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The high temperature cycling performance of a wide temperature electrolyte and the solid electrolyte interphase (SEI) along the cycling were investigated using a three-electrode pouch cell. The electrolyte developed in our lab demonstrated outstanding low temperature performance. The electrolyte was found to have a good and stable cycling performance at a high temperature in comparison with a state-of-the-art baseline electrolyte. Electrochemical impedance spectroscopy (EIS) was conducted on the anode, the cathode and the full cell independently with a reference embedded pouch cell. The distribution of relaxation times (DRT) transformation was calculated from the EIS spectrum. An equivalent circuit model was used to fit the anode EIS data and the electrochemical process on the anode was revealed. We concluded that a denser SEI layer was built on the anode of the improved electrolyte.

The main bottlenecks for the application of polymer electrolyte fuel cells in electric vehicles are the high cost and the inferior performance of Nafion at high temperatures above 80 °C. In this wo...

Recycling spent lithium iron phosphate (LFP) cathodes in an economically sustainable way remains a great challenge due to their low-value elemental composition. Thus, both low-cost technology together with a high-value product are critical for the recovery of the LFP materials. In this study, the commercially mature ion-exchange (IX) method was explored to recover Li from LFP material for the first time. The feasibility of Li-H and Li-K IX reactions using strong and weak acid cation exchange resins was systematically investigated from the thermodynamic and kinetic perspectives. Different organic and inorganic acids were explored to obtain the feeding solution. The IX efficiency was greatly affected by the pH of the feeding solutions. Oxalic acid leaching solution with mild pH value and low iron impurity were determined to be the optimal feeding solution for IX reaction. The kinetics of IX and regeneration reaction were fast, and the resins can be reused several times without loss of IX capacity. Along with the P element remaining in the leaching solution, the Li-K IX reaction delivered a potential product of multi-elemental fertilizer. This simple and economical technology provides a practical recycling strategy for the spent LFP batteries.

Organic electrode materials have been considered as promising candidates for the next generation rechargeable battery systems due to their high theoretical capacity, versatility, and environmentally friendly nature. Among them, organosulfur compounds have been receiving more attention in conjunction with the development of lithium-sulfur batteries. Usually, organosulfide electrodes can deliver a relatively high theoretical capacity based on reversible breakage and formation of disulfide (S-S) bonds. In this review, we provide an overview of organosulfur materials for rechargeable lithium batteries, including their molecular structural design, structure related electrochemical performance study and electrochemical performance optimization. In addition, recent progress of advanced characterization techniques for investigation of the structure and lithium storage mechanism of organosulfur electrodes are elaborated. To further understand the perspective application, the additive effect of organosulfur compounds for lithium metal anodes, sulfur cathodes and high voltage inorganic cathode materials are reviewed with typical examples. Finally, some remaining challenges and perspectives of the organosulfur compounds as lithium battery components are also discussed. This review is intended to serve as general guidance for researchers to facilitate the development of organosulfur compounds.

Safety concerns have severely impeded the practical application of high-energy-density lithium-based batteries. Dendrite growth and overcharging can lead to particularly catastrophic thermal failure. Here we report an organic cation, trisaminocyclopropenium (TAC), as a bi-functional electrolyte additive to suppress dendrite growth and offer reversible overcharge protection for metallic lithium-based batteries. During the Li plating process, TAC cations with aliphatic chains can form a positively charged electrostatic shield around Li protrusions, repelling the approaching Li(+) and thereby attaining a more uniform plating. A two times longer cycle life of 300 h at 1 mA cm(−2) is achieved in a Li|Li symmetric cell in comparison with the control. During the overcharging process, the redox-active TAC can repeatedly shuttle between two electrodes, maintaining the cell voltage within a safe value. A solid protection of 117 cycles (~1640 h) at 0.2 C with a 100% overcharge is achieved in a LiFePO(4)/Li(4)Ti(5)O(12) cell. This study sheds fresh light on the ability of organic cations to build safer batteries.

