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Designing defect‐rich MoS2/C architectures with three‐dimensional (3D) porous frame effectively improve the electrochemical performance of lithium‐ion batteries (LIBs) owing to the improved conductivity and decreased diffusion distance of Li+ ions for lithium storage. Herein, we report a reliable morphology engineering method combining with tunable defects to synthesize defect‐rich MoS2 nanosheets with a few layers entrapped carbon sheath, forming a 3D porous conductive network architecture. The defect‐rich MoS2 nanosheets with expanded interlayers can provide a shortened ion diffusion path, and realize the 3D Li+ diffusion with faster kinetics. A 3D conductive interconnected carbon network is able to improve interparticle conductivity, concurrently maintaining the structural integrity. Benefiting from these intriguing features, the as‐prepared MoS2/C architectures exhibit excellent electrochemical performance: a high reversible capacity of 1163 mAh g−1 at a current density of 0.1 A g−1 after 100 cycles and a high rate capability of 800 mAh g−1 at 5 A g−1. Defect content in MoS2/C architectures can be obtained by changing H2 concentration. Compared with the counterparts with few defects, the defect‐rich MoS2/C architectures show improved electrochemical stability with a superior cycle life, illustrating a highly reversible capacity of 751 mAh g−1 at 0.5 A g−1 after 500 cycles. [ABSTRACT FROM AUTHOR]

Silicon is a promising anode material for lithium-ion and post lithium-ion batteries but suffers from a large volume change upon lithiation and delithiation. The resulting instabilities of bulk and interfacial structures severely hamper performance and obstruct practical use. Stability improvements have been achieved, although at the expense of rate capability. Herein, a protocol is developed which we describe as two-dimensional covalent encapsulation. Two-dimensional, covalently bound silicon-carbon hybrids serve as proof-of-concept of a new material design. Their high reversibility, capacity and rate capability furnish a remarkable level of integrated performances when referred to weight, volume and area. Different from existing strategies, the two-dimensional covalent binding creates a robust and efficient contact between the silicon and electrically conductive media, enabling stable and fast electron, as well as ion, transport from and to silicon. As evidenced by interfacial morphology and chemical composition, this design profoundly changes the interface between silicon and the electrolyte, securing the as-created contact to persist upon cycling. Combined with a simple, facile and scalable manufacturing process, this study opens a new avenue to stabilize silicon without sacrificing other device parameters. The results hold great promise for both further rational improvement and mass production of advanced energy storage materials. Stabilizing silicon without sacrificing other device parameters is essential for practical use in lithium and post lithium battery anodes. Here, the authors show the skin-like two-dimensional covalent encapsulation furnishing a remarkable level of integrated lithium storage performances of silicon. [ABSTRACT FROM AUTHOR]

With the demand for higher energy density and smaller size lithium-ion batteries (LIBs), the development of high specific capacity active materials and the reduction of the usage of inactive materials are the main directions. Herein, a universal method is developed for binder-free electrodes for excellent stable LIBs by rolling the electrospun membrane directly onto the commercial current collector. The rolling process only makes the fiber web denser without changing the fiber structure, and the fiber web still maintains a porous structure. This strategy significantly improves the structural stability of the membrane compared to the direct carbonized electrospun membrane. Moreover, this method is suitable for a variety of polymerizable adhesive polymers, and each polymer can be composited with different polymers, inorganic salts, etc. The electrode prepared by this method can be stably cycled for more than 2000 cycles at a current density of 2500 mA g−1. This study provides a cost-effective and versatile strategy to design the LIB electrode with high energy density and stability for experimental research and practical application. [ABSTRACT FROM AUTHOR]

The processes of lithization and delithization of a perfect and defective (containing monovacancies) silicene channel located on an Ni(111) substrate are studied in a molecular-dynamic (MD) experiment. It is shown that such a system can exist up to 1 ns in time without destruction. The limiting amount of lithium ions intercalated into the silicene channel modified by monovacancies is 20% higher than for a defect-free structure. At the same time, the silicene sheets are not destroyed and retain their integrity. The predominant observed arrangement of lithium atoms in the channel is above the centers of the hexagonal silicon rings. In the channel formed by perfect silicene, the lithium mobility coefficient is twice as high as in a defective structure. In general, nickel as a substrate for a silicene channel can be a promising material in terms of achieving high dynamic capacity of a silicene electrode for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Summary: The high theoretical capacity of Si makes it a promising anode material for lithium ion batteries. However, the poor electrical conductivity and large volume expansion during lithiation/delithiation hinders its electrochemical performances. Herein, we report a γ irradiation treatment method to prepare P‐doped Si nanoparticles. The sample exhibits a capacity of 1698 mAh/g at 0.1 C rate after 100 cycles, which is about 3 times larger than that of undoped Si. The rate performance of γ irradiated P‐doped Si is also highly improved when compared to P‐doped Si without γ irradiation treatment. The enhanced performance can be attributed that γ irradiation can facilitate the phosphorus doping into Si lattice, which can enhance the electrical conductivity of Si. [ABSTRACT FROM AUTHOR]

Nowadays, pollution and reduction in fossil resources are major problems for world.The large number of cars which use hydrocarbons fuels is the main factor of this problem. Using of electric vehicles is a suitable solution. One of the most important parameters to calculate for electric vehicles battery is its state of charge. In this paper, a single prismatic cell of lithium ion battery in discharge cycle with electrochemical-thermal has been simulated with 3D CFD. First, numerical results are validated with experimental results of voltage and temperature. Then, the results of the electrical potential distribution in the current collector, state of charge, the lithium ion concentration in electrode, the temperature distribution and generated heat in battery are presented. [ABSTRACT FROM AUTHOR]

Summary: A high throughput mass production of separator is proposed using a well‐established unique in‐house process of roll‐to‐roll atmospheric atomic layer deposition. An ultra‐thin conformal layer of Al2O3 is deposited over the commercial Celgard (PE/PP/PE) using multi‐slit gas source head. Overall 10 nm increase is incurred in the thickness, while maintaining the porosity to ~48%. The entire process of fabrication was performed at very low temperature of 90°C. The high thermal stability of as‐modified separator is achieved at of 180°C. The separator was analyzed using X‐ray photoelectron spectrometer, electrochemical impedance spectra, and field emission scanning electron microscope. The as‐developed separator showed excellent wettability due to the surface medication in addition to robust flexibility, high conformity, and minimal thermal shrinkage. The Lithium cobalt oxide (LCO)/Graphite cells with atomic layer deposition (ALD) Celgard (Al2O3 deposited) separator delivered remarkable discharge capacity with 79.5% capacity retention after 100 cycles at 1 C as compared to the uncoated‐separator(Celgard separator), which yielded relatively less retention of ~70%. Moreover, the LCO/Graphite cells with the ALD‐Celgard separator delivered the discharge capacity of 140 mAh/g at elevated temperature (up to 80°C). [ABSTRACT FROM AUTHOR]

