battery in a thermal energy storage system is kept at the proper temperature is the heat pipe-based ThermalManagement System(TMS).In this study,the improvement of cooling performance of a heat pipe based TMS is examined through the variation of condenser section length of heat pipes in an array.The TMSs with an array of heat pipes with different condenser section lengths are considered.The system performances are evaluated using a validated numerical method.The results show that a heat pipebased TMS provides the best cooling performance when a wavy-like variation is employed and when the condenser section length of the last set of the heat pipe in the array is greater than that of the penultimate set.The maximum cell temperature and the maximum temperature difference within the cell of this TMS are decreased by 4.2 K and 1.1 K,respectively,when compared to the typical heat pipe based TMS with zero variation in its condenser section length.Conclusively,the strategy offers an improvement in the thermal uniformity for all the TMS cases.

Chip Design of Li-Ion Battery Charger Operating in Constant-Current/Constant-Voltage Modes

A design for a Li-ion battery charger IC that can operate in a constant current-constant voltage （CC- CV） charge mode is proposed. In the CC-CV charge mode,the charger IC provides a constant charging current at the beginning, and then the charging current begins to decrease before the battery voltage reaches its final value. After the battery voltage reaches its final value and remains constant,the charging current is further reduced. This approach prevents charging the battery with full current near its saturated voltage,which can cause heating. The novel design of the core of the charger IC realizes the proposed CC-CV charge mode. The chip was implemented in a CSMC 0.6μm CMOS mixed signal process. The experimental results verify the realization of the proposed CC- CV charge mode. The voltage of the battery after charging is 4. 1833V.

Physics of electron and lithium-ion transport in electrode materials for Li-ion batteries

The physics of ionic and electrical conduction at electrode materials of lithium-ion batteries （LIBs） are briefly sum marized here, besides, we review the current research on ionic and electrical conduction in electrode material incorporating experimental and simulation studies. Commercial LIBs have been widely used in portable electronic devices and are now developed for large-scale applications in hybrid electric vehicles （HEV） and stationary distributed power stations. However, due to the physical limits of the materials, the overall performance of today＇s LIBs does not meet all the requirements for future applications, and the transport problem has been one of the main barriers to further improvement. The electron and Li-ion transport behaviors are important in determining the rate capacity of LIBs.

Research on cathode material of Li-ion battery by yttrium doping

Modification of LiFePO4, LiMn2O4 and Li1＋xV3O8 by doping yttrium was investigated. The influences of doping Y on structure, morphology and electrochemical performance of cathode materials were investigated systematically. The results indicated that the mechanisms of Y doping in three cathode materials were different, so the influences on the material performance were different. The crystal structure of the three materials was not changed by Y doping. However, the crystal parameters were influenced. The crystal parameters of LiMn2O4 became smaller, and the interlayer distance of （100） crystal plane of Li1-xV3O8 was lengthened after Y doping. The grain size of Y-doped LiFePO4 became smaller and grain morphology became more regular than that of undoped LiFePO4. It indicated that Y doping had no influence on crystal particle and morphology of LiMn2O4. The morphology of Li1＋xV3O8 became irregular and its size became larger with the increase of Y. For LiFePOaand Li1＋xV3O8, both the initial discharge capacities and the cyclic performance were improved by Y doping. For LiMn2O4, the cyclic performance became better and the initial discharge capacities declined with increasing Y doping.

Si-Based Anode Materials for Li-Ion Batteries:A Mini Review

Si has been considered as one of the most attractive anode materials for Li-ion batteries(LIBs) because of its high gravimetric and volumetric capacity. Importantly, it is also abundant, cheap, and environmentally benign. In this review, we summarized the recent progress in developments of Si anode materials. First, the electrochemical reaction and failure are outlined, and then, we summarized various methods for improving the battery performance, including those of nanostructuring, alloying, forming hierarchic structures, and using suitable binders. We hope that this review can be of benefit to more intensive investigation of Si-based anode materials.