SnO2 is an attractive anodic material for advanced lithium-ion batteries (LIBs). However, its low electronic conductivity and large volume change in lithiation/delithiation lead to a poor rate/cycling performance. Moreover, the initial Coulombic efficiencies (CEs) of SnO2 anodes are usually too low to build practical full LIBs. Herein, a two-step hydrothermal synthesis and pyrolysis method is used to prepare a SnO2/C nanocomposite, in which aggregated SnO2 nanosheets and a carbon network are well-interpenetrated with each other. The SnO2/C nanocomposite exhibits a good rate/cycling performance in half-cell tests but still shows a low initial CE of 45%. To overcome this shortage and realize its application in a full-cell assembly, the SnO2/C anode is controllably prelithiated by the lithium-biphenyl reagent and then coupled with a LiCoO2 cathode. The resulting full LIB displays a high capacity of over 98 mAh g-1LCO in 300 cycles at 1 C rate.

Controlled chemical prelithiation of high capacity phosphorous/carbon (P/C) composite anode has been applied to develop advanced lithium-ion batteries (LIBs). The initial coulombic efficiency (CE) of P/C is significantly improved (up to 93% for fully-prelithiated P/C) owing to the formation of an artificial solid electrolyte interface (SEI) layer, which is characterized by SEM, Raman and XPS analyses. It ensures the application of P/C anode in real battery assembly. A partly-prelithiated P/C anode prepared by 20 s prelithiation treatment is paired with a LiCoO2 (LCO) cathode. The full cell delivers a highly reversible capacity of ~104 mAh g−1LCO at 1C rate and retains a CE close to 100% over 2000 cycles. Moreover, a fully-prelithiated P/C anode prepared by 10 min prelithiation treatment is paired with a high-capacity Li-free sulfur/carbon (S/C) cathode. This newly configured full cell delivers a good rate and cycling performance and a high energy density of 358 Wh kg−1.

A thin hollow C (HC) was synthesized to host a high phosphorus (P) loading of 75 wt%, forming a P@HC yolk/shell structure, which delivered a reversible capacity of 841 mA h g−1, with excellent rate capability and stable cycling performance. P vapor concentration was found to be critical to the formation of P@HC or the P nanorod (PNR)/C composite. At a very high concentration of P vapor, well-crystallized PNRs were formed, which, however helped to identify the potassiation mechanism.

Ni-rich layered cathode materials are at the forefront to be deployed in high energy density Li-ion batteries for the automotive market. However, the intrinsic poor structural and interfacial stability during overcharging could trigger violent thermal failure, which severely limits their wide application. To protect the Ni-rich cathode from overcharging, we firstly report a redox-active cation, thioether-substituted diaminocyclopropenium, as an electrolyte additive to limit the cell voltage within the safe value during overcharging. The organic cation demonstrates a record-breaking electrochemical reversibility at ∼4.55 V versus Li+/Li and solubility (0.5 M) in carbonate-based electrolyte. The protection capability of the additive was explored in two cell chemistries: a LiNi0.8Co0.15Al0.05O2/graphite cell and a LiNi0.8Co0.15Al0.05O2/silicon–graphene cell with areal capacities of ∼2.2 mA h cm−2 and ∼3 mA h cm−2, respectively. With 0.2 M addition, the LiNi0.8Co0.15Al0.05O2/graphite cell survived 54 cycles at 0.2C with 100% overcharge. Moreover, the cell can carry an utmost 4.4 mA cm−2 (2C) with 100% overcharge and a maximum capacity of 7540% SOC at 0.2C.

Rechargeable lithium-ion batteries have built much of our modern society. Developing high-loading and high-energy batteries have become an inevitable trend to satisfy the ever-growing demand of energy consumption. However, issues related to mechanical instability and electrochemical polarization have become more prominent accompanying the increase of electrode thickness. How to establish a robust and rapid charge transport network within the electrode architecture plays a vital role for the mechanical property and the reaction dynamics of thick electrodes. In this review, principles of charge transport mechanism and challenges of thick electrode development are elaborated. Next, recent progress on advanced electrode architecture design focused on structural engineering is summarized. Finally, a transmission line model is proposed as an effective tool to guide the engineering of thick electrodes.