Internal resistance is one of the important parameters in the Li-Ion battery. This paper identifies it using two different methods: electrochemical impedance spectroscopy (EIS) and parameter estimation based on equivalent circuit model (ECM). Comparing internal resistance, the conventional parameter estimation method yields a different value than EIS. Therefore, a hysteresis-free parameter identification method based on ECM is proposed. The proposed technique separates hysteresis resistance from the effective resistance. It precisely estimated actual internal resistance, which matches the internal resistance obtained from EIS. In addition, state of charge, open circuit voltage, and different internal equivalent circuit components were identified. The least square method was used to identify the parameters based on ECM. A parameter extraction algorithm to interpret impedance spectrum obtained from the EIS. The algorithm is based on the properties of Nyquist plot, phasor algebra, and resonances. Experiments were conducted using a cellphone pouch battery and a cylindrical 18650 battery. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance of Si-based lithium ion batteries, a novel multilayer microporous three-dimensional porous carbon nanosheet (PC)/multi-walled carbon nanotube (MWCNT) (PM) composite unbonded paper fiber current collector was used to replace copper foil. PM combines the advantages of PC and MWCNTs. MWCNTs provide a good conductive path that promotes electron transport and maintains structural integrity. The three-dimensional interconnected structure of one-dimensional MWCNTs combined with two-dimensional porous PC facilitates rapid electrical/ion transport and good electrolyte penetration. Moreover, PM has a tiny nanostructure. PM is filled, adsorbed and aggregated in the surface of the paper fiber and the gaps between the paper fiber and the paper fiber, which acts to connect the paper fibers and the carrier. The paper fiber has a natural non-agglomerate advantage so that PM/paper fiber (PMP) shows excellent physical properties. The initial coulombic efficiency of the Si-PMP electrode reached 69.3% and maintained a specific discharge capacity of 755 mAh/g at a current density of 0.08 A/g with a capacity retention ratio of 65.2% after 200 cycles. [ABSTRACT FROM AUTHOR]

Tin-based materials have a high theoretical capacity as a negative electrode material for lithium-ion batteries. However, the problem of volume expansion during lithium-ion insertion and extraction has severely limited its development. In this work, sodium–tin metal–organic framework (Na–Sn-MOF) compounds were successfully synthesized by simple reflux method. And we studied the reaction mechanism of the compound as anode materials for lithium-ion batteries. The special stable structure constructed by the 1,4-benzenedicarboxylic acid ligands and larger Na+ ions will limit volume expansion of the tin effectively during the process of lithium–delithium. Therefore, the sodium–tin metal–organic framework anode material exhibits a high lithium storage capacity of 523 mAh g−1 with good cycling stability and rate capability. In addition, the Coulombic efficiency of the anode material for lithium-ion batteries is closed to 100% when the lithium ions are constantly embedded and released. This work for solving the problem of volume expansion of tin-based materials is quiet meaningful. [ABSTRACT FROM AUTHOR]

Summary: A cross‐linked MnO2 coated ZnFe2O4 hollow nanosphere composite is synthesized and controlled via a facial and handy route. The connected MnO2 nanoplates form a cross‐linked network, which is conducive to the rapid transfer of Li ions. The composite with unique architecture can not only release the strain and stress caused by the insertion and desertion of lithium ions but also greatly improve the electrical conductivity and lithium ion diffusivity. Consequently, when used as a lithium‐ion battery anode material, the electrode shows an excellent initial reversible capacity of 933.5 mAh/g with an initial coulombic efficiency of 62.5%. After 100 cycles, the reversible capacity stabilized at 605.6 mAh/g with a high capacity retention of 91% from the 20th cycle to the 100th cycle. At a high current density of 3 A/g, an excellent capacity of 390.6 mAh/g can be retained. In this case, the electrode shows broad application prospects for novel power storage systems. [ABSTRACT FROM AUTHOR]

A structurally modified cathode material for Lithium ion battery is reported in this study. This study was based on first principle calculations to study the electronic, ionic, and diffusion properties of olivine phosphate family of cathode material. The attempt was made to modify the conventionally used cathode material LiFePO4 by substituting Rare earth Gd on Fe sites. The Gd-4f's electrostatic interaction, exchange coupling, impact on lithium's intercalation, and ability to modify the crystal structure upon doping in the crystalline environment of the host have been studied and discussed in detail. The calculations on electronic structure, charge transfer between atoms, Li intercalation voltage, electron localization function (ELF) analysis, steric interaction between Li ion and metal cation (Fe and Gd) in both LiFePO4 and LiGdPO4 were carried out using prescribed methods. This trend of intercalation is related to structural relaxation in the vicinity of Gd which expedites the Li ion mobility without compromising the structural stability of the material. The analysis of interatomic steric interactions and ELF analysis helped to visualize the interactions in the cathode material. The findings of this study revealed that LiGdPO4 could be a potential candidate for its use as cathode in lithium ion battery and relevant devices. [ABSTRACT FROM AUTHOR]

Owing to high safety, low cost, nontoxicity, and environment-friendly features, LiFePO4 that is served as the lithium ion battery cathode has attracted much attention. In this paper, a novel 3D LiFePO4@C core-shell configuration anchored on carbon cloth is synthesized by a facile impregnation sol-gel approach. Through the binder-free structure, the active materials can be directly combined with the current collector to avoid the falling of active materials and achieve the high-efficiency lithium ion and electron transfer. The traditional slurry-casting technique is applicable for pasting LiFePO4@C powders onto the 2D aluminum foil current collector (LFP-Al). By contrast, LFP-CC exhibits a reversible specific capacity of 140 mAh·g-1 and 93.3 mAh·g-1 at 1C and 10C, respectively. After 500 cycles, no obvious capacity decay can be observed at 10C while keeping the coulombic efficiency above 98%. Because of its excellent capacity, high-rate performance, stable electrochemical performance, and good flexibility, this material has great potentials of developing the next-generation high-rate performance lithium ion battery and preparing the binder-free flexible cathode. [ABSTRACT FROM AUTHOR]

