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The Li-rich layered oxide is considered as one of the most promising cathode materials for high energy density batteries, due to its ultrahigh capacity derived from oxygen redox. Although incorporating over-stoichiometric Li into layered structure can generate Li2MnO3-like domain and enhance the oxygen redox activity thermodynamically, the fast and complete activation of the Li2MnO3-like domain remains challenging. Herein, we performed a systematic study on structural characteristics of Li-rich cathode materials to decipher the factors accounting for activation of oxygen redox. We reveal that the activation of Li-rich cathode materials is susceptible to local Co coordination environments. The Co ions can intrude into Li2MnO3-like domain and modulate the electronic structure, thereby facilitating the activation of Li-rich layered cathode materials upon first charging, leading to higher reversible capacity. In contrast, Li2MnO3-like domain hardly contains any Ni ions which contribute little to the activation process. The optimum composition design of this class of materials is discussed and we demonstrate a small amount of Co/Mn exchange in Li2MnO3-like domain can significantly promote the oxygen redox activation. Our findings highlight the vital role of Co ions in the activation of oxygen redox Li-rich layered cathode materials and provide new insights into the pathway toward achieving high-capacity Li-rich layered cathode materials.

Uncontrollable dendrite growth resulting from the non-uniform lithium ion (Li+) flux and volume expansion in lithium metal (Li) negative electrode leads to rapid performance degradation and serious safety problems of lithium metal batteries. Although N-containing functional groups in carbon materials are reported to be effective to homogenize the Li+ flux, the effective interaction distance between lithium ions and N-containing groups should be relatively small (down to nanometer scale) according to the Debye length law. Thus, it is necessary to carefully design the microstructure of N-containing carbon materials to make the most of their roles in regulating the Li+ flux. In this work, porous carbon nitride microspheres (PCNMs) with abundant nanopores have been synthesized and utilized to fabricate a uniform lithiophilic coating layer having hybrid pores of both the nano- and micrometer scales on the Cu/Li foil. Physically, the three-dimensional (3D) porous framework is favorable for absorbing volume changes and guiding Li growth. Chemically, this coating layer can render a suitable interaction distance to effectively homogenize the Li+ flux and contribute to establishing a robust and stable solid electrolyte interphase (SEI) layer with Li-F, Li-N, and Li-O-rich contents based on the Debye length law. Such a physical-chemical synergic regulation strategy using PCNMs can lead to dendrite-free Li plating, resulting in a low nucleation overpotential and stable Li plating/stripping cycling performance in both the Li‖Cu and the Li‖Li symmetric cells. Meanwhile, a full cell using the PCNM coated Li foil negative electrode and a LiFePO4 positive electrode has delivered a high capacity retention of ∼ 80% after more than 200 cycles at 1 C and achieved a remarkable rate capability. The pouch cell fabricated by pairing the PCNM coated Li foil negative electrode with a NCM 811 positive electrode has retained ∼ 73% of the initial capacity after 150 cycles at 0.2 C.

The fragile electrolyte/Li interface is responsible for the long-lasting consumption of Li resources and fast failure of Li metal batteries. The polymer artificial interface with high mechanical flexibility is a promising candidate to maintain the stability of the electrolyte/Li interface; however, sluggish Li-ion transportation of the conventional polymer interface hinders the application. In this work, Li-functionalized graphene oxide (GO-ADP-Li3), which is synthesized by covalent grafting of adenosine 5'-diphosphate lithium on GO nanosheets, is used as a functional additive to improve the Li-ion conductivity of the polymer artificial interface based on PVDF-HFP/LiTFSI. The enhanced Li-ion conductivity is contributed by accelerated Li-ion hopping at the surface between polymer chains and functionalized GO as well as the reduced crystallization degree of PVDF-HFP by this novel additive. The use of this modified polymer as an artificial interface on Li foil enables highly reversible Li stripping/plating and a high capacity retention of 78.4% after 150 cycles for a 0.2 A h Li metal pouch cell (Li/NCM811, strictly following practical conditions). This Li-grafted strategy on GO sheets provides an alternative for designing a compatible electrolyte/Li interface for practical Li metal batteries.

Oxygen-redox-based Li-rich layered oxide cathode materials always suffer from severe voltage decay, because of progressively structural transformation. An initial consensus is that less utilization...

Silicon based anodes are prospective candidates for high energy density lithium ion batteries, but suffer from large volume expansion during cycling which leads to rapidly capacity fading. This work proposes a self-mechanical inhibition mechanism to restrict intrinsic Li-uptake in silicon suboxides (SiO) anode with graphene wrapping, and accordingly develops SiO/graphene/C composite anodes with superior cycling stability. The composite anode containing 19 wt% graphene, owing to interaction stress between SiO and graphene during lithiation reactions, behaves only 86% Li-uptake based on SiO itself, delivers 1244 mAh g−1 reversible capacity at 0.05C, displays merely 67% volume expansion ratio (113% for SiO@C anode) after full lithiation and shows 86.2% capacity retention (44.9% for SiO@C anode) after 500 cycles at 1C. A 26.3 Ah pouch cell prepared with Ni-rich cathode and SiO/graphene/C blended graphite anode achieves energy density of 353 Wh kg−1 at 2.8-4.3 V and displays 78.1% capacity retention after 500 cycles at 0.2C.

In developing electrode materials for next-generation Li-ion batteries, significant efforts have been given to the energy, power density and cycling stability, with much less (if any) attention paid to the energy efficiency – arguably, the most important practical measure for large-scale applications. This is particularly true for the oxygen-redox active electrodes, such as Li1.2Ni0.13Co0.13Mn0.54O2, the notorious energy-inefficient cathode that has an extremely high capacity but comes with large voltage hysteresis and voltage decay. Herein, we report the rational design of an energy-efficient Li-rich layered cathode along with high energy, power density and cycling stability enabled by tuning oxygen redox activity. Specifically, the target material Li1.12Ni0.22Co0.13Mn0.52O2 exhibits an ultrahigh energy efficiency at 1 C (90.6%), high capacity (> 200 mAh g−1) with 98.9% retention and less than 150 mV decay at the extended 200 cycles. Through direct comparison between the material and Li1.2Ni0.13Co0.13Mn0.54O2, we show that the compositional change, although slightly, greatly improves the oxygen redox kinetics and reversibility, thereby boosts energy efficiency. The findings offer a strategy to narrow the gap between scientific interest and practical application of oxygen-redox chemistry.