Sodium-ion batteries are potential alternatives to lithium-ion batteries due to the natural abundance, and relatively low cost, of sodium. When used as a Na-ion battery cathode material, P2-type Na0.67Mn0.65Fe0.35O2 (NMFO) displays high reversible capacity (185 mAhg−1) and undergoes structural transitions between P63/mmc, P63 (OP4) and orthorhombic Cmcm during charge-discharge cycling between 1.5 and 4.3 V. Using Rietveld crystal structure refinement, we report that these structural transitions are completely suppressed in Na0.67Mn0.625Fe0.25Ni0.125O2 (NMFNO) during cycling. Interestingly, during discharge to 1.5 V, a mixture of two separate P63/mmc phases appears. Reversible capacity and specific energy of NMFNO are superior up to 100 cycles in the 1.5–4.0 V range, and to at least 200 cycles for 2.0–4.0 V. NMFNO displays first-cycle specific energy of 335 Whg−1, compared with 275 Whg−1 for NMFO. Scanning Electron Microscopy of the cathode surfaces after 200 cycles reveals performance-eroding cracks, and a solid electrolyte interface (SEI). Electrochemical Impedance Spectroscopy (EIS) shows that the total impedance of NMFNO between 1000 kHz and 0.1 Hz is significantly lower than NMFO after 200 cycles. We conclude that Ni substitution stabilizes the crystal structure by suppressing structural transitions in NMFO during cycling.

This study reports an ambient-air-tolerant approach for negative electrode prelithiation by using 1 M lithium-biphenyl (Li-Bp)/tetrahydrofuran (THF) solution as the prelithiation reagent. Key to this strategy are the relatively stable nature of 1 M Li-Bp/THF in ambient air and the unique electrochemical behavior of Bp in ether and carbonate solvents. With its low redox potential of 0.41 V vs Li/Li+, Li-Bp can prelithiate various active materials with high efficacy. The successful prelithiation of a phosphrous/carbon composite electrode and the notable improvement in its initial Coulombic efficiency (CE) demonstrates the practicality of this strategy.

A lithium ion supercapacitor full cell is fabricated with a Fluorine-doped carbon encapsulated SiOx as anode and a Nitrogen-doped carbon with hierarchical meso-micro porous structure as cathode. Benefited from the fast kinetic lithium reaction as well as longevity in the newly synthesized Si-base anode and high capacitance on the porous carbon, the hybrid device delivering of high power density, high energy density and super long cycle life is demonstrated. After prelithiation of Si-base anode, this hybrid supercapacitor exhibits a high capacity of 120 mAh g−1 at 0.2 A g−1 after 1600 cycles. A capacity of 42 mAh g−1 can still be obtained even under the current density of 3 A g−1. Furthermore, Super long cycle life (45 mAh g−1 capacity with 1 A g−1 after 10,000 cycles), low leakage current (3.8 μA) and low self-discharge (82% voltage retention after 48 h resting in open-circuit potential) are revealed. This work presents not only a simple route for the synthesis of Si-base anode for energy storage devices on lithium chemistry, but also a new approach to the construction of hybrid battery-capacitor device.

The ever-growing market of portable electronics and electric vehicles has spurred extensive research for advanced lithium-ion batteries (LIBs) with high energy density. High-capacity alloy- and conversion-type anodes are explored to replace the conventional graphite anode. However, one common issue plaguing these anodes is the large initial capacity loss caused by the solid electrolyte interface formation and other irreversible parasitic reactions, which decrease the total energy density and prevent further market integration. Prelithiation becomes indispensable to compensate for the initial capacity loss, enhance the full cell cycling performance, and bridge the gap between laboratory studies and the practical requirements of advanced LIBs. This review summarizes the various emerging anode and cathode prelithiation techniques, the key barriers, and the corresponding strategies for manufacturing-compatible and scalable prelithiation. Furthermore, prelithiation as the primary Li

