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Anion-intercalation lithium metal batteries (AILMBs) are appealing due to their low cost and fast intercalation/de-intercalation kinetics of graphite cathodes. However, the safety and cycliability of existing AILMBs are constrained by the scarcity of compatible electrolytes. Herein, we showcase that a difluoroester can be applied as electrolyte solvent to realize high-performance AILMBs, which not only endows high oxidation resistance, but also efficiently tunes the solvation shell to enable highly reversible and kinetically fast cathode reaction beyond the trifluoro counterpart. The difluoroester-based electrolyte demonstrates nonflammability, high ionic conductivity, and electrochemical stability, along with excellent electrode compatibility. The Li| |graphite AILMBs reach a high durability of 10000 cycles with only a 0.00128% capacity loss per cycle under fast-cycling of 1 A g−1, and retain ~63% of room-temperature capacity when discharging at −65 °C, meanwhile supply stable power output under deformation and overcharge conditions. The electrolyte design paves a promising path toward fast-rate, low-temperature, durable, and safe AILMBs. The authors report a difluoroester electrolyte to enhance anion intercalation lithium metal batteries (AILMBs), improving safety and cyclability. This enables cost-effective graphitic carbon cathodes, with high durability, stability, and performance. [ABSTRACT FROM AUTHOR]

Vanadate materials are feasible cathodes for metal–ion batteries due to their stable layered structure, abundant valence states, and high capacity. However, much uncertainty still exists about precisely modulating intercalants to facilitate ion storage. Here, V2O5 pre‐intercalated with various transition metal ions M2+ (M═Ni, Co, Mn) are developed as model materials to analyze the coupling effect between guest ions and host material. Through density functional theory simulations, it is found that M2+ interacts with V–O chain via M 3d‐O 2p covalent bonds, and extended X‐ray absorption fine structure reveals the Ni─O interatomic distance at 1.56 Å shorter than Co─O (1.60 Å) and Mn─O (1.72 Å), suggesting the M–O band type with different covalency degree can optimize VOx polyhedron and local electronic structure. Furthermore, NiVO cathode materials with the smallest layer spacing shows higher redox voltage and better rate/cycling performance for Ca2+ storage than CoVO/MnVO, elucidating that Ni has stronger tendency to attract electrons and bonds with V–O layer tightly, thus supplying a reliable ion diffusion channel for Ca2+. Through ions pre‐intercalated techniques, this work highlights both layer spacing and physicochemical properties of intercalants affect electrochemical process, which is significant for developing high‐performance vanadate cathode materials. [ABSTRACT FROM AUTHOR]

Nickel‐rich LiNi1−x−yCoxMnyO2 (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 LiNi0.84Co0.07Mn0.09O2 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. [ABSTRACT FROM AUTHOR]

Air‐stable layered structured cathodes with high voltage and good cycling stability are highly desired for the practical application of Na‐ion batteries. Herein, we report a P2‐Na2/3Ni2/3Te1/3O2 cathode that is stable in ambient air with an average operating voltage of ~3.8 V, demonstrating excellent cycling stability with a capacity retention of more than 92.7% after 500 cycles at 20 mA g−1 and good rate capability with 91.9% capacity utilization at 500 mA g−1 with respect to capacity at 5 mA g−1 between 2.0 and 4.0 V. When the upper cutoff voltage is increased to 4.4 V, P2‐Na2/3Ni2/3Te1/3O2 delivers a reversible capacity of 71.9 mAh g−1 and retains 91.8% of the capacity after 100 cycles at 20 mA g−1. The charge compensation during charge/discharge is mainly due to the redox couple of Ni2+/Ni3+ in the host with a small amount of contribution from oxygen. The stable structure of the material without phase transformation and with small volume change during charge‐discharge allows it to give excellent cycle performance especially when the upper cutoff voltage is not higher than 4.2 V. [ABSTRACT FROM AUTHOR]