Volume expansion and “dead Li” accumulation in the Li anode forbid the development of practical pouch-cell type Li metal batteries (pLMBs). Thus, development of highly reversible and long-life Li metal anodes is of great importance in this area. Herein, a facile thermally initiated conversion method is proposed to fabricate a Li/graphene composite anode (Li@G) by a heating induced local reaction among Li powder, graphene and PVDF. Using simple mixing–coating–drying–heating procedures, a large-area Li@G anode can be prepared in a roll-to-roll way with a film casting machine. The detailed morphology and functions of the LiC6 skeleton in this composite anode on alleviating “dead Li” accumulation are confirmed. Failure analysis and morphology characterization demonstrate the improvement in reducing cell resistance and concentration polarization by using this novel Li anode. As a result, a 0.55 A h pLMB (Li@G/NCM811) strictly following practical conditions can cycle stably 140 times due to the improved reversibility of Li stripping/plating. Moreover, a 2.6 A h pLMB (Li@G/NCM811) delivers a high energy density of 356 W h kg−1 (based on the whole cell) with a high capacity retention of 70% for 100 cycles. The scalable preparation method of the advanced Li@G anode presented in this paper makes promising progress in design and fabrication of Li composite anodes for practical pLMBs.

Li-rich layered oxides are promising positive electrode candidates for next-generation high-energy Li-ion batteries. However, they suffer from a severe gas release issue and side reaction-induced surface degradation resulting in significant capacity fade and voltage decay. Herein, this work proposes a composite surface configuration by coordinating the three different structures from Nb/Al surface doping, surface oxygen vacancies and Al2O3 layer via solution coating. A comprehensive characterization provided persuasive evidence that the composite surface configuration not only mitigates oxygen release but also regulates Li+ ion extraction/insertion during cycling. Due to the reduced side reaction and promoted surface stability, a decent specific discharge capacity of about 270 mA h g−1 at 0.1C between 2.0 and 4.6 V vs. Li+/Li was achieved with 57.0% capacity preservation after 1000 cycles at 1C. Most importantly, a 20 A h pouch cell fabricated with this surface-modified positive electrode and an SGC/Gr-negative electrode delivered 345 W h kg−1 in specific energy and retained 77.9% of it at 0.2C after 340 cycles.

Lithium metal anode is regarded as the ultimate choice for next-generation energy storage systems, due to the lowest negative electrochemical potential and super high theoretical specific capacity. However, the growth of lithium dendrite during the cycling process is still one of the most critical bottlenecks for its application. In this work, a slurry-like hybrid electrolyte is proposed towards the application for lithium metal anode, which is composed of a liquid electrolyte part and a nanometric silane-Al2O3 particle part. The hybrid electrolyte shows high ionic conductivity (3.89 × 10−3 S cm−1 at 25 °C) and lithium-ion transference number (0.88). Especially, the resistance of hybrid electrolyte decreases compared to that of liquid electrolyte, while the viscosity of hybrid electrolyte increases. It is demonstrated that the hybrid electrolyte can effectively suppress the growth of lithium dendrite. Stable cycling of Li/Li cells at a current density up to 1 mA cm−2 is possible. The hybrid electrolyte helps to uniform the lithium ion flux inside the battery and partly comes from the formation of a rigid and highly conductive hybrid interfacial layer on the surface of lithium metal. This work not only provides a fresh way to stabilize lithium metal anode but also sheds light on further research for electrolyte optimization and design of lithium metal battery system.

Lithium transition metal oxide has superior performance for oxygen evolution reaction (OER), while its activity for catalyzing oxygen reduction reaction (ORR) is too low to meet the demand of practical applications. Herein, the NCM-based (NCM, LiNi1/3Co1/3Mn1/3O2) composite materials are prepared through the two steps method. The NCM-2 (Mn2O3/LiNi1/3Co1/3Mn1/3O2) hybrid material demonstrates excellent ORR catalytic property and high OER catalytic performance, as well as the superior stability. Besides, with NCM-2 hybrid materials as catalysts of air cathode, the Al-air battery and Zn-air battery both exhibit higher power density. Therefore, based on results of Brunauer-Emmett-Teller and O2 temperature programmed desorption analysis, the improved catalytic performance ascribed to large specific surface area, pore structure and enhanced oxygen adsorption ability. In this work, the catalytic activity of lithium transition metal oxide has been improved, and a new method was provided to synthesize bifunctional catalysts for metal-air batteries.

Food media can affect the solubility of zinc oxide nanoparticles (ZnO NPs). Moreover, when a single digestive fluid and a three-step digestion system were applied to investigate the fate of ZnO NPs, several contradictory results were obtained. Here, we manipulated a novel semiclosed in vitro dynamic digestion system to investigate the difference in the released ionic zinc (Zn2+) content in three types of artificial fluids in the presence of different food media. The results show that there was a significant difference in the released Zn2+ content between the three different types of digestion systems in the presence of the same food media. In addition, the released Zn2+ content was significantly different when different types of food media were applied to the same digestion system. These results demonstrate that the different levels of released Zn2+ content can be ascribed to the difference in digestion systems and food media.