Driving range and fast charge capability of electric vehicles are heavily dependent on the 3D microstructure of lithium-ion batteries (LiBs) and substantial fundamental research is required to optimise electrode design for specific operating conditions. Here we have developed a full microstructure-resolved 3D model using a novel X-ray nano-computed tomography (CT) dual-scan superimposition technique that captures features of the carbon-binder domain. This elucidates how LiB performance is markedly affected by microstructural heterogeneities, particularly under high rate conditions. The elongated shape and wide size distribution of the active particles not only affect the lithium-ion transport but also lead to a heterogeneous current distribution and non-uniform lithiation between particles and along the through-thickness direction. Building on these insights, we propose and compare potential graded-microstructure designs for next-generation battery electrodes. To guide manufacturing of electrode architectures, in-situ X-ray CT is shown to reliably reveal the porosity and tortuosity changes with incremental calendering steps. The 3D microstructure of the electrode predominantly determines the electrochemical performance of Li-ion batteries. Here, the authors show that the microstructural heterogeneities lead to non-uniform Li insertion and current distribution while graded-microstructures improve the performance. [ABSTRACT FROM AUTHOR]

Li4Ti5O12 (LTO) composites modified with carbon nanotubes (CNTs) and carbon coating (LTO@C/CNTs) were synthesized by a simple solid-state reaction. The carbon-coated layers reduce the growth of the primary particles, inhibit interface side reactions and increase electron conductivity, so CNTs-modified LTO can form a conductive network and improve the diffusion path of lithium ions. The LTO@C/CNTs composites show a high-rate capability (150 mAh g−1 at 10 C, 145 mAh g−1 at 20 C) with good cycling performance (90.1% and 82.8% capacity retentions after 1000 cycles at 10 C and 20 C, respectively). In addition, superior electrochemical performance is also demonstrated in a full cell with a LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode and LTO@C/CNTs anode (97.1% capacity retentions after 200 cycles at 1 C). The carbon coating and CNTs-modified in LTO can reduce the polarization of potential difference and charge-transfer resistance, improve the diffusion coefficient of lithium ions, and lead to high rate performance and cycle stability. [ABSTRACT FROM AUTHOR]

Summary: Limited by the current power battery technology, electric vehicles show extremely poor duration performance and potential risk at low temperature, which is mainly caused by poor charging performance of lithium‐ion batteries. To explore the impact of charging process on cycle degradation at low temperatures, a cycle aging experimental scheme with different charging C‐rate (0.3C and 0.5C) under −10°C and −20°C was designed for the commercial LiFePO4 battery. The experimental batteries showed severe degradation after a few of cycles. The phenomenon of reduced internal resistance and up‐shift of the charging curve was found during the early cycle stages (0th‐20th cycle). The influence of low‐temperature cycle on battery was analyzed by the increment capacity analysis (ICA); the fast decreasing intensity of ①*II showed sharp loss of lithium ions. Those lithium ions mainly transformed into lithium plating and built up dendrites instead of reintercalating into the anode crystal structure, causing the further degradation of capacity and ohmic resistance. Degradation law was obtained by curve regression analysis in the end. [ABSTRACT FROM AUTHOR]

In this paper, the direct measurement of the orthotropic thermal conductivity on a commercial Li-ion pouch battery is presented. The samples under analysis are state-of-the art batteries obtained from a fully electric vehicle commercialized in 2016. The proposed methodology does not require a laboratory equipped to manage hazardous chemical substances as the battery does not need to be disassembled. The principle of the measurement methodology consists of forcing a thermal gradient on the battery along the desired direction and measuring the heat flux and temperature after the steady state condition has been reached. A thermoelectric device has been built in order to force the thermal gradient and keep it stable over a long period of time in order to be able to observe the temperatures in steady state condition. Aligned with other measurement methodologies, the results revealed that the thermal conductivity in the thickness direction (0.77 Wm-1K-1) is lower with respect to the other two directions (25.55 Wm-1K-1 and 25.74 Wm-1K-1) to about a factor ×35. [ABSTRACT FROM AUTHOR]

To solve the problems of fast‐charging of lithium‐ion batteries in essence, development of new electrode materials with higher lithium‐ion diffusion coefficients is the key. In this work, a novel flower‐like Ni@SnNi structure is synthesized via a two‐step process design, which consists of the fabrication of Ni cores by spray pyrolysis followed by the formation of SnNi shells via a simple oxidation–reduction reaction. The obtained Ni@SnNi composite exhibits an initial capacity of ≈693 mA h g−1 and a reversible capacity of ≈570 mA h g−1 after 300 charge/discharge cycles at 0.5 C, and maintains 450 mA h g−1 even at a high rate of 3 C. Further, it is proved that a Ni@SnNi composite possesses high lithium‐ion diffusion coefficient (≈10−8), which is much higher than those (≈10−10) reported previously, which can be mainly attributed to the unique flower‐like Ni@SnNi structure. In addition, the full cell performance (Ni@SnNi‐9h/graphite vs LiCoO2) with a capacity ratio of 1.13 (anode/cathode) is also tested. It is found that even at 2 C rate charging/discharging, the capacity retention at 100 cycles is still close to 89%. It means that Ni@SnNi‐9h is a promising anode additive for lithium‐ion batteries with high energy density and power density. [ABSTRACT FROM AUTHOR]

The effect of second anodization on anodically fabricated TiO2 microcones is investigated with the aim of enhancing the lithium‐ion battery performances; these microcones are treated with a trace concentration of an electrolyte of HClO4. Unlike in the case of second anodization in H2SO4 or H3PO4, which leads to breakdown of the structures of the microcones, the HClO4‐treated TiO2 microcones maintain their unique morphological crystalline structures; this enables the inverse growth of an oxide layer. Particularly, protruding nanoparticles provide a large surface area and thus a higher areal capacity, wherein lithium ions can be stored; these particles are formed on the back‐hemisphere layers of the microcones with an increase in the overall thickness of the barrier oxide layer. The HClO4‐treated TiO2 microcones exhibit an areal capacity of approximately 1.6 times than that of pristine TiO2 microcones as well as an excellent cycling stability and capacity retention. [ABSTRACT FROM AUTHOR]