High‐energy lithium‐ion batteries (LIBs) can be realized with the use of nickel‐rich materials, however, their reversible operation requires long‐term cathode‐electrolyte interfacial (CEI) stability, especially for high‐temperature applications, but how the CEIs evolves during operation is still a mystery. The unstable CEIs have been recently ascribed to them generating/disappearing/regenerating during Li+ extraction/insertion by in situ Fourier Transform Infrared Spectroscopy spectrum. Herein, a strategy of insoluble CEI is proposed toward addressing the interfacially induced deterioration of cathodes with a focus on Ni‐rich layered oxides. Incorporating unsaturated units (CC/CC) to siloxane as electrolyte additives advances the commercial LiNi0.8Co0.1Mn0.1O2/graphite cells up to around 300 cycles at 60 °C with more than 85% capacity retention, along with the LiCoO2 cells reaching ≈90% capacity retention over 350 cycles under 80 °C. The experimentally and theoretically detailed investigation shows that the higher unsaturation bond with high reactive sites show more polymerization via a 3D topological pathway to form insoluble CEI species, leading to suppression of parasitic reactions, corrosive acid, transition‐metal dissolution, stress corrosive cracking, and impedance growth. The scientific discoveries of this study highlight the pivotal role of electrode–electrolyte interactions and recapitulates the tried‐and‐true "electrolyte" approach for the future development of high‐energy batteries under extreme temperature conditions. [ABSTRACT FROM AUTHOR]

Rechargeable sodium metal batteries (SMBs) have emerged as promising alternatives to commercial Li‐ion batteries because of the natural abundance and low cost of sodium resources. However, the overuse of metallic sodium in conventional SMBs limits their energy densities and leads to severe safety concerns. Herein, we propose a sodium‐free‐anode SMB (SFA‐SMB) configuration consisting of a sodium‐rich Na superionic conductor‐structured cathode and a bare Al/C current collector to address the above challenges. Sodiated Na3V2(PO4)3 in the form of Na5V2(PO4)3 was investigated as a cathode to provide a stable and controllable sodium source in the SFA‐SMB. It provides not only remarkable Coulombic efficiencies of Na plating/stripping cycles but also a highly reversible three‐electron redox reaction within 1.0–3.8 V versus Na/Na+ confirmed by structural/electrochemical measurements. Consequently, an ultrahigh energy density of 400 Wh kg−1 was achieved for the SFA‐SMB with fast Na storage kinetics and impressive capacity retention of 93% after 130 cycles. A narrowed voltage window (3.0–3.8 V vs. Na/Na+) further increased the lifespan to over 300 cycles with a high retained specific energy of 320 Wh kg−1. Therefore, the proposed SFA‐SMB configuration opens a new avenue for fabricating next‐generation batteries with high energy densities and long lifetimes. [ABSTRACT FROM AUTHOR]

All‐solid‐state batteries with conversion‐type cathodes promise to exceed the performance of lithium‐ion batteries due to their high theoretical specific energy and potential safety. However, the reported performance of solid‐state batteries is still unsatisfactory due to poor electronic and ionic conduction in the composite cathodes. Here, in situ formation of active material as well as highly effective ion‐ and electron‐conducting paths via electrochemical decomposition of Li6PS5Cl0.5Br0.5 (LPSCB)/multiwalled carbon nanotube mixtures during cycling is reported. Effectively, the LPSCB electrolyte forms a multiphase conversion‐type cathode by partial decomposition during the first discharge. Comprehensive characterization, especially operando pressure monitoring, reveals a co‐redox process of two redox‐active elements during cycling. The monolithic LPSCB‐based cell shows stable cycling over 1000 cycles with a very high capacity retention of 94% at high current density (0.885 mA cm−2, ≈0.7 C) at room temperature and a high areal capacity of 12.56 mAh cm−2 is achieved. [ABSTRACT FROM AUTHOR]

Dendrite‐induced short circuit and capacity loss present major barriers to high‐energy‐density lithium (Li) metal batteries. Many approaches have been proposed to regulate or restrain the formation of Li dendrite, yet it has not been fully eliminated. Herein, a dredging tactic with hemisphere‐like concaves is designed to horizontally release the stress during Li deposition, making both upper smooth Li and nether granular Li dwell inside the compartmented tummy. With such protuberance‐free Li metal anode, an ultrahigh Coulombic efficiency over 96% of the half‐cell is maintained after 490 cycles and capacity retention of 100% for the full cell paired with a LiFePO4 cathode after 140 cycles (with low N/P ratio of ≈5) is achieved simultaneously. This study contributes to a deeper comprehension of electrochemical metal deposition and promotes the development of safe batteries. [ABSTRACT FROM AUTHOR]

Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode candidate for the next‐generation high energy‐density lithium‐ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site‐selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fd3‾ m structure. This site‐selective doping not only suppresses unfavorable two‐phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg‐doped LNMOs exhibit extraordinarily stable electrochemical performance in both half‐cells and prototype full‐batteries with novel TiNb2O7 counter‐electrodes. This work pioneers an atomic‐doping engineering strategy for electrode materials that could be extended to other energy materials to create high‐performance devices. [ABSTRACT FROM AUTHOR]