Metallic lithium anode has attracted immense attention for high energy density rechargeable batteries. However, the infinity volume change and safety issues caused by the uncontrollable growth of lithium dendrites during long-term cycling hinder its practical applications. Herein, we explore an effective strategy to solve these problems by building a secondary conductive graphene network inside the macropores of copper foam as a three-dimensional host to fabricate metallic lithium (CuFG@Li) anode. The graphene network, nested in the Cu foam, can further split the large pores of Cu foam to form micron-sized cages. After the molten lithium being infused inside the host, this graphene conductive network can be used as a deposition matrix for lithium metal in the pores and minimize the local size of lithium metal to enhance the reversibility of plating/stripping of lithium and maintain the constant volume of anode during the long cycles. The CuFG@Li anode displays stable cycling for more than 1300 h at a current density of 1 mA/cm2, and exhibits high Coulombic efficiency of 98% over 200 cycles at 1 mA/cm2, which is much better than bare Li foil anode. The CuFG@Li/LiFePO4 full cell is also fabricated and displays excellent rate performance. This strategy presents a general approach to suppress the growth of lithium dendrites and regulate the volume changes for long-lifespan lithium metal batteries.

The safety issue and poor stability induced by dendrite growth and volume change present major barriers to the practical application of lithium-metal anode for next-generation high-energy-density batteries. Herein, we propose vertically aligned ZnO nanosheets derived from zinc-based MOF grown on Ni foam (LZNF) as a lithiophilic porous scaffold to mitigate these problems. The interspace between the cross-linked ZnO nanosheets as the lithiophilic reservoir enables homogenous plating/stripping of Li at a high deposition capacity of 15 mAh cm-2, which is difficult to realize on Ni foam substrate decorated with normal ZnO particles. The integration of vertically aligned ZnO nanosheets and 3D conductive Ni foam can not only induce dendrite-free lithium deposition with reduced current density but also alleviate the volume fluctuations of lithium. Consequently, a high Coulombic efficiency in LZNF/Li half-cell (98.5% for 150 cycles at 1 mA cm-2) and enhanced cycling stability of a symmetric LZNF@Li/LZNF@Li cell (5 mA cm-2 for 250 cycles) with a small voltage hysteresis (45 mV) can be achieved. Our investigation shows that LZNF can serve as a promising multi-functional 3D host for dendrite-free Li metal anodes.

Vanadium hexacyanoferrate (VHCF) with an open-framework crystal structure is a promising cathode material for rechargeable aqueous metal-ion batteries owing to its high electrochemical performance and easy synthesis. In this paper, vanadium hexacyanoferrate cathodes were first used for constructing rechargeable aqueous sodium-ion batteries (VHCF/WO3) and tested in the new-type electrolyte (NaP-4.6) consisting of a polyethylene glycol (PEG)/H2O/NaClO4 electrolyte with a low H+ concentration (molar ratio of [H2O]/[Na+] is 4.6), which has high stability at a high current density as high as 1000 mA g-1 with a capacity retention of 90.3% after 2000 cycles at high coulombic efficiency (above 97.8%). To understand their outstanding performance, the proton-assisted sodium-ion storage mechanism and interphase chemistry of VHCF are investigated by solid-state NMR (ssNMR) technology. It is suggested that the H+ storage reaction is accompanied by the redox of vanadium atoms and Na+ intercalation is accompanied by the redox of iron atoms. It is also observed that the complex of polyethylene glycol (PEG) with Na+ (PEG-Na+) exists on the VHCF surface, which facilitates the stability of VHCF and promotes the alkali-ion transfer at a high current density. The results of the ssNMR study offer new insights into the intercalation chemistry of Prussian blue analogues with open-framework-structured compounds, which can greatly broaden our horizons for battery research.

The application of SiO anodes in Li-ion batteries is greatly restricted by its low initial coulombic efficiency (ICE). Usually, a pre-lithiation procedure is necessary to improve the ICE, but the available technologies are associated with safety issues. Metal (M)-mixed SiO shows great promise to address these issues by reactivating Li2 O through the reaction M+Li2 O→MOx +Li+ , which is the inverse reaction to that occurring at MOx anodes. Sn is found to be a good choice of metal for this concept. Nanoscale Sn-mixed SiO composites are prepared by mechanical milling. Sn forms an outstanding conductive phase, which boosts the reaction kinetics and also reactivates the Li2 O byproduct. Sn/SiO (1:2 w/w) delivers a significant improvement in ICE from 66.5 % to 85.5 %. A higher ICE value of >90 % is obtained when the Sn content is ≥50 wt %. However, additional electrolyte decomposition occurs, which is catalyzed by Sn. In addition, coarsening of the nano-Sn material reduces the inverse conversion reactivity of Sn/Li2 O and subsequently results in rapid capacity fading. The quantitative analysis indicates that, in contrast to transition metals, the alloying and dealloying nature of Sn gives a 50 % improvement in reversible capacity, attributed to Sn/Li2 O. This work gives a general strategy to choose metals for increasing the ICE of SiOx and metal oxides.

Hierarchical porous graphitic carbon material is obtained by one-step vapor-assisted catalytic graphitization accompanied with chemical activation of phenolic resin. Water vapor is used to enhance the catalytic graphitization process by etching carbon layers coated on metal nanocatalysts to maintain their high catalytic activity, and the resultant hydrogen and carbon monoxide as strong reduction gases arising from water-gas shift reaction can promote the transformation of metal ions to metal catalysts. Thus, the resultant graphitic carbon exhibits hierarchical pore structure, large surface area and high graphitic degree, which is advantageous over conventional activated carbon materials in electrochemical energy storage. The applications of hierarchical porous graphitic carbon as electrode materials for supercapacitors, and host for sulfur in lithium-sulfur cells is demonstrated, which shows remarkably enhanced electrochemical performance due to the unique structure.

A FeF2/PVDF protective layer modified metallic lithium anode was prepared by coating a hybrid layer of ferrous fluoride (FeF2) and polyvinylidene fluoride (PVDF) on the surface of the lithium foil. The morphology of the electrode before and after cycling was characterized by scanning electron microscopy (SEM). The electrochemical properties of the modified metallic lithium anode were analyzed by the galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS) and rete test. Compared with the traditional lithium foil anode, the metallic lithium anode with protective layer has no lithium dendrite and “dead lithium” on the surface after cycling. Therefore, it shows good cyclic stability, and the voltage hysteresis between charge and discharge keeps steady at 20 mV after galvanostatic (1 mA/cm2) charge/discharge cycling for 360 h. A full battery using modified metallic lithium anode and lithium iron phosphate cathode into also exhibits excellent rate performance, whose discharge specific capacity can still reach 110 mAh/g at the current density of 3 C.