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Overcharge abuse can trigger thermal runaway when a device is left unattended. Redox shuttles, as economic and efficient electrolyte additives, have been proven to provide reliable and reversible protection for state-of-art Li-ion batteries (LIBs) against overcharge. Here, a functional organic salt, trisaminocyclopropenium perchlorate (TAC•ClO(4)), is developed and employed as a redox shuttle for overcharge protection in a Na-ion battery system. This type of novel redox shuttle molecule is reported for the first time. As a unique ionic compound with the smallest aromatic ring structure, TAC•ClO(4) exhibits distinctive attributes of fast diffusion, high solubility, and ultrahigh chemical/electrochemical stability in both redox states. With merely 0.1 M TAC•ClO(4) in electrolyte, Na(3)V(2)(PO(4))(3) cathode can carry overcharge current even up to 10C or 400% SOC. Na(3)V(2)(PO(4))(3)/hard carbon cells demonstrated strong anti-overcharging ability of 176 cycles at 0.5C rate and 54 cycles at 1C rate with 100% overcharge. Moreover, TAC•ClO(4) addition has little impact on the electrochemical performance of Na-ion batteries, especially on the rate performance and the initial Columbic efficiency. Interestingly, a unique and reversible electrochromic behavior of TAC•ClO(4) electrolyte can promptly provide the device an overcharge alarm under a designed potential to further enhance the safety level.

As one of the potential alternatives to graphite, non-graphitizable hard carbon (HC) is of great interest for its high capacity and better rate performance. It is generally accepted that the higher capacity of HC comes from the random arrangement of single graphene layers, which provides extra voids to accommodate lithium.1 However, its practical application is hindered by a large irreversible capacity and thus low initial Coulombic efficiency (ICE) (2 Chemical prelithiation is one of the most effective method to compensate the Li loss and thus improve the ICE. It refers to the application of Li-containing reagents with strong reducing capabilities, which transfer the Li ions to the anode materials along with the redox reaction.3-4 The operation is rather simple and shows great potential for industrial application with a suitable roll-to-roll design. In this study, the chemical prelithiation reagent, Li-biphenyl-tetrahydrofuran, was evaluated for its prelithiation capability in hard carbon electrodes through the immersion method. The prelithiation extent can be easily controlled by tuning the reaction time. A short time of 30 s results in a high ICE of ~106% in half cell. The improvement of ICE was evaluated in full cells as well. When matched with a LiNi1/3Co1/3Mn1/3O2 cathode, the full cell with the prelithiated hard carbon anode exhibits a much improved ICE and cycling performance than those of the pristine full cell. SEM, XPS, and EIS analysis were conducted to investigate the SEI difference between pristine and prelithiated samples, and the prelithiation mechanism was proposed. References (1) Nagao, M.; Pitteloud, C.; Kamiyama, T.; Otomo, T.; Itoh, K.; Fukunaga, T.; Tatsumi, K.; Kanno, R. Structure Characterization and Lithiation Mechanism of Nongraphitized Carbon for Lithium Secondary Batteries. J. Electrochem. Soc. 2006, 153, A914-A919. (2) Xing, W.; Dahn, J. R. Study of Irreversible Capacities for Li Insertion in Hard and Graphitic Carbons. Journal of The Electrochemical Society 1997, 144, 1195-1201. (3) Scott, M. G.; Whitehead, A. H.; Owen, J. R. Chemical Formation of a Solid Electrolyte Interface on the Carbon Electrode of a Li‐Ion Cell. J. Electrochem. Soc. 1998, 145, 1506-1510. (4) Tabuchi, T.; Yasuda, H.; Yamachi, M. Li-doping process for LixSiO-negative active material synthesized by chemical method for lithium-ion cells. J. Power Sources 2005, 146, 507-509.

Potassium-ion batteries recently start to attract attention because potassium is abundant in the Earth’s crust and the commercial graphite anode works well in potassium-ion batteries. However, the ...