A facile, low-cost precipitation method, utilizing an autogenously protective atmosphere without the assistance of an inert atmosphere, is proposed to synthesize nano-sized Prussian white K1.62Fe[Fe(CN)6]0.92·0.33H2O. The cathode delivers a high capacity of 120.9 mA h g−1 at 50 mA g−1 and an ultrahigh capacity retention of 98.2% after 100 cycles. [ABSTRACT FROM AUTHOR]

Rechargeable lithium-air (Li-O2) batteries have drawn much interest owing to their high energy density. We report on the effect of deliberately introducing potassium impurities into the cathode material on the electrochemical performance of a Li-O2 battery. Small amounts of potassium introduced into the activated carbon (AC) cathode material in the synthesis process are found to have a dramatic effect on the performance of the Li-O2 cell. An increased amount of potassium significantly increases capacity, cycle life, and round-trip efficiency. This improved performance is probably due to a larger amount of LiO2 in the discharge product, which is a mixture of LiO2 and Li2O2, resulting from the increase in the amount of potassium present. No substantial correlation with porosity or surface area in an AC cathode is found. Experimental and computational studies indicate that potassium can act as an oxygen reduction catalyst, which can account for the dependence of performance on the amount of potassium. [ABSTRACT FROM AUTHOR]

Lithium iron phosphate/carbon (LiFePO4/C) microspheres with high rate and cycling performance are synthesized from iron phosphate/polyacrylic acid (FePO4/PAA) nanoparticles. Iron(III) acrylate is used as a precursor for both the iron and carbon sources. FePO4 nanoparticles are first produced by a coprecipitation reaction. The byproduct, acrylic acid ions, is polymerized in situ to form a uniform PAA layer on the surface of the FePO4 nanoparticles. The as-prepared LiFePO4/C microspheres are composed of primary nanoparticles with sizes of 40-50 nm. The nanoparticles are fully coated with a thin, uniform carbon layer derived from the decomposition of the PAA layer. The uniform carbon-coating layer cooperates with interstitial and boundary carbon derived from sucrose successfully to construct an excellent interconnecting conductive network in the microspheres. As a result of the unique structure, the as-prepared LiFePO4/C microspheres display both high electronic and ionic conductivities, which contribute to their high rate performance (162.9 mAh g−1 at 0.1C and 126.1 mAh g−1 at 5C) and excellent cycling stability (97.1 % of capacity retention after 500 cycles at 5C/5C). [ABSTRACT FROM AUTHOR]

Abstract: LiFePO4/C and V-doped LiFePO4/C with VO2(B) coating composite were prepared by an inorganic-based sol–gel method and the related properties were compared. The V-doping and VO2(B) coating was verified by high-resolution transmission electron microscopy and energy-dispersive X-ray spectrometry. The formation mechanism of the VO2(B) coating was deduced. The XPS analysis suggested that the valence state of V was +4. The coupling effects of the V-doping and VO2(B) coating on the electric conductivity, lithium-ion diffusion velocity and discharge specific capacities at various C-rates were investigated. It is found that the V-doping and VO2(B) coating result in the increase of the bulk electric conductivity, the improvement of the kinetics and the enhancement of the rate capability. Moreover, the cyclic stability was not influenced significantly, even at 10C. [Copyright &y& Elsevier]

Nanocrystalline LiFePO and LiFeSnPO cathode materials were synthesized by an inorganic-based sol-gel route. The physicochemical properties of samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and elemental mapping. The doping effect of Sn on the electrochemical performance of LiFePO cathode material was extensively investigated. The results showed that the doping of tin was beneficial to refine the particle size, increase the electrical conductivity, and facilitate the lithium-ion diffusion, which contributed to the improvement of the electrochemical properties of LiFePO, especially the high-rate charge/discharge performance. At the low discharge rate of 0.5 C, the LiFeSnPO sample delivered a specific capacity of 158 mAh g, as compared with 147 mAh g of the pristine LiFePO. At higher C-rate, the doping sample exhibited more excellent discharge performance. LiFeSnPO delivered specific capacity of 146 and 128 mAh g at 5 C and 10 C, respectively, in comparison with 119 and 107 mAh g for LiFePO. Moreover, the doping of Sn did not influence the cycle capability, even at 10 C. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline LiFe1−x Sn x PO4 (0≤ x ≤0.07) samples are synthesized using SnCl4·5H2O as dopant via an inorganic-based sol–gel method. The dependency of the physicochemical and electrochemical properties on the doping amount of tin are systemically worked out and regular changes are revealed. In the whole concentration range, the chemical valence of Fe2+ is not basically changed whereas tin is found in two different oxidation states, namely +2 and +4. The replacement of Fe2+ by supervalent Sn4+ would lead to electron compensation. Under the synergetic effects between the charge compensation and the crystal distortion, the electrical conductivities for the bulk samples first increase and then decrease with the increasing amount of Sn doping. Upon the doping amount, the apparent lithium-ion diffusion coefficient and the electrochemical performance also display the similar trends. The doping is beneficial to refine the particle size and narrow down the size distribution, however optimizing the doping amount is necessary. Compared with other samples, the sample with a doping amount of about 3mol% delivers the highest capacities at all C-rates and exhibits the excellent rate capability due to the high electrical conductivity and the fast lithium-ion diffusion velocity. [Copyright &y& Elsevier]