SiOx due to their high theoretical specific capacity and moderate volume expansion, have been considered as alternative anode materials for next-generation Li-ion batteries. However, the electronic isolate effect originated from the huge volume variation during the repeated cycling processes results in poor cycling performance and low reversible capacity, as well as inferior rate performance. Here, we report a facile and catalyst-free synthetic route to prepare carbon coated Si nanowires connected SiOx anode materials which is supposed to address these problems. Micrometer-sized Si nanowires in-situ grow on the surface of micro-SiO at optimized temperature without catalyst assistance, following a CVD process for carbon coating. The carbon coated Si nanowires not only act as electrochemical active materials, but also efficiently accommodate the electronic isolate effect of micro-SiO particles, thus remarkably improving the electrochemical performance. As a result, the carbon coated Si nanowires connected SiOx anode exhibits high reversible capacity of ∼750 and 617.5 mAh g−1 at 0.5C and 1C (1C = 1500 mA g−1), respectively. Meanwhile, an ultrahigh capacity retention of >92% after 300 cycles is achieved at a high area mass loading of 1.8 mg cm−2.

Silicon (Si) is regarded as one of the most promising lithium-ion battery anodes to replace commercial graphite due to its exceptional theoretical capacity, appropriate voltage profile, environmental friendliness and natural abundance. It is crucial to develop effective strategies to improve the cyclic performance of the Si anodes. A new concept to synthesize Si/carbon composite with three dimensional (3D) hierarchical macro-/mesoporous structure is reported. Stober silica (SiO2) particles are used as templating agent and precursor for Si simultaneously. Unlike conventional work reported previously, here the silica particles are composited with carbon matrix before magnesiothermic reduction. Difunctional methacrylate monomers are used as solvent and carbon source coupled with a fast, environmental friendly and energy saving photo polymerization to prepare the SiO2/C composite. Based on a self-templating mechanism during the magnesiothermic reduction process, 3D hierarchical macro-/mesoporous Si is formed in situ within the carbon matrix. Compared to the Si/carbon composite composed of micro-sized Si and bare macro-/mesoporous Si, the cyclic performance is significantly improved with a reasonable mass loading density. Good rate performance is exhibited comparable to the bare porous Si. The hierarchical macro-/mesoporous structure within the carbon matrix helps to retain the porous Si structure, which effectively improves the electrochemical performance.

Summary The richness of anionic redox chemistry in the solid state offers new opportunities and a possible paradigm shift in energy storage. The excess capacity that goes beyond conventional theoretical values is attributed to the anionic redox in Li-rich transition metal oxide cathodes for Li-ion batteries. Their electrochemical behavior is thermodynamically determined by structural evolution. To better understand the electrochemical dependence on structural factors, we have induced structural modifications in pristine and electrochemically activated Li1.144Ni0.136Co0.136Mn0.544O2 through high-pressure treatment. A unique cyclical change of structural reordering is observed in the anionic redox-activated material during operando pressure sweep, characterized by a periodic evolution of superlattice peak intensity in synchrotron X-ray diffraction patterns. During the structural reordering period, the bulk compressibility of the material decreases, even becoming negative. These insights elucidate the structural flexibility and metastability of anionic redox-based materials, which can undergo large compressions and structural modifications while delivering good electrochemical properties.

The electrodeposition of lithium on heterogeneous substrates is often loose and uneven owing to the lithiophobic nature of most substrates, which causes deterioration of cell performance and ultimately cell failure. In this paper, a simple high current density induced uniform nucleation of Li on Cu substrate is presented to solve this problem. The as-obtained Li seeds with small and uniform size fully cover the surface of Cu, which is conducive to dense and even electrodeposition of Li afterwards. The LiF-rich solid electrolyte interface generated by the high current density on the Li seeds also helps to inhibit the formation of dendritic lithium. The pouch cell employing this strategy demonstrates remarkable improvement in cycling stability.

Lanthanum is a rare-earth element that has been used in various fields including medicine, agriculture and industry. Previously, in utero lanthanum exposure to dams was shown to alter neurobehavior and neurotransmitter levels in rat offspring; however, the effects of postweaning exposure to lanthanum on neurological behavior is still limited. The purpose of this study was to investigate the effects of postweaning exposure to lanthanum on neurological behavior during early adulthood in rats. Rats were orally exposed to 0, 2, 20, 60 mg/kg BW of lanthanum nitrate from postnatal day (PND) 24 to PND60. Our results indicated that lanthanum treatment significantly decreased body weight and food intake. Morris water maze test results showed that lanthanum significantly decreased escape latency and travel distance. Lanthanum treatment also significantly decreased grip strength, hindlimb strength, and running time & distance in motor activity test. Further results showed that lanthanum treatment significantly decreased plasma neurotransmitter levels of acetylcholine and norepinephrine as well as the number of neurons in the CA1 area of the hippocampus. These results suggest that postweaning exposure to lanthanum have adverse effects on neurobehaviors and the central nervous system, with no-observed-adverse-effect level at 2 mg/kg BW and benchmark dose lower confidence limit at 1.7 mg/kg BW.

Metallic lithium, with super high theoretical specific capacity, enjoys great potential as an anode for rechargeable batteries. However, safety issues caused by lithium dendrite growth as well as limited cycling life restrict its practical application. Herein we validate that the application of a new dual-salt electrolyte composed of Lithium difluorophosphate (LiPO2F2) and lithium bis(fluorosulfony)imide (LiFSI) in the same proportion enables the improved long-term cycling performance along with high coulombic efficiency for lithium metal batteries. With 1 M LiPO2F2 and 1 M LiFSI in 1,2-dimethoxyethane as the electrolyte, a Li/Cu cell can be cycled at 1 mA for more than 300 cycles with a deposited capacity of 1.0 mAh. It also displays that a homogeneous and dendrite free solid electrolyte interphase layer is generated on the Cu electrode, which can be ascribed to the favorable stability of LiPO2F2 and high ionic conductivity of LiFSI. These results deliver perceptions for the advancement of high-performance lithium metal anode.