A new gel polymer electrolyte (GPE) based on chitosan‐lignocellulose composites with a smooth and porous structure for applications in lithium‐ion batteries was prepared. The obtained GPE matrix and GPE show excellent comprehensive performances. The GPE matrix based on the composite containing 15 % chitosan (denoted CSLC‐15) had the best performance, with liquid electrolyte uptake of up to 749.1 wt %. The ionic conductivity for corresponding GPE is 2.89 mS cm−1 at room temperature, and the lithium ion transference number is 0.90. The GPE proved promising for use in lithium‐ion batteries, offering a large electrochemical window (4.8 V) and excellent interfacial compatibility (a stable impedance value of 227.97 Ω after 30 days). Moreover, the GPE shows excellent thermal and mechanical properties, and high C‐rates capability (163.13 mAh g−1, 152.53 mAh g−1, 144.27 mAh g−1, 128.45 mAh g−1, 156.12 mAh g−1, at 0.2 C, 0.5 C, 1.0 C, 2.0 C, 0.2 C, respectively) and cycle performance (161.99 mAh g−1 at the 99th cycle of 0.2 C), which proved its suitability of use in lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

In this work, magnesium borate fiber (MBO) is used as a functional ceramic to coat onto a polypropylene (PP) separator (MBO@PP). This MBO coating layer increases the lithium‐ion transference number (tLi+) from 0.24 to 0.57 in the LiPF6‐based electrolyte due to the MBO acting as Lewis acid sites interacts with Lewis base PF6-. The increase in the tLi+ reduces the concentration polarization and promotes the migration of lithium ions. Besides, the prepared MBO@PP separator has better wettability with liquid electrolyte, the electrolyte uptake as well as thermal stability. The LiFePO4 half‐coin with MBO@PP separator not only had better cycle stability, but also had a higher capacity retention rate at high current. [ABSTRACT FROM AUTHOR]

Diffusion-induced stress caused by the insertion and extraction of lithium ions can result in the swelling, fracture, and even pulverization of the battery electrodes. However, only a few previous studies consider the phenomenon of phase transformation in an electrode and rarely take the impacts of cylindrical shape with transversely isotropic properties into account. In this paper, by researching the electronic reaction and diffusion process, a new theoretical model is established to study the stress level and mechanical behavior in cylindrical electrodes with phase transformation under galvanostatic operation. From the model, the brittle center and edge cracks are analyzed to investigate the influence of the initiation position on crack propagation. The tangential stress plays an important role in cracking on the electrodes. Furthermore, it is found for the center crack that it tends to grow more easily in the first insertion when the crack locates at the phase interface position, while for the edge crack, it tends to grow more easily in the early stage of lithium ion extraction. Moreover, manufacturing the electrodes with the appropriate property ratios, the diffusion-induced stress level and brittle crack-induced stress intensity factor value may decrease, and the electrode fracture phenomenon could be alleviated to some degree. Overall, our work provides a theoretical basis for the electrode phase transformation and cracking when the battery is working, and it may help us understand more about the internal mechanical behavior of the battery electrodes. [ABSTRACT FROM AUTHOR]

Summary: The serious capacity decay caused by structural amorphization is still a major issue for polyanion‐type lithium manganese silicates (Li2MnSiO4) as cathode material for lithium ion batteries. In this work, a new strategy for alleviating the structural instability via the introduction of excess lithium into the host crystal lattice is provided. A comprehensive study demonstrates that the required energy for the extraction/insertion of lithium ions into host crystal lattice was decreased as a result of changed local environment of cations in the compound after the excess lithium occupancy in lattice. Importantly, it was found that Li‐rich samples deliver higher reversible capacity and increased average potential than pristine sample, indicating the improved energy density of polyanion‐type Li2 + 2xMn1 − xSiO4/C. Additionally, the structure of Li2.2 sample was kept intact, while the Li2.0 sample was transformed to amorphous state at 200 mA h g−1 during the initial charging process by controlling the charge cut‐off potential. As expected, the introduction of a certain amount of excess lithium into Li2MnSiO4 is explored as a route to achieving increased capacity with more movable lithium, while maintaining its structural stability and cyclic stability. [ABSTRACT FROM AUTHOR]

Pulse charging of lithium-ion polymer batteries (LiPo), when properly implemented, offers increased battery charge and energy efficiencies and improved safety for electronic device consumers. Investigations of the combined impact of pulse charge duty cycle and frequency of the pulse charge current on the performance of lithium-ion polymer (LiPo) batteries used the Taguchi orthogonal arrays (OA) to identify optimal and robust pulse charging parameters that maximize battery charge and energy efficiencies while decreasing charge time. These were confirmed by direct comparison with the commonly applied benchmark constant current-constant voltage (CC–CV) charging method. The operation of a pulse charger using identified optimal parameters resulted in charge time reduction by 49% and increased charge and energy efficiencies of 2% and 12% respectively. Furthermore, when pulse charge current factors, such as frequency and duty cycle were considered, it was found that the duty cycle of the pulse charge current had the most impact on the cycle life of the LiPo battery and that the cycle life could be increased by as much as 100 cycles. Finally, the charging temperature was found to have the most statistically significant impact on the temporarily evolving LiPo battery impedance, a measure of its degradation. [ABSTRACT FROM AUTHOR]

In this study, we used a carbonization method to prepare biomass-based C/SiO2 composites from rice husks for use in lithium ion batteries. Carbonization was carried out at different temperatures in an N2 atmosphere and a heating rate of 5 °C min−1, and the biomass-based C/SiO2 composites were obtained. The results showed that the lithium ion batteries maintained good cycling performance under a current density of 100 mA g−1. At the same time, they had a good performance rate at different current densities. According to thermogravimetric analysis, x-ray powder diffraction patterns, Fourier transform infrared spectroscopy, Raman spectroscopy and other data for the biomass-based C/SiO2 composites, 700°C was the optimal carbonization temperature. At this temperature, some of the carbon was carbonized, and the sp2 hybridized carbon in the surface functional group was weakened. Simultaneously, the connection of sp2 hybridized carbon in C=C greatly improved the properties of the materials. According to the Brunauer–Emmett–Teller results, the biomass-based C/SiO2 composites obtained by carbonization of rice husks had micropores, which provided active sites for insertion and extraction of Li+. This method is in line with the concept of environmental protection, as carbonization is a simple process, and rice husks are by-products of processing. [ABSTRACT FROM AUTHOR]