Sodium and potassium ion batteries (SIBs and PIBs) hold promise as potential low-cost and large-scale energy storage devices due to the earth abundance of sodium and potassium. Among all proposed anode materials, red phosphorus (P) has been recognized as a promising candidate owing to its high theoretical capacities for use in both SIBs and PIBs (2596 mA h g−1 for Na3P and 843 mA h g−1 for KP); however, its intrinsic insulating property and large volume change during cycling lead to poor cycling and rate performance. To overcome these issues, we have designed and synthesized a carbon nanotube-backboned mesoporous carbon (TBMC) material for the impregnation of red P. The TBMC was synthesized by a synchronic growth of resorcinol-formaldehyde resin/SiO2 on carbon nanotubes, followed by carbonation of the resin and removal of the SiO2. The resulting TBMC was then infiltered with red P at elevated temperatures, forming a P@TBMC composite. In this unique composite, multi-walled carbon nanotubes facilitate the electron transfer due to the high content of sp2 carbon, while the mesoporous carbon layers offer voids to load appropriate amounts of P but leave enough space to alleviate the huge volume change of the P upon sodiation/potassiation. Therefore, the P@TBMC composite exhibits excellent cycling performance and rate capability as the anode for both SIBs and PIBs. For example, the P@TBMC composite shows a high reversible desodiation capacity (~ 1000 mA h g−1 at 0.05 A g−1), superior rate performance (~ 430 mA h g−1 retained at 8 A g−1), and excellent cycle life (no capacity decay for 800 cycles at 2.5 A g−1). More impressively, the P@TBMC, as an anode of PIBs, exhibits electrochemical performance superior to all the reported anodes for PIBs, namely, delivering a reversible capacity of ~ 500 mA h g−1 0.05 A g−1 and a stable capacity of 244 mA h g−1 at 0.5 A g−1 for 200 cycles. The design based on confining active materials into hybrid carbon nanostructures integrated with highly conductive sp2 carbon and porous carbon is expected to shed light on the development of high-performance electrode materials for metal-ion batteries and other energy storage systems.

High performance liquid chromatography (HPLC) can be used to systematically and rapidly screen the potential additives for the inhibition of the polysulfide shuttle effect in a Li-S battery. The method is proven effective by investigating the 18 compounds which were reported in the literature as redox shuttle inhibitors for Li-S batteries. The change of the polysulfide ions from being exposed to 18 different redox shuttle inhibition additives was qualitatively and quantitatively determined. The changes of polysulfide species and elemental sulfur were successfully used to study the inhibition effect of the additives in Li-S batteries. It was confirmed that nitrate salts under the same concentration showed the best inhibition effect for the polysulfide shuttle reaction. However even in the electrolyte with nitrate additives, the shuttle reactions between Li metal and polysulfides (and elemental sulfur) are still notable, and thus the search for a better polysulfide shuttle inhibitor is ongoing and critical for improving the electrochemical performance of Li-S batteries.

In this report, we demonstrate that the low temperature power capability of a Li-ion battery can be substantially improved not by adding commercially unavailable additives into the electrolyte, but by rational design of the composition of the most commonly used solvents. Through the detail analysis with electrochemical impedance spectroscopy, the formation of a homogenous solid electrolyte interface (SEI) layer on the carbon anode surface is found to be critical to ensure the performance of a Li-ion battery in a wide temperature range. The post mortem analysis of the negative electrode by XPS revealed that all the electrolyte compositions form similar compounds in the solid electrolyte interphase. However, the electrolytes which give higher capacities at low temperature showed higher percentage of LiF and lower percentage of carbon containing species such as lithium carbonate and lithium ethylene di-carbonate. The electrolyte compositions where cyclic carbonates make up less than 25% of the total solvent showed increased low temperature performance. The solvent composition with higher percentage of linear short chain carbonates showed an improved low temperature performance. The high temperature performances were similar in almost all the combinations.

rGO wrapped SiOx with ordered meso-porous structure material is fabricated via a facile route. This meso-porous SiOx/rGO composite, used as anode in LIBs, exhibits a reversible capacity of 580 mAh g−1 under the applied current density of 100 mAg−1 up to 200 cycles. And it still can deliver a reversible capacity of 120 mAh g−1 even at 10,000 mA g−1 rate. The high cyclic stability and superior rate performance is attributed to the graphene layer as well as the inert products formed in the reduction of SiOx, which can buffer the volume expansion elastically, thus preserve the integrity of the electrode. Moreover, the ordered meso-porous structure can provide high specific surface area, sufficient void space to shorten the pathway of Li ions, improve the electrolyte penetration and enhanced the electrochemical Li ion storage.