Silicon has been regarded as one of the most promising next generation lithium-ion battery anode. However, the poor cyclic stability of the Si based anode has severely limited its practical applications, which is even worse with high mass loading density (>1 mg cm−2). A new concept has been developed to enhance the electrochemical performance of the Si nanoparticle anode. Silver nanoparticles are composited with the silicon nanoparticles in a facile way for the first time. It is found that the mechanical properties of the Si electrode have been significantly improved by the incorporation of the silver nanoparticles, leading to enhanced cyclic performance. With the Si/Ag mass ratio of 4:1, the reversible specific discharge capacity is retained as 1156 mA h g−1 after 100 cycles at 200 mA g−1, which is more than three times higher than that of the bare silicon (318 mA h g−1). The rate performance has been effectively improved as well due to excellent electron conductivity of the silver nanoparticles.

One of the crucial challenge for developing high safety and high voltage lithium ion batteries is to find a reliable electrolyte system. In this work, we report a kind of hybrid electrolytes, which are used for high-voltage lithium ion batteries and are expected to be able to effectively enhance the battery safety. The hybrid electrolytes are obtained by incorporating silane-Al2O3 (Al2O3-ST) into liquid electrolyte, which combines the merits of both solid electrolyte and liquid electrolyte. The Al2O3-ST nanoparticles help to increase lithium-ion transference number and to enhance battery safety, while liquid electrolyte contributes to high ionic conductivity. The cycling stability and rate capacity of LiNi0.5Mn1.5O4/Li batteries are improved by using the hybrid electrolytes. Nail-penetration tests indicate that LiNi0.6Mn0.2Co0.2O2/graphite battery with hybrid electrolyte owns obviously enhanced safety than that using traditional liquid electrolyte. This work provides new insight on electrolyte design for high-safety high-voltage lithium ion batteries.

The sluggish reaction kinetics occurring at the cathodes limits the performances of the metal-air batteries. Therefore, developing the oxygen electrocatalysts which can accelerate oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a critical issue. Mn-based perovskite has drawn extensive interests though their ORR and OER catalytic activity still needs to be improved. In this work, a new family of Mn-based perovskite (La1-xYxMnO3, LYM) is developed which demonstrates an improved ORR and OER catalytic activity compared with the representative strontium-doped Mn-based perovskite (LSM). For La0.9Y0.1MnO3 (LYM-10), the onset potential and half-wave potential during ORR can reach 0.909 V and 0.750 V (vs. RHE), respectively, which are more positive than those of LSM reported in most of the recent reports. Furthermore, LYM-10 also shows a better OER catalytic activity than La0.7Sr0.3MnO3 (LSM-30). In addition to its good bifunctional property, LYM-10 also achieves the superior durability compared with Pt/C during ORR, and the current retention of LYM-10 is as high as 97.3% after 43000 s. Using LYM-10 as the cathode catalyst, the alunimum-air battery can reach the maximum power density of 266 mW/cm2, and zinc-air battery can obtain low charge-discharge overpotential and the good cycling stability.

A facile scalable synthesis of hierarchical Sb/C micro-/nanohybrid has been addressed in this work, which possesses the advantages of both micrometer and nanometer scale structures as lithium-ion battery anode. Difunctional methacrylate monomers are used as solvent and carbon source as well. Liquid precursor of antimony(III) n-butoxide is dissolved in the resin monomer solution, and further incorporated into the cross-linking polymer network via photo polymerization. Through calcination in argon/hydrogen atmosphere, antimony nanoparticles are in situ formed by carbothermal reduction, and homogeneously embedded in the in situ formed micrometer sized carbon matrix. The morphology, structure, crystallinity, spatial dispersion, composition, and electrochemical performance of the Sb/C micro-/nanohybrid are systematically investigated. The cyclic and rate performance of the Sb/C micro-/nanohybrid anode have been effectively improved compared to the pure carbon anode. A reversible capacity of 362 mAh g−1 is achieved with a reasonable mass loading density after 300 cycles at 66 mA g−1, corresponding to capacity retention of 79%. With reducing mass loading density, the reversible capacity reaches 793 mAh g−1 after 100 cycles. Moreover, the electrochemical performance of Sb/C micro-/nanohybrid as sodium-ion battery anode is also investigated in this study. Sb/C hierarchical micro-/nanohybrid lithium-ion battery anode with good cyclic stability is synthesized in a scalable way using difunctional methacrylate monomers as solvent and carbon source, where a reversible capacity of 362 mAh g−1 is achieved after 300 cycles with a reasonable mass loading density, corresponding to capacity retention of 79%

Non-flammable rechargeable aqueous sodium-ion batteries (RASB) made from natural abundant resources offer promising opportunities in large-scale energy storage, yet the low energy density as well as low voltage output and the limited cycle life hinder their practical applications. Here, we develop a high-voltage RASB based on rhombohedral zinc hexacyanoferrate as cathode materials, carbon-coated NaTi2(PO4)3 as anode materials and ternary NaClO4-H2O-polyethylene glycol (Na-H2O-PEG) as electrolyte to overcome these drawbacks. Such an RASB can deliver a high voltage output of 1.6 V with a specific energy density of 59 Wh kg−1 based on the total mass of active electrode materials. In addition, it possesses an excellent rate capability as an ultra-capacitor (2.7 kW kg−1). The capacity retention more than 91% is obtained after 100 cycles. Finally, a reversible phase transformation between rhombohedral Zn3[Fe(CN)6]2 and rhombohedral Na2Zn3[Fe(CN)6]2 that are accompanied by the insertion/extraction of sodium ion in zinc hexacyanoferrate is unveiled.