Lithium ions were inserted into the electrodes of tin oxide to eliminate the first irreversible capacity of the Li-SnO2 batteries. The stabilizing SEI film was obtained from pre-embedding lithium. Thereby, first irreversible capacity of the Li-SnO2 batteries is prevented with significantly increasing the specific capacity and reducing the damage. As a result, the SnO2@Li/MWCNTs electrodes exhibited outstanding electrochemical performance, first discharge specific capacity reached 1700.15 mAh g−1, and the utilization rate of active materials reached as high as 95.89% at 100 mAh g−1. After 100 cycles, the specific discharge capacity remained greater than 499.94 mAh g−1, with a coulombic efficiency of 99.77%. [ABSTRACT FROM AUTHOR]

The stability of the LiCoPO4 electrode material in contact with a NASICON-type lithium ion conducting solid electrolyte having the composition Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and a wide range of electrochemical stability has been studied for the first time. We have found the optimal temperature at which there is no reaction between the starting components of the composites and they retain their chemical and thermal stability. Cosintering a mechanical mixture of synthesized single-phase LiCoPO4 and LAGP powders with a submicron particle size at 750°C, we have obtained a stable LiCoPO4/LAGP two-phase composite whose room-temperature electrical conductivity is three orders of magnitude higher than that of the lithium cobalt double phosphate. Composites based on LiCoPO4 and the LAGP ionic conductor can be regarded as promising cathode materials for all-solid-state lithium ion batteries. [ABSTRACT FROM AUTHOR]

The large-scale utilization of Li-ion batteries in electric vehicles requires urgent development of cost-effective and highperformance electrode materials. Herein, we report the synthesis of conjugated carboxylate (Li4C8H2O6) and non-conjugated carboxylate (Li4C4H2O6) by using a simple solvothermal method and its utilization as anode materials in Li-ion batteries. Atomic force microscopy reveals that as-prepared Li4C8H2O6 and Li4C4H2O6 possess a sheet-like morphology with a thickness of 3-5 nm. An initial discharge capacities of 251.7 mAh/g and 251.6 mAh/g at a current density of 50 mA/g can be obtained for Li4C8H2O6 and Li4C4H2O6, respectively. In addition, Li4C8H2O6 is combined with a small amount (5 wt.%) of graphene and nano-Si to enhance the cyclic performance and specific capacity. Consequently, Li4C8H2O6/graphene and Li4C8H2O6/nano-Si composites rendered a high discharge capacity of 350 mAh/g and 240 mAh/g, respectively, at a relatively higher current density of 100 mA/g. These results demonstrate that lithium carboxylates are promising anode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Information derived from microscopic images of Li-ion cells is the base for research on the function, the safety, and the degradation of Li-ion batteries. This research was carried out to acquire information required to understand the mechanical properties of Li-ion cells. Parameters such as layer thicknesses, material compositions, and surface properties play important roles in the analysis and the further development of Li-ion batteries. In this work, relevant parameters were derived using microscopic imaging and analysis techniques. The quality and the usability of the measured data, however, are tightly connected to the sample generation, the preparation methods used, and the measurement device selected. Differences in specimen post-processing methods and measurement setups contribute to variability in the measured results. In this paper, the complete sample preparation procedure and analytical methodology are described, variations in the measured dataset are highlighted, and the study findings are discussed in detail. The presented results were obtained from an analysis conducted on a state-of-the-art Li-ion pouch cell applied in an electric vehicle that is currently commercially available. [ABSTRACT FROM AUTHOR]

Commercial lithium ion cells are now optimised for either high energy density or high power density. There is a trade in cell design between the power and energy requirements. A tear down protocol has been developed, to investigate the internal components and cell engineering of nine cylindrical cells, with different power-energy ratios. The cells designed for high power applications used smaller particles of the active material in both the anodes and the cathodes. The cathodes for high power cells had higher porosities, but a similar trend was not observed for the anodes. In terms of cell design, the coat weights and areal capacities were lower for high power cells. The tag arrangements were the same in eight out of nine cells, with tags at each end of the anode, and one tag on the cathode. The thicknesses of the current collectors and separators were based on the best (thinnest) materials available when the cells were designed, rather than materials optimised for power or energy. To obtain high power, the resistance of each component is reduced as low as possible, and the lithium ion diffusion path lengths are minimised. This information illustrates the significant evolution of materials and components in lithium ion cells in recent years, and gives insight into designing higher power cells in the future. [ABSTRACT FROM AUTHOR]

Accurate state of charge estimation and robust cell equalization are vital in optimizing the battery management system and improving energy management in electric vehicles. In this paper, the passive balance control based equalization scheme is proposed using a combined dynamic battery model and the unscented Kalman filter based state of charge estimation. The lithium-ion battery is modeled with a 2nd order Thevenin equivalent circuit. The combined dynamic model of the lithiumion battery, where the model parameters are estimated depending on the state of charge, and the unscented Kalman filter based state of charge, are used to improve the performance of the passive balance control based equalization. The experimental results verified the superiority of the combined dynamic battery model and the unscented Kalman filter algorithm with very tight error bounds. Furthermore, these results showed that the presented passive balance control based equalization scheme is suitable for the equalization of seriesconnected lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In concentrated propylene carbonate (PC)-based electrolyte solutions, reversible lithium intercalation and de-intercalation occur at graphite negative electrodes because of the low solvation number. However, concentrated electrolyte solutions have low ionic conductivity due to their high viscosity, which leads to poor electrochemical performance in lithium-ion batteries. Therefore, we investigated the effect of the addition of 1,2-dichloroethane (DCE), a co-solvent with low electron-donating ability, on the electrochemical properties of graphite in a concentrated PC-based electrolyte solution. An effective solid electrolyte interphase (SEI) was formed, and lithium intercalation into graphite occurred in the concentrated PC-based electrolyte solutions containing various amounts of DCE, while the reversible capacity improved. Raman spectroscopy results confirmed that the solvation structure of the lithium ions, which allows for effective SEI formation, was maintained despite the decrease in the total molality of LiPF6 by the addition of DCE. These results suggest that the addition of a co-solvent with low electron-donating ability is an effective strategy for improving the electrochemical performance in concentrated electrolyte solutions. [ABSTRACT FROM AUTHOR]