Si is among the highest theoretical capacity anodes for lithium-ion batteries, but it suffers from huge volume expansion during lithiation. Here we report a new approach to alleviating the volume change-induced degradation of Si anodes by mixing Si with a room-temperature liquid metal (LM), namely, Ga–Sn alloy. The Ga–Sn alloy is fluid with self-healing ability, acting as the liquid buffer for the Si upon lithiation and delithiation and healing the cracks caused by the volume expansion and contraction. The resulting Si/LM composite exhibits a high capacity and excellent cyclicability. The composite anode delivers a reversible capacity of ∼670 mAh/g after 1000 cycles, with an outstanding rate capability.

As an advanced anode material for lithium-ion batteries, tin-chalcogenides receive substantial attention due to their high lithium-ion storage capacity. Here, tin chalcogenide (SnSe0.5S0.5) nanoplates are synthesized using a facile and quick polyol-method, followed by heating at different temperatures. Results show that the as-prepared of SnSe0.5S0.5 heated at temperature of 180 °C exhibits the best electrochemical performance with an outstanding discharge specific capacity of 1144 mA h g−1 at 0.1 A g−1 after 100 cycles and 682 mA h g−1 at 0.5 A g−1 after 200 cycles with a high coulombic efficiency (CE) of 98.7%. Even at a high current density of 5 A g−1, this anode material delivers a specific capacity of 473 mA h g−1. The high electrochemical performance of SnSe0.5S0.5 is shown by in-situ XRD analysis to originate from an enhanced Li+ intercalation and an alloy conversion process.

Carbon matrix (CM) derived from biomass is low cost and easily mass produced, showing great potential as sulfur host for lithium sulfur batteries. In this paper we report on a dihydrogen phosphate modified CM (PCM-650) prepared from luffa sponge (luffa acutangula) by phosphoric acid treatment. The phosphoric acid not only increases the surface area of the PCM-650, but also introduces dihydrogen phosphate onto PCM-650 (2.28 at% P). Sulfur impregnated (63.6 wt%) PCM-650/S, in comparison with samples with less dihydrogen phosphate LPCM-650/S, shows a significant performance improvement. XPS analysis is conducted for sulfur at different stages, including sulfur (undischarged), polysulfides (discharge to 2.1 V) and short chain sulfides (discharge to 1.7 V). The results consistently show chemical shifts for S2p in PCM-650, suggesting an enhanced adsorption effect. Furthermore, density functional theory (DFT) calculations is used to clarify the molecular binding: carbon/sulfur (0.86 eV), carbon/Li2S (0.3 eV), CH3-O-PO3H2/sulfur (1.24 eV), and CH3-O-PO3H2/Li2S (1.81 eV). It shows that dihydrogen phosphate group can significantly enhance the binding with sulfur and sulfide, consistent with XPS results. Consequently a CM functionalised with dihydrogen phosphate shows great potential as the sulfur host in a Li-S battery.

Metal sulfides are considered as promising anode materials for sodium ion batteries owing to their good redox reversibility and relatively high theoretical capacity. However, their cycle life and rate capability are still unsatisfactory because of poor conductivity and a large volume change during the discharge/charge processes. A facile method for preparing dual carbon-protected metal sulfides is reported. Metal diethyldithiocarbamate complexes are used as precursors. The synthesis only involves a co-precipitation of metal diethyldithiocarbamate complexes with graphene oxide and a subsequent thermal pyrolysis. As an example, N-doped carbon-coated iron sulfides wrapped in the graphene sheets (Fe1−xS@NC@G) are prepared and used as the anode material for a sodium ion battery. The as-synthesized Fe1−xS@NC@G electrode exhibits a high reversible capacity (440 mA h g−1 at 0.05 A g−1), outstanding cycling stability (95.8% capacity retention after 500 cycles at 0.2 A g−1), and good rate capability (243 mA h g−1 at 10 A g−1). Coupled with a Na3V2(PO4)2@C cathode, the full battery exhibits a high capacity retention ratio of 96.5% after 100 cycles and an average output voltage of ca. 2.2 V. More importantly, the proposed synthesis route is universal and can be extended to fabricate diverse transition metal sulfide-based composites with a dual carbon-protected nanostructure for advanced alkali ion batteries.