Manganese oxide is one of the most extensively studied electrocatalysts for oxygen reduction reaction (ORR) due to its high abundance and environmental friendliness. In this work, cerium ion intercalated birnessite-type manganese oxide (δ-MnO2) dispersed on carbon (Ce MnO2/C) with high-efficient oxygen reduction reaction(ORR) electrocatalytic ability in alkaline media is prepared via facile aqueous reactions for the first time. The as-prepared catalyst shows morphology like quasi special nanospheres intertwined by plenty of nanorods just like knitting wool balls. Compared with MnO2/C, the onset and half-wave potential of 4.8% Ce MnO2/C shift positively 27 and 57 mV, respectively, and are close to those of Pt/C. The oxygen reduction reaction occurring on 4.8% Ce MnO2/C undergoes a 4-electron transfer pathway with the HO2− yield lee than 2%, which is much lower than that produced on Pt/C. The Ce MnO2/C catalyst also exhibits excellent long-term stability with current retention of 96.4% after aging for 40000 s. The aluminum-air battery applying 4.8% Ce MnO2/C as cathode catalyst gives out the peak power density of 348.8 mW cm−2 in 4 M KOH aqueous solution. After more than 300-h discharging, the voltage degradation of 4.8% Ce MnO2/C is only 2% per 100 h. In all, the excellent performance of the Ce-intercalated MnO2/C demonstrates its enormous potential as ORR catalyst in metal-air batteries.

MXenes, as a new family of 2D materials, can be used as film electrodes in energy storage devices because of their hydrophilic surface, metallic conductivity, and rich surface chemistries. However, the poor ion transport of MXene film electrodes causes a great loss of surface reactivity, which significantly inhibits the full exploitation of the potential of MXene-based materials. To solve this issue, we report a facile electrolyte-induced self-assembly method to construct a 3D porous structure in the MXene–rGO hybrid film, which effectively facilitates rapid diffusion and transport of electrolyte ions in the film electrode while still maintaining high electrical conductivity. When the hybrid film is employed as electrode materials for lithium-ion batteries, it exhibits high specific capacity of 335.5 mA h g–1 at 0.05 A g–1 and good rate capability of 30% capacitance retention at 4 A g–1. Additionally, the film electrode exhibits excellent cycling stability without capacity decay after 1000 cycles under hi...

Li4Ti5O12 (LTO) is regarded as a promising lithium-ion battery anode due to its stable cyclic performance and reliable operation safety. The moderate rate performance originated from the poor intrinsic electron and lithium-ion conductivities of the LTO has significantly limited its wide applications. A facile scalable synthesis of hierarchical Li4Ti5O12/C nanohybrids with supersmall LTO nanoparticles (ca. 17 nm in diameter) homogeneously embedded in the continuous submicrometer-sized carbon matrix is developed. Difunctional methacrylate monomers are used as solvent and carbon source to generate TiO2/C nanohybrid, which is in situ converted to LTO/C via a solid-state reaction procedure. The structure, morphology, crystallinity, composition, tap density, and electrochemical performance of the LTO/C nanohybrid are systematically investigated. Comparing to the control sample of the commercial LTO composited with carbon, the reversible specific capacity after 1000 cycles at 175 mA g–1 and rate performance at h...

Silicon (Si) has been regarded as one of the most promising anodes for next-generation lithium-ion batteries (LIBs) due to its exceptional capacity, appropriate voltage profile, and reliable operation safety. However, poor cyclic stability and moderate rate performance have been critical drawbacks to hamper the practical application of Si-based anodes. It has been one of the central issues to develop new strategies to improve the cyclic and rate performance of the Si-based lithium-ion battery anodes. In this work, super-small metal nanoparticles (2.9 nm in diameter) are in situ synthesized and homogeneously embedded in the in situ formed nitrogen-doped carbon matrix, as demonstrated by the Si/Ag/C nanohybrid, where epoxy resin monomers are used as solvent and carbon source. With tiny amount of silver (2.59% by mass), the Si/Ag/C nanohybrid exhibits superior rate performance compared to the bare Si/C sample. Systematic structure characterization and electrochemical performance tests of the Si/Ag/C nanohybrids have been performed. The mechanism for the enhanced rate performance is investigated and elaborated. The temperature-dependent I-V behavior of the Si/Ag/C nanohybrids with tuned silver contents is measured. Based on the model, it is found that the super-small silver nanoparticles mainly increase charge carrier mobility instead of the charge carrier density in the Si/Ag/C nanohybrids. The evaluation of the total electron transportation length provided by the silver nanoparticles within the electrode also suggests significantly enhanced charge carrier mobility. The existence of tremendous amounts of super-small silver nanoparticles with excellent mechanical properties also contributes to the slightly improved cyclic stability compared to that of simple Si/C anodes.

Hard carbon is emerging as a highly promising material for power-demanded energy storage devices. Recently, introducing heteroatom such as oxygen is confirmed to be available to improve the capacity. However, it remains a significant challenge to achieve simultaneously superior high-rate capability and long-term cycling stability. Here we demonstrate that the surface oxo-funcitionalized hard carbon spheres (o-HCS, 4.2 m2 g−1) derived from mild oxidative approach enhance pseudocapacitance lithium-ion storage with improved Li-ion diffusivity and thus exhibit high-rate capacity and long cycle life in both Li-ion batteries and Li-ion capacitors. The o-HCS electrode delivers specific capacity of around 275 mAh g−1 at 744 mA g−1 (2C) and capacity retention of above 92.0% and about 86.5% after 1100 and 1700 cycles, respectively. Impressively, it delivers above 110 mAh g−1 at extreme high current density of 14.88 A g−1 (40C). As well, o-HCS electrode in Li-ion capacitor shows a capacitance of 34.8 F g−1 (corresponding to 48.5 Wh kg−1 and 3.6 kW kg−1) at the current density of 3720 mA g−1, and after 7000 cycles the capacity retention is 96% (∼0.057% decay per cycle).