Sodium molybdate (Na−Mo−O) wrapped by graphene oxide (GO) composites have been prepared via a simple in‐situ precipitation method at room temperature. The composites are mainly constructed with one dimension (1D) ultra‐long sodium molybdate nanorods, which are wrapped by the flexible GO. The introduction of GO is expected to not merely provide more active sites for lithium‐ions storage, but also improve the charge transfer rate of the electrode. The testing electrochemical performances corroborated the standpoint: The Na−Mo−O/GO composites delivers specific capacities of 718 mAh g−1 after 100 cycles at 100 mA g−1, and 570 mAh g−1 after 500 cycles at a high rate of 500 mA g−1; for comparison, the bare Na−Mo−O nanorod shows a severe capacity decay, which deliver only 332 mAh g−1 after 100 cycles at 100 mA g−1. In view of the cost‐efficient and less time‐consuming in synthesis, and one‐step preparation without further treatment, these Na−Mo−O nanorods/GO composites present potential and prospective anodes for LIBs. [ABSTRACT FROM AUTHOR]

As a promising cathode material for lithium‐ion batteries, nitrogen‐rich LiNi0.8Co0.1Mn0.1O2 (NCM811) attracts great attention for its high specific capacity, but the rapid capacity decline of NCM811 in the process of charge/discharge restricts its extensive application. To alleviate the capacity decline for NCM811, a solid electrolyte LiNbO3 material with lithium‐ion diffusion and electron conduction activity was successfully coated on the surface of NCM811 by adopting a simple two‐step method, and the amount of the LiNbO3 coating layer was investigated. Powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy were used to characterize the as‐prepared cathode materials. The experimental results revealed that the LiNbO3 played a role in reducing surface residual alkalis and protecting NCM811 from erosion by electrolyte. When the weight ratio of LiNbO3 and NCM811 was 1 %, the corresponding 1 wt % LNO@NCM material displayed the best cycle performance and rate capability, whose capacity retention at 1 C after 200 cycles, and discharge capacity at 10 C are 90.1 % and 122.7 mAh g−1, respectively. [ABSTRACT FROM AUTHOR]

Quantitative experiments of lithiation/delithiation rates were considered for a better understanding of electrochemical intercalation/deintercalation processes in laser structured thick film cathodes. Besides galvanostatic cycling for evaluation of specific discharge capacities, a suitable quantitative approach for determining the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by chemical diffusion coefficient values. For this purpose, the galvanostatic intermittent titration technique has been involved. It could be shown that laser structured electrodes provide an enhanced chemical diffusion coefficient and an improved capacity retention at high charging and discharging rates. [ABSTRACT FROM AUTHOR]

The porous erythrocyte-like CuCo2O4 was first prepared in this work by a convenient solvothermal post-calcination method used polyvinylpyrrolidone (PVP) as structure-directing agent and ethanol as solvent. When used as anode active materials of Li-ion batteries (LIBs), that 973 Ah/kg of reversible capacity and above 98% of coulombic efficiencies were made by the porous erythrocyte-like CuCo2O4 at 0.5 A/g of current density over 300 times. And cycling at 0.1 A/g of current density the starting specific discharge and charge capacities were 1428 and 1052 Ah/kg higher than theoretical capacity. Excellent cycling performance kept 96% of the reversible capacity retention. The superior rate performances were made at 0.1, 0.2, 0.5, 1, 2 and 0.1 A/g of current densities for 15 times. These exceptional electrochemical performances are all related to its particular compacted morphology and mesoporous spinel structure. [ABSTRACT FROM AUTHOR]

Porous biochar for anode material of lithium ion battery (LIBs) was prepared from wheat straw, one of the most common biomass of agricultural waste in China, with KOH using as activator. Microstructure of the porous biochar was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as Brunauer–Emmett–Teller (BET). The porous biochar prepared contains parallel microporous channels derived from wheat straw. These microchannel structures offer the advantage of facilitating the transport of electrolyte ions and providing more active sites. Meanwhile, the electrochemical properties were investigated by galvanostatic charge–discharge (GCD) curves, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The specific capacitance of biomass carbon activated by KOH reaches 271.7 F g−1 at scanning rate of 1 mv s−1. After 100 cycles at 0.1 °C rate, the discharge capacity of lithium-ion battery prepared is 310 mA h g−1, which shows that the material has good rate performance and cycle stability. The samples prepared by this method have a rich pore structure, can improve the permeability of electrolyte, increase the reactive sites, and increase the free movement space of lithium ions and charges, which is conducive to the improvement of electrochemical properties. [ABSTRACT FROM AUTHOR]