Graphite nanofibers (GNFs), on which surface graphite edges were reconstructed into nano-loops, were explored as a cathode catalyst support for fuel cells. The high degree of graphitization, as well as the surface-reconstructed nano-loops that possess topological defects for uniform metal deposition, resulted in an improved performance of the GNF-supported Pt catalyst. [ABSTRACT FROM AUTHOR]

Uncontrollable dendrite growth and poor reversibility of lithium (Li) metal anode hinder the practical implementation of Li metal based batteries. Herein, we report a feasible and scalable electrospraying strategy for fabricating a vertically aligned graphene (VAG) pillar architecture with low tortuosity and high specific surface area as both current collector and host material for Li metal anode. Columnar and dense Li with large granular size plates into the VAG electrode by the aid of the pillar structure, which could ensure continuous ion transfer and lower actual current density for uniform nucleation, as well as provide more accommodation with proper space size. The hollow graphene pillars and the surrounding sufficient space enables smooth Li plating under high capacity depth and abstains volume fluctuation of the whole electrode. The VAG pillar modified Li anode delivers low overpotential of 25 mV over 280 h under a high rate of 3 mA cm−2, and high Coulombic efficiencies for 250 cycles at a capacity of 1 mAh cm−2. More importantly, full cells paired with the high capacity LiFePO 4 cathode exhibit excellent cycling stability and rate capability, demonstrating the high Li utilization efficiency and improved ion migration kinetic in the low tortuous VAG architecture. A lightweight vertically aligned graphene (VAG) architecture consisting of open channels and vertical graphene pillars is developed by a facile and scalable method. The low tortuosity, large specific surface area of VAG architecture contribute to dendrite-free Li plating behavior and continuous ion-transport pathways, thus significantly enhancing the reversibility of anode. [Display omitted] • A vertically aligned graphene (VAG) architecture with low tortuosity is developed. • The VAG architecture consists of hollow graphene pillar and appropriate interspace. • Uniform and columnar Li deposits are realized into internal space of VAG electrode. • The reversibility of VAG-modified anode is thus significantly improved. [ABSTRACT FROM AUTHOR]

Metallic Na possesses high specific capacity and lowest electrochemical potential of all possible candidates, and therefore being regarded as one of the most promising anode materials for Na batteries. Nevertheless, unstable solid electrolyte interface, infinite volume change and uncontrollable dendritic Na growth upon repeated Na plating/stripping processes lead to low Coulombic efficiency, poor cyclability and safety concerns of Na metal anode. Herein, a three-dimensional carbon felt host was employed to suppress Na dendrite growth, thus achieving highly reversible Na plating/stripping process. The interstitial space inside the carbon felt framework accommodates Na deposition, and the plentiful active sites guide homogenous Na nucleation and growth without dendrite formation. As a result, the carbon felt exhibits stable cycling lifetime for 1100 h and 350 h at 1 mA cm−2 and 2 mA cm−2 respectively, which are 5.6 and 3.9 times longer than that of Al foil. Moreover, the carbon felt possesses high average Coulombic efficiency of ∼99.3% for 500 cycles at 0.5 mA cm−2. When paired with Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode, the full cell delivers a high capacity retention of 95.1% over 150 cycles. Image 1 [ABSTRACT FROM AUTHOR]