Nonaqueous redox flow batteries (RFB) can potentially achieve high energy density due to the extended operating voltage windows and redox-active material candidates. However, the development of reversible anode materials with a low redox potential and high solubility is still one of the main challenges. Here, we systematically explore polycyclic aromatic hydrocarbons (PAHs) and their corresponding radical anions (PAH˙n−) as anode redox-active couples with a combination of experimental and computational methods. The results reveal that naphthalene and its radical anion (Nap/Nap˙−) are a promising anode redox-active couple. Paired with catholytes separately containing ferrocenium hexafluorophosphate (FcPF6) and TEMPO, the resulting RFBs can provide theoretical maximum energy densities of 39 W h L−1 and 208 W h L−1, respectively, which are much higher than that of a traditional all-vanadium flow battery (25 W h L−1). As proofs of concept, both static-mode and flow-mode of the as-proposed RFBs are assembled and can deliver dozens of consecutive charge–discharge cycles.

Metal sulfides have received tremendous attention due to their superior electrochemical performance. In this study, it is the first time that the ternary tin selenium sulfide, SnSe0.5S0.5, is investigated as a potential high-performance anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The SnSe0.5S0.5/C nanocomposites have also been synthesized through a facile polyol-method followed by a simple hydrothermal process and subsequent sintering. The material demonstrated a high specific capacity and a long-term cycling stability in both Li-ion and Na-ion batteries (625 mA h g−1 for LIB at 500 mA g−1 rate after 1000 cycles, 430 mA h g−1 in a SIB at 200 mA g−1 rate after 100 cycles). Furthermore, the kinetic analysis of Li-ions and Na-ions storage revealed that the extrinsic pseudocapacitive contribution could improve the charge transfer rate during the insertion and extraction of Li-ion and Na-ion, thus enhancing the rate performance and cycling stability. These results demonstrated that the novel tin selenium sulfide (SnSe0.5S0.5) material could potentially be an excellent anode material for Li-ion storage and Na-ion storage.

Developed porosity and high-level heteroatom-doping are necessary to acquire the advanced carbon materials as sulfur hosts for lithium-sulfur batteries with high sulfur loading. We herein demonstrated that hierarchical ordered micro/mesoporous carbons with controllable porosity and nitrogen functionality could be prepared via two scalable steps which are based on aqueous self-assembly and ammonia activation processes. The effects of porosity and nitrogen doping upon the electrochemical performances of the carbon/sulfur hybrids as the cathodes in lithium-sulfur batteries were investigated. It demonstrated that the carbon materials with balanced porosity and nitrogen-doping level could effectively increase the conductivity of sulfur and alleviate the “shuttle effect” and exhibit high specific capacity, good rate performance, and superior cycling stability.

Fundamental research of sulfur redox reactions on well-defined controlled model electrode surfaces can provide new information to design high-performance lithium-sulfur batteries. Herein, we study the electrochemical reduction and oxidation of sulfur on the nanostructured HOPG electrodes with pure basal planes, step plans, and pure edge planes. Our results directly indicate that electrochemical reduction and oxidation of sulfur is significantly affected by the carbon surface structure, namely, the electrochemical reversibility of sulfur redox reaction is much better on edge plane, compared with basal plane and step plane.

A new lithium ion hybrid supercapacitor is reported, in which the negative electrode was made from ZnO nano-crystals coated with a nitrogen doped carbon, and a positive electrode composed of activated carbon. The ZnO nano-crystals were highly dispersed in a nitrogen doped carbon matrix through a bio-inspired route. Dopamine, used as the nitrogen and carbon source, self-polymerized and deposited onto the surface of ZnO nano-crystal. After pyrolysis, a nitrogen doped amorphous carbon coated ZnO nano-crystal materials were obtained. The characteristics of the synthesized carbon coated ZnO nano-crystal electrode as well as the electrochemical performance of the hybrid device were investigated. The ZnO nano-crystal structure was preserved in the course of the carbon coating. The lithium ion supercapacitor demonstrated a high capacity and good cycling stability. Such good performance can be attributed to improved conductivity, the prevention of ZnO nano particles from pulverization and the high degree of crystallinity of the ZnO material.