Among all ionic liquids (ILs) which can be used as electrolyte solvents in Li-ion batteries (LIB), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, [C2mim][FSI], is certainly the most noteworthy. One reason for that is driven by its exceptionally low viscosity, which enhances its intrinsic conductivity and makes it a good solvent for the formulation of safer electrolytes in LIB in comparison with classical organic solvents. The solubility of lithium salts in [C2mim][FSI] can be very high (more than 4 mol·L−1 for LiFSI), which opens the field to the use highly concentrated electrolyte solutions containing only ions. With the aim of comparing the physico-chemical properties of different FSI based ILs and the electrolytes obtained by addition of a doping Li-salt, three [FSI] based ILs were selected: [C2mim][FSI], N-propyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide [C3mpyrr][FSI] and N-butyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide [C4mpyrr][FSI]. For comparison, a TFSI based IL ([C4mpyrr][TFSI]) and a reference alkylcarbonate mixture (ethylcarbonate (EC)/propylcarbonate (PC)/dimethylcarbonate (DMC) (in the proportion 1/1/3 by weight) are also studied. LiFSI or lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) were used as doping lithium salts. The following physico-chemical properties have been investigated: density, viscosity, ionic conductivity, ionicity and transference number. From these results, it can be concluded that all [FSI] based ILs considered in this work exhibit both a relatively low viscosity, a high conductivity, a high ionicity and Li-ion transference number. All these properties make them good candidates for use as electrolyte in Li-ion batteries. Moreover their great thermal stability and low flammability give them an advantage over classical organic solvents. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have the greatest surface to volume ratio and are sought for a number of applications including electrodes in electrochemical storage. Understanding the mobility and chemical exchange characteristics of such layers with ionic charge carriers is vital for electrochemical functionality. Li-decorated b-As has been proposed as a promising material due to fast and directional nature of Li-ion diffusion, making it suitable for use as anode material in Li-ion batteries. Pathways of Li-ion diffusion on such structures is still under debate, and for this purpose, we investigated Li-decorated monolayer and bilayer b-As to shed light on Li mobility, along the armchair and zigzag direction in particular, and estimate the relevant diffusion barriers using DFT. The calculations reveal that (1) functionalization of the surface by Li atoms is energetically favorable, (2) binding of each single Li atom occurs via 2 eV and (3) H site is found the most stable site for adsorption energy of Li-ions. The diffusion barrier of Li-ion on b-As was found to be strongly dependent on anisotropy as the energy barrier along the zigzag direction (0.2 eV) is almost four times lower than the armchair direction (0.8 eV). Moreover, the open-circuit voltage across such a layer decreases with the increase in concentration of Li-ion doping of b-As. OCV is calculated as 4 V for a Li concentration of 20% which is suitable for anode materials. We also discuss some peculiar features of the electronic structure of b-As with Li decoration. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) heterostructured materials, combining the desired advantages of individual 2D materials and eliminating the associated shortcomings, have inspired great interest in electrochemical energy storage applications. But searching a highly efficient and practical method for preparing 2D heterostructures as electrode materials is still challenging. Herein, a 2D MoS2/graphene (GR) heterostructure is synthesized through a facile and accessible self‐assembly method, which includes adsorbing ammonium thiomolybdate onto graphene oxide (GO) surface via electrostatic attraction and subsequently annealing the precursor to heterostructure. A high loading amount (86.2 %) of unilaminar MoS2 nanosheets lie on the GR sheets forming a face‐to‐face structure, and the MoS2 nanosheets exhibit a largely expanded interlayer spacing (1.0–1.2 nm) resulting from the alternately stacked structure during self‐assembly process. As a Li‐ion intercalation host, this unique MoS2/GR heterostructure exhibits pseudocapacitance‐dominated characteristics with superior kinetic performances and extremely high structural stability. These characteristics afford MoS2/GR heterostructure remarkable rate capability (155.6 mAh g−1 at 4 A g−1; 119.3 mAh g−1 at 16 A g−1) and a durable reversible capacity (over 5000 cycles). This method is suitable for mass production of MoS2/GR heterostructure and paves a way for utilizing 2D heterostructured materials in Li‐ion or other metal ion batteries. [ABSTRACT FROM AUTHOR]

As main electrochemical power sources for portable electronic devices, lithium-ion batteries (LIBs) restricted by cathode materials should be further developed for the application in electric vehicles. Despite the restrictions of low Coulombic efficiency and serious voltage fading, high-capacity Li-rich layered oxides with high voltage are still attractive cathode materials for high-energy-density LIBs. Here, spinel-phase skin is in situ generated on Fe-containing Li-rich short nanorods by employing a direct hydrothermal method. The rational design of morphology and structure features is beneficial for the removal and embedding of lithium ions. Two-dimensional nanorod structure can greatly shorten the pathway length of Li-ion diffusion and electron transport, increase the interface area between the electrode and electrolyte, and provide more free space for Li-ion storage and transmission. Large porosity between short nanorods is conducive to the penetration and infiltration of the electrolyte. Moreover, the ultrathin spinel marginal nanolayer (~ 3 nm) can provide 3D diffusion channels for Li+ ions transportation due to its fast kinetics. Good electrochemical performances are exhibited by controlling the concentration of lithium source (LiOH·H2O). Owning to this unique structure and morphology design, the prepared compound delivers a high discharge specific capacity of 247.5 mAh g−1 at 20 mA g−1 and a good rate capability. The first Coulombic efficiency and voltage fading issue are also significantly improved. These Li-rich short nanorods with spinel-phase skin are considered promising as cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

Uniform element distribution is a key factor that influences the performance of Ni‐rich cathode materials. Herein, the Ni‐rich LiNi0.8Co0.1Mn0.1O2 cathode material has been synthesized with the assistance of a micromixer, which provides ultrafast and homogeneous mixing environments to endow the products with uniform composition distribution. As‐prepared LiNi0.8Co0.1Mn0.1O2 delivered a high initial discharge capacity of 188.5 mAh g−1 at a 0.2 C rate with a 4.3 V cut‐off potential and reached 95.4 % capacity retention after 50 cycles. LiNi0.6Co0.2Mn0.2O2 and LiNi0.9Co0.1O2 synthesized through this method also exhibited reasonable electrochemical performances, which indicates the feasibility of this novel micromixer‐assisted co‐precipitation method in the synthesis of layered cathode materials. Moreover, the reaction time had been reduced from 12 h to only seconds with the assistance of the micromixers when compared to the traditional co‐precipitation method. [ABSTRACT FROM AUTHOR]

The accurate state of charge (SOC) estimation plays a significant role in charge/discharge control, balance control, and safe management of lithium-ion batteries (LIBs). However, due to the model mismatch issues, either from battery inconsistency or battery dynamic characteristics difference, the accuracy of the model-based SOC estimation method is usually unsatisfactory. To solve this problem, a joint moving horizon estimation (joint-MHE) approach that can simultaneously estimate the model parameter and state is proposed here. In this paper, the circuit-equivalent battery model is first constructed by parameterizing the circuit parameters as polynomial function of SOC. Then, by the sensitivity analysis, the update parameters are selected and added to the state-space model as additional states. Finally, the joint-MHE strategy is conducted for the simultaneous parameter and SOC estimation. To investigate the performance of the proposed method thoroughly, three model mismatch conditions are considered, including battery inconsistency, battery dynamic characteristics difference, and the combination of both. The results demonstrate that the joint-MHE approach is an effective way to solve the model mismatch problem. Moreover, compared to joint extended Kalman filtering, the proposed approach can offer a more reliable, robust, and accurate SOC estimation of LIBs under various model mismatch conditions. [ABSTRACT FROM AUTHOR]