In this work, the La 0.8 Sr 0.2 Co 1-x Mn x O 3 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) perovskites (LSCM) were synthesized by a facile improved sol–gel method. The crystalline structures, morphologies, Co/Mn valence states and oxygen adsorption/desorption behavior of the LSCM materials are systematically studied, and their catalytic activities toward ORR and OER are investigated by the rotating-disk electrode (RDE) and zinc-air battery techniques. It is found that the proper substitution of Co with Mn can efficiently improve the ORR and OER activities of La 0.8 Sr 0.2 CoO 3 perovskite at the same time. The LSCM-60 catalyst exhibits the optimum bi-functional activity. It is mainly attributed to the regulation of the Bi-site Co/Mn valence states and the improvement of the oxygen adsorption/desorption capability. Besides of the good bi-functional property, LSCM-60 shows superior durability compared with Pt/C and IrO 2 catalysts. When using LSCM-60 as the cathode catalyst of zinc-air batteries, the low charge-discharge overpotential (1.05 V at 50 mA cm −2 ) and the excellent long-term cycle stability were obtained. This study exhibits the possibility to improve the bi-functional activity of La 0.8 Sr 0.2 CoO 3 through a simple doping process.

Li-rich layered oxides can deliver ultrahigh capacities which stem from a blend of cationic redox and mostly lattice oxygen redox. However, the oxygen redox reaction often leads to structure transition and oxygen release from the material surface. Herein, the surface doping of B is conducted via a molten salt method, which creates a thin reinforcement layer containing stable B–O bonds. X-ray photoelectron spectroscopy reveals that the doping of B only acts on the material surface and cannot inhibit oxygen redox in the bulk. Differential electrochemical mass spectroscopy measurement demonstrates that the surface protective layer effectively reduces the oxygen release of LLOs. A combination of X-ray diffraction and transmission electron microscope analyses confirm the enhanced structural stability. As a consequence, the target material displays a high reversible capacity of 275 mAh g−1 at 0.1C and a suppressed voltage decay rate of 2.5 mV per cycle during the first 80 cycles (at 0.2C, 2.0–4.8V). The findings highlight the essential role of stable surface oxygen framework in cycling stability, and demonstrate the effectiveness of surface reinforcement doping in reducing oxygen release.

La1-xSrxMnO3 (LSM) material has been proposed as one of the best oxygen reduction reaction catalysts (ORRCs) to substitute the noble metals. It is well known that improving oxygen adsorption capacity is beneficial to the catalytic activity of LSM perovskites. Herein, the La0.7Sr0.3MnO3@Ce0.75Zr0.25O2 (LSM@CZ) composite material has been synthetized by a facile electrostatic self-assembly method with two-step strategy. The CZ nano-particles are well distributed on the surface of LSM material. The LSM-4CZ composite catalyst exhibits good catalytic activity in alkaline solution. The onset potential, half-wave potential and electron transfer number of LSM-4CZ composite catalyst correspond to 0.898 V, 0.695 V and 4, respectively. The LSM-4CZ composite catalyst has a good durability with the current retention of 93.9% after 80000 s, exhibiting a much better stability than that of Pt/C catalyst whose retention is 83.5%. By using LSM-CZ as the ORRC, the maximum power density of the aluminum-air battery can reach 242.9 mW cm-2, which is about 40% higher than that of battery using LSM (177.3 mW cm-2). It indicates that LSM@CZ composite material is a promising cathodic electrocatalyst for metal-air batteries.

SiO x owing to high reversible capacity and moderate volume expansion has been attracting a lot of attention as state-of-the-art anodes for the next generation of Li-ion batteries. However, poor cycling performance and poor rate capability, respectively associated with detrimental volume expansion and insulative amorphous SiO 2 , are still challenging issues which need to be addressed for the actual employment as anodes for Li-ion batteries. In this regard, here we design, synthesize, characterize and test carbon coated sheet-like SiO 1.1 nanocomposites formed by Si-nanodomains confined inside amorphous SiO 2 (nano-Si/ a -SiO 2 ). As a proof-of-concept, we achieve sheet-like SiO x nanocomposites via in-situ transformation of delaminated siloxene. In particular, self-prepared siloxene with oxygen-inserted Si 6 rings terminated with H and OH ligands is prepared by delamination of CaSi 2 in dilute HCl. Importantly, the resulting carbon coated nano-Si/ a -SiO 2 material shows enhanced reaction kinetics and structural stability leading to 946 mAh g −1 capacity at 0.15 A g −1 . Intriguingly, 38.0% (~360 mAh g −1 ) of the maximum capacity is maintained even at 7.5 A g −1 , corresponding to a remarkable less than 3 min charge/discharge time. Finally, the electrode shows merely 24% of volume expansion and minor cracks with capacity retention of 92% after 300 cycles at 7.5 A g −1 .

© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The oxidative decomposition mechanism of fluoroethylene carbonate (FEC) used in high-voltage batteries is investigated by using density functional theory (DFT). Radical cation FEC•+ is formed from FEC by transferring one electron to electrode and the most likely decomposition products are CO2 and 2-fluoroacetaldehyde radical cation. Other possible products are CO, formaldehyde and formyl fluoride radical cations. These radical cations are surrounded by much FEC solvent and their radical center may attack the carbonyl carbon of FEC to form aldehyde and oligomers of alkyl carbonates, which is similar with the oxidative decomposition of EC. Then, our experimental result reveals that FEC-based electrolyte has rather high anodic stability. It can form a robust SEI film on the positive electrode surface, which can inhibit unwanted electrolyte solvent and LiPF6 salts decomposition, alleviate Mn/Ni dissolution and therefore, improve the coulombic efficiency and the cycling stability of high voltage LiNi0.5Mn1.5O4 positive electrodes. This work displays that FEC-based electrolyte systems have considerable potential replacement of the EC-based electrolyte for the applications in 5 V Li-ion batteries.