Benefiting from fluidity and surface tension, materials in a liquid form are one of the best candidates for self-healing applications. This feature is highly desirable for improving the life cycle of lithium-ion batteries (LIBs) because the volume expansion/contraction during the cycles of high-capacity anodes such as Si and Sn can result in mechanical fracture and lead to inferior cycle performance. Here, we report a novel room-temperature liquid metal (LM) as the anode to improve the cycle life of LIBs. The LM anode comprises an alloy of Sn and Ga, a liquid at room temperature with inherent self-healing properties, as confirmed by the in situ and ex situ analyses. Because both Ga and Sn have high theoretical capacities (769 and 990 mA h g−1, respectively), the resulting LM anode delivers a high capacity of 775, 690, and 613 mA h g−1 at the rate of 200, 500, and 1000 mA g−1, respectively. There was no obvious decay in more than 4000 cycles with a capacity of ∼400 mA h g−1 at 4000 mA g−1, realizing the best cycle performance among all metal anodes.

Full atomistic molecular dynamics simulations are performed on tetra-sulfides and undoped conjugated polymers pernigraniline base polyaniline (PNB), leucoemeraldine base polyaniline (LEB), poly (3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPY) to investigate the binding effectiveness between polysulfides and polymer binders. The weight ratio between sulfur and binder in lithium–sulfur cells is considered in 1:1 v/v mixture of dioxolane/dimethoxyethane. The simulations reveal that the end group 2 of PNB can effectively bind a lithium tetra-sulfide (i.e. Li2S4) cluster or 2 out of 43 Li2S4 molecules with the effect of solvent. However, repeat units of PNB, LEB, PEDOT and PPY seem ineffective in binding solvated Li2S4 through non-bonded interaction, especially when the concentration of tetra-sulfide/binder in a local domain of the cathode is low. Therefore, polymers with this specific functional group (i.e. the end group 2 of PNB) are suggested to be further studied as potential effective binders to inhibit the shuttle effect of solvated lithium polysulfides. Also, since the solvent has considerable impact on the binding effectiveness between tetra-sulfides and binder, it is suggested to take advantage of the explicit solvation models, such as those built in this work, to predict how other influencing factors affect binding between polysulfides and polymers.

The mechanism of the sulfur cathode in Li–S batteries has been proposed. It was revealed by the real-time quantitative determination of polysulfide species and elemental sulfur by means of high-performance liquid chromatography in the course of the discharge and recharge of a Li–S battery. A three-step reduction mechanism including two chemical equilibrium reactions was proposed for the sulfur cathode discharge. The typical two-plateau discharge curve for the sulfur cathode can be explained. A two-step oxidation mechanism for Li2S and Li2S2 with a single chemical equilibrium among soluble polysulfide ions was proposed. The chemical equilibrium among S52–, S62–, S72–, and S82– throughout the entire oxidation process resulted for a single flat recharge curve in Li–S batteries.

Lithium-rich layered oxides are promising cathode candidates for the production of high-energy and high-power electronic devices with high specific capacity and high discharge voltage. However, unstable cycling performance, especially at high charge–recharge rate, is the most challenge issue which needs to be solved to foster the diffusion of these materials. In this paper, hierarchical platelike Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials were synthesized by a facile solvothermal method followed by calcination. Calcination time was found to be a key parameter to obtain pure layered oxide phase and tailor its hierarchical morphology. The Li-rich material consists of primary nanoparticles with exposed {010} planes assembled to form platelike layers which exhibit low resistance to Li+ diffusion. In detail, the product by calcination at 900 °C for 12 h exhibits specific capacity of 228, 218, and 204 mA h g–1 at 200, 400, and 1000 mA g–1, respectively, whereas after 100 cycles at 1000 mA g–1 rate of charge an...

Fe and N dual-doped mesoporous carbon catalyst demonstrated superior catalytic activity than Pt catalyst for both oxygen reduction and oxidation reactions in alkaline electrolyte. The catalyst was synthesized through a novel simple sublimation and capillary assisted nanocasting method. Using the method, multiple transition metal and nitrogen dual-doped mesoporous carbon electrocatalysts were also successfully made. It was believed that the excellent catalytic activity was resulted from the synergistic effects of highly active metal-nitrogen species, mesoporous structure, large interfacial surface and excellent conductivity. The present synthetic strategy offers a new insight into preparation of heteroatom-doped electrocatalysts with promising applications in metal-air batteries, fuel cells, and supercapacitors as well.