Electrochemical performance of carbon nanotube-modified LiFePO_4 cathodes for Li-ion batteries

Carbon nanotubes (CNTs) and acetylene black (AB) were dispersed synchronously or separately between LiFePO4 (LFP) particles as conducting agents during the course of manufacture of LiFePO4 cathodes. The morphology and electrochemical performances of as-prepared LiFePO4 were evaluated by means of transmission electron microscopy (TEM), charge-discharge test, electrochemical impedance spectroscope (EIS) and cyclic voltammetry (CV). CNTs contribute to the interconnection of the isolated LiFePO4 or carbon particles. For the CNTs-modified LiFePO4, it exhibits excellent performance in terms of both specific capacity and cycle life. The initial discharge capacity is 147.9 mA·h/g at 0.2C rate and 134.2 mA·h/g at 1C rate, keeping a capacity retention ratio of 97% after 50 cycles. The results from EIS indicate that the impedance value of the solid electrolyte interface decreases. The cyclic voltammetric peak profiles is more symmetric and spiculate and there are fewer peaks. CNTs are promising conductive additives candidate for high-power Li-ion batteries.

High-Performance Li-ion Batteries and Super-capacitors Based on Prospective 1-D Nanomaterials

One-dimensional（1-D） nanomaterials with superior specific capacity, higher rate capability, better cycling peroperties have demonstrated significant advantages for high-performance Li-ion batteries and supercapacitors. This review describes some recent developments on the rechargeable electrodes by using 1-D nanomaterials（such as Li Mn2O4 nanowires, carbon nanofibers, Ni Mo O4 · n H2O nanorods, V2O5 nanoribbons,carbon nanotubes, etc.）. New preparation methods and superior electrochemical properties of the 1-D nanomaterials including carbon nanotube（CNT）, some oxides, transition metal compounds and polymers, and their composites are emphatically introduced. The VGCF/Li Fe PO4/C triaxial nanowire cathodes for Li-ion battery present a positive cycling performance without any degradation in almost theoretical capacity（160 m Ah/g）.The Si nanowire anodes for Li-ion battery show the highest known theoretical charge capacity（4277 m Ah/g）,that is about 11 times lager than that of the commercial graphite（372 m Ah/g）. The SWCNT/Ni foam electrodes for supercapacitor display small equivalent series resistance（ESR, 52 m?） and impressive high power density（20 k W/kg）. The advantages and challenges associated with the application of these materials for energy conversion and storage devices are highlighted.

Synthesis and electrochemical performances of LiCoO_2 recycled from the incisors bound of Li-ion batteries

A new LiCoO2 recovery technology for Li-ion batteries was studied in this paper. LiCoO2 was peeled from the Al foil with dimethyl acetamide （DMAC）, and then polyvinylidene fluoride （PVDF） and carbon powders in the active material were eliminated by high temperature calcining. Subsequently, Li2CO3, LiOH-H20 and LiAc-2H2O were added into the recycled powders to adjust the Li/Co molar ratio to 1.00. The new LiCoO2 was obtained by calcining the mixture at 850℃ for 12 h in air. The structure and morphology of the recycled powders and resulting samples were studied by XRD and SEM techniques, respectively. The layered structure of LiCoO2 synthesized by adding Li2CO3 is the best, and it is found to have the best characteristics as a cathode material in terms of charge-discharge capacity and cycling performance. The first discharge capacity is 160 mAh·g^-1 between 3.0-4.3 V. The discharge capacity after cycling for 50 times is still 145.2 mAh·g^-1.

TiO_2 nanocrystals/graphene hybrids with enhanced Li-ion storage performance

TiO2 nanocrystals/graphene hybrids（TiO2-G） with ultrafine TiO2 nanocrystals（7 nm in size） conformally coated on ultrathin graphene nanosheets（ 2 layers thick） were successfully prepared via a facile one-pot solvothermal route under mediated conditions.With the feature of large surface area,abundant mesopores and high thermal stability,the TiOi-G nanohybrids exhibited large reversible Li-ion storage capacity with excellent cycling stability（629 mAh·g-1 after 400 cycles at a current of 60 mA·g-1） and good rate capability（184 mAh·g-1 at a current density of 3 A·g-1） due to the synergetic effects and strong interactions between the components,showing great promise in applications for advanced energy storage devices.

Synthesis and characterization of phosphate-modified LiMn_2O_4 cathode materials for Li-ion battery

LiMn2O4 spinel cathode materials were modified with 2 wt.%Li-M-PO4（M=Co,Ni,Mn） by polyol synthesis method.The phosphate surface-modified LiMn2O4 cathode materials were physically characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and energy dispersive X-ray spectroscopy（EDS）.The charge-discharge test showed that the cycling and rate capacities of LiMn2O4 cathode materials were significantly enhanced by stabilizing the electrode surface with phosphate.