Lithium manganese silicate (Li2MnSiO4) demonstrates rich polymorphism with orthorhombic Pmn21 polymorph having better crystalline ordering over orthorhombic Pmnb and monoclinic forms. In this work, Li2MnSiO4 nanoparticles with the Pmn21 phase were synthesized by hydrothermal synthesis. Powder X-ray diffraction, HRSEM, and HRTEM as well as SAXS investigations revealed crystalline, spherical nanoparticles with average diameters between 14 and 25 nm. The binding energy of surface active Mn2+ ions in Li2MnSiO4 was observed at 642.9 eV in XPS analysis. SSNMR spectroscopic results revealed isotropic peaks at − 288.5 and 295.32 ppm which are attributed to the hyperfine coupling between the Li nuclei and the unpaired electrons of the Mn2+ ions. The electrochemical properties of Li2MnSiO4 electrode were studied in various 1 M LiX (X = SO42−, NO3− and ClO4−) aqueous electrolytes at a potential window of 0.2–1 V. Studies in the Li2SO4 aqueous electrolyte demonstrated better electrochemical properties with increasing peak current values up till the 2000th cycle. Charge and discharge capacities of 77.0 and 57.7 mAh g−1 were obtained at a scan rate of 5 mV s−1 with a Li-ion diffusion coefficient of 1.61 × 10−16 cm2 s−2. A small charge transfer resistance in the Li2SO4 electrolyte was also observed in EIS measurements indicating faster charge transfer kinetics. An aqueous Li-ion Swagelok-type full cell was assembled with microcrystalline graphite as anode and Li2MnSiO4 as the cathode. 1 M Li2SO4 was used as the electrolyte. The cell delivered a charge capacity of 61.8 mAh g−1 and a discharge capacity of 52.5 mAh g−1 at a current load of 1.2 A g−1 with good capacity retention of 94.0% and a Coulombic efficiency of 99.5% over 3300 cycles. SEM image, FTIR, XPS, and discharge capacity versus coulombic efficiency plots of Li2MnSiO4 nanoparticles [ABSTRACT FROM AUTHOR]

Layered MoS2 nanostructures are outstanding anode materials for lithium-ion batteries due to their potentially high capacity. Here, we report a flexible binder-free anode for LIBs, which was fabricated from vertically standing ultrathin MoS2 nanosheet arrays grown directly on a molybdenum foil as the current collector. The self-supported MoS2 nanosheet arrays exhibit high specific capacity (1041 mAh g−1 at a current density of 0.1 A g−1), good cycling stability (maintained 84% of the initial capacity after 40 cycles) and outstanding rate performance. The excellent performance should be ascribed to the short ionic diffusion length, good contact between the electrode materials and current collector, and easy transportation of lithium ions. And it also arises from the nano-/microscale pores and extensively exposed edges that effectively accommodate for the volume change of MoS2 nanosheets during the charge-discharge processes. [ABSTRACT FROM AUTHOR]

The further development of lithium‐ion batteries is often desired to obtain higher capacities by charging to higher potentials. However, such a high potential (>4.3 V) will inevitably result in capacity loss of the LiMn2O4 cathode material over numerous cycles. In this work, degradation mechanisms of LiMn2O4 electrode cycled at different charge cut‐off potentials (4.4, 4.5, 4.6, 4.7, and 4.8 V vs. Li/Li+, respectively) have been investigated. It is found that the capacity degraded seriously after aging cycles at the cut‐off potentials (<4.6 V), especially at 4.4 V. Remarkably, a thicker cathode–electrolyte interface (CEI) film on the cathode surface can be observed when the potential reached 4.7 and 4.8 V. Thus, two degradation mechanisms are proposed, which are also verified by the calculation of the diffusion coefficient of Li+ ions (DLi+). This work demonstrates the relationship between the capacity fade and cut‐off potentials and provides a useful guidance for other cathode materials with high‐voltage operation. Two degradation mechanisms of LiMn2O4 at various cut‐off potentials are proposed: 1) the bulk structure suffers from collapse with cells charged below 4.6 V; 2) higher cut‐off potentials (4.7 and 4.8 V) resulted in a thicker CEI film and enhanced degradation. [ABSTRACT FROM AUTHOR]

Cobalt (Co) and lithium (Li) were extracted from pure LiCoO2 powders and actual cathode material powders from the spent lithium-ion batteries (LIBs) after L-ascorbic acid dissolution via a mechanical activation process. The influences of activation time and rotation speed on the leaching were discussed. The mechanism of the improved leaching yield was proposed based on the characterization analysis including X-ray diffraction, scanning electron microscope, BET-specific surface area and particle size analyzer. The reduced particle size, increased specific surface area of activated samples, destroyed crystal structure and amorphous state of LiCoO2 contributed to the improved leaching efficiencies of Co and Li. With the activated process, about 99% Co and 100% Li were extracted from actual spent LIBs after 60-min grinding at 500 rpm with mild conditions. This effective process would be of great importance for recovering valuable metals from the spent LIBs at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: To enhance the rate capability and cycling stability of Si‐based materials in lithium‐ion batteries, three‐dimensional graphene nanoribbons (GNRs) enlacing Si@TiO2 nanoparticles are synthesized by magnesiothermic reduction, sol‐gel and electrostatic adsorption processes. The rigid clamping layer of TiO2 on the surface of Si prevents the whole electrode from undergoing volumetric variation. GNRs act as bridges to interconnect the adjacent Si@TiO2 nanoparticles to form a successively conductive network with decreased inner resistance. Moreover, the effect of two other kinds of carbon resources (polydopamine and resorcinol formaldehyde) on the electrochemical performance of Si@TiO2 are also discussed. The Si@TiO2@GNRs composite shows an enhanced discharge capacity of 1295 mAh g−1 at a current density of 0.5 A g−1 in the 300th cycle and achieve an outstanding rate capacity of 689.3 mAh g−1 even at 10.0 A g−1. The design of the double protecting structure provides an alternative strategy to enhance the electrochemical performance of M‐based materials (M=Si, Sn, and Ge). [ABSTRACT FROM AUTHOR]

Abstract: Understanding Li‐ion migration mechanisms and enhancing Li‐ion transport in Li2ZrO3 (LZO) is important to its role as solid absorbent for reversible CO2 capture at elevated temperatures, as ceramic breeder in nuclear reactors, and as electrode coating in high‐voltage lithium‐ion batteries (LIBs). Although defect engineering is an effective way to tune the properties of ceramics, the defect structure of LZO is largely unknown. This study reports the defect structure and electrical properties of undoped LZO and a series of cation‐doped LZOs: (i) depending on their charge states, cation dopants can control the oxygen vacancy concentration in doped LZOs; (ii) the doped LZOs with higher oxygen vacancy concentrations exhibit better Li+ conductivity, and consequently faster high‐temperature CO2 absorption. In fact, the Fe (II)‐doped LZO shows the highest Li‐ion conductivity reported for LZOs, reaching 3.3 mS/cm at ~300°C that is more than 1 order of magnitude higher than that of the undoped LZO. [ABSTRACT FROM AUTHOR]