In this study, highly crystalline FeFe(CN) 6 with metal-organic framework is synthesized and measured in NaNO 3 and LiNO 3 . Electrochemical kinetics, physical and chemical changes about the insertion and extraction processes of sodium ions and lithium ions in FeFe(CN) 6 are compared and discussed. Intriguingly, it exhibits a good electrochemical performance in sodium aqueous batteries, with a capacity of 118 mAh g −1 at 400 mA g −1 , but a poor electrochemical behavior in lithium aqueous batteries. This study sheds light on the different insertion processes between sodium ions and lithium ions in FeFe(CN) 6 , that the outer petaloid-like structure forms on the surface of FeFe(CN) 6 after Li ions insertion with little volume expansion, while FeFe(CN) 6 after Na ions insertion could still maintain the cubic-like structure with lattice change. Different insertion mechanisms of sodium ions and lithium ions are proposed that hydrated Na ions could insert at interstitial sites, while hydrated Li ions are more likely to occupy large open sites due to the larger radius of hydrated Li ions than hydrated Na ions. Besides, insertion/extraction performance and capacitive preformance dominate in NaNO 3 and LiNO 3 , respectively. These differences may lead to the different electrochemical behaviors between sodium-ion and lithium-ion aqueous batteries. [ABSTRACT FROM AUTHOR]

During the cycling of Li-O2batteries thedischarge process gives rise to dynamically evolving agglomeratescomposed of lithium–oxygen nanostructures; however, littleis known about their composition. In this paper, we present resultsfor a Li-O2battery based on an activated carbon cathodethat indicate interfacial effects can suppress disproportionationof a LiO2component in the discharge product. High-intensityX-ray diffraction and transmission electron microscopy measurementsare first used to show that there is a LiO2component alongwith Li2O2in the discharge product. The stabilityof the discharge product was then probed by investigating the dependenceof the charge potential and Raman intensity of the superoxide peakwith time. The results indicate that the LiO2componentcan be stable for possibly up to days when an electrolyte is lefton the surface of the discharged cathode. Density functional calculationson amorphous LiO2reveal that the disproportionation processwill be slower at an electrolyte/LiO2interface comparedto a vacuum/LiO2interface. The combined experimental andtheoretical results provide new insight into how interfacial effectscan stabilize LiO2and suggest that these interfacial effectsmay play an important role in the charge and discharge chemistriesof a Li–O2battery. [ABSTRACT FROM AUTHOR]

Abstract: The structural and thermal stabilities of the layered Li(Ni1/3Co1/3Mn1/3)O2 cathode materials under high rate cycling and abusive conditions are investigated using the commercial 18650 Li(Ni1/3Co1/3Mn1/3)O2/graphite high power batteries. The Li(Ni1/3Co1/3Mn1/3)O2 materials maintain their layered structure even when the power batteries are subjected to 200 cycles with 10C discharge rate at temperatures of 25 and 50°C, whereas their microstructure undergoes obvious distortion, which leads to the relatively poor cycling performance of power batteries at high charge/discharge rates and working temperature. Under abusive conditions, the increase in the battery temperature during overcharge is attributed to both the reactions of electrolyte solvents with overcharged graphite anode and Li(Ni1/3Co1/3Mn1/3)O2 cathode and the Joule heat that results from the great increase in the total resistance (R cell) of batteries. The reactions of fully charged Li(Ni1/3Co1/3Mn1/3)O2 cathodes and graphite anodes with electrolyte cannot be activated during short current test in the fully charged batteries. However, these reactions occur at around 140°C in the fully charged batteries during oven test, which is much lower than the temperature of about 240°C required for the reactions outside batteries. [Copyright &y& Elsevier]

LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) is widely used as cathode material in commercialized high energy density lithium ion battery due to its high specific capacity. However, the structure and thermal stability of NCA after long electrochemical cycles are remained unclear. Herein, we investigate the structure and thermal stability of aged NCA at both lithiated and delithiated states using in-situ charge/discharge and high temperature X-ray diffraction and transmission electron microscopy images. The thermal stability of delithiated NCA cathode after 400 cycles at 1C is obviously inferior to the lithiated and pristine one. The particle surface of aged NCA changes from layered to spinel phase, while the bulk area maintains the layered structure. The temperature inducing structure change of aged NCA is much lower than that of pristine NCA and the delithiated state of NCA is more vulnerable at high temperature. The drastic structure transformation of aged NCA occurs at 250 °C during heating, which accompanies with oxygen loss and the formation of intergranular cracks in the NCA secondary particles. Thus, this work provides significant information of structure stability of cycled NCA at high temperature for optimizing its surface structure to achieve excellent cycling performance under extreme conditions. • Thermal stability of delithiated cycled LiNi 0.8 Co 0.15 Al 0.05 O 2 is obviously inferior. • Particle surface of aged LiNi 0.8 Co 0.15 Al 0.05 O 2 changes from layered to spinel phase. • Bulk area of aged LiNi 0.8 Co 0.15 Al 0.05 O 2 maintains the layer structure. • Drastic structure transformation of aged LiNi 0.8 Co 0.15 Al 0.05 O 2 occurs at 250 °C. [ABSTRACT FROM AUTHOR]