A novel La0.7Sr0.3MnO3-CeO2 (LSM-CeO2) hybrid catalyst for oxygen reduction reaction (ORR) has been synthesized by a facile one-pot method. The flower-like CeO2 with the diameter of about 3 μm is formed by the agglomeration of nanosheets with the thickness of about 40 nm. The LSM particles with the diameter of about 150 nm are well distributed on the flower-like CeO2, thus the interaction between LSM and CeO2 is built. Therefore, the LSM-CeO2 composite catalyst exhibits the much higher catalytic activity toward ORR with the direct four-electron transfer mechanism in alkaline solution than LSM or CeO2. Furthermore, the stability of LSM-CeO2 is superior to that of Pt/C, and the current retention is 93% after 100000 s. The maximum power density of the aluminum-air battery using LSM-CeO2 as the ORRC can reach 238 mW cm-2, which is about 29% higher than that with LSM (184 mW cm-2). It indicates that LSM-CeO2 composite material is a promising cathodic electrocatalyst for metal-air batteries.

Poly[bis-(ethoxyethoxyethoxy)phosphazene] (EEEP) with electro-oxidable of the P-O bond is prepared by a facile method and utilized as an electrolyte additive to enhance the cycling performance of LiCoO2 cathodes under high-voltage operations. We found that 5 wt.% EEEP made the blank electrolyte obviously reduce the flammability, as well as the capacity retention of Li/LiCoO2 half-cell assembling with the EEEP-containing electrolyte is elevated to 89.9% from 51.2% after 100 cycles at a high cutoff voltage of 4.4 V. The enhanced cycling performance of LiCoO2 cathode in the EEEP-containing electrolyte at a high potential should be ascribed to the formation of stable film on the cathode surface, resulting in suppression of the subsequent decomposition of electrolyte under high voltage working. The characterization from scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) indicates that EEEP can be electrochemically oxidized to form a robust and protective film on LiCoO2, and improve the interfacial stability of LiCoO2 cathode/electrolyte at high potentials.

The La 1-x Sr x MnO 3 (LSM) perovskites have been proposed as the promising oxygen reduction reaction catalysts (ORRCs) to substitute the noble metal. However, their ORR catalytic activities still need to be further improved. Here, the La 0.7 (Sr 0.3-x Pd x )MnO 3 (LSPM) perovskites with the substitution of Sr with Pd are synthesized by a facile sol-gel method. The structure, morphology, valence state of Mn, oxygen adsorption behaviors of the different LSPM catalysts are investigated, and their ORR catalytic activities are studied by the rotating ring-disk electrode (RRDE) and aluminum air battery technologies. The results demonstrate that the appropriate substitution of Sr with Pd can effectively improve the ORR catalytic activity of La 0.7 Sr 0.3 MnO 3 due to the regulation of the Mn valence and enhancement of the oxygen adsorption capacity. Among the LSPM perovskites, the LSPM-15 catalyst exhibits the best catalytic activity toward ORR. In addition, the current retention of LSPM-15 is as high as 98.9% after 10000 s with the generation of a few HO 2 − (0.96% ∼ 1.56%) during the whole aging test. Moreover, the maximum power density of the aluminum air battery using LSPM-15 can reach 265.6 mW cm −2 , which indicates that LSPM-15 can be used as a promising ORRC for the aluminum air batteries.

Nanosheet-constructing porous CeO2 microspheres with silver nanoparticles anchored on the surface were developed as a highly efficient oxygen reduction reaction (ORR) catalyst. The aluminum-air batteries applying Ag-CeO2 as the ORR catalyst exhibit a high output power density and low degradation rate of 345 mW cm-2 and 2.6% per 100 h, respectively.

Much attention has been focused on the fabrication of large-scale single-crystalline graphene due to its high quality and impressive physical properties, which are essential and significant in electronics and optoelectronics applications. Here, well-aligned submillimeter-sized single-crystalline graphene arrays were successfully fabricated by a commercial printing-assisted chemical vapor deposition process. In this method, carbon precursor dots can be printed on Cu foil with a designed pattern, which can serve as the nucleation centers to induce the growth of graphene domains at the designed locations. This work provides a facile route to synthesize single-crystalline graphene arrays on a large scale, which is of great significance in building graphene devices for practical applications.

Graphene, a new carbon material with the highest thermal conductivity (TC) in known materials, is a good candidate for polymer-based thermally conductive material applications. However, the homogeneous dispersion of graphene and effective construction of graphene-based thermally conductive network in the polymer matrix still remains a big challenge. In this paper, we report an effective way to avoid aggregation of graphene in polymers through the fabrication of 3D porous graphene foam (GF) in advance by a simple solvent evaporation induced self-assembly method. The as-prepared GF is proved to be an effective thermally conductive network after the epoxy perfusion, giving rise to a high TC of 11.58 W (m−1 K−1) for the GF/epoxy composite. In addition, anisotropic TC in the GF/epoxy composites is observed because of the oriented arrangement of graphene sheets in the GF due to solvent evaporation. Besides, further improvement of TC to 16.69 W (m−1 K−1) can be achieved by addition of polyvinyl pyrrolidone (PVP) during the preparation of GF, which can be ascribed to the reduction of interfacial thermal resistance by amorphous carbon generated from pyrolysis of PVP.

The development of the efficient and economical catalysts for the oxygen reduction reaction (ORR) is an important issue for the commercialization of metal-air batteries. Herein, a silver-doped d-MnO2 dispersed on carbon powder (Ag-MnO2/C) was synthesized by a facile route. The specific surface area of Ag-MnO2/C is more than three times higher than that of MnO2/C. Moreover, Ag-MnO2/C shows much higher catalytic activity toward ORR than MnO2/C or Ag/C. The half-wave potential of Ag-MnO2/C is much more positive compared with that of 20% Pt/C. Ag-MnO2/C also exhibits an excellent long-term stability and the ORR current retention keeps 97.1% after aging for 45000 s. Using Ag-MnO2/C as the ORR catalyst, the peak power density of Al-air battery reaches 315 mW cm(-2) which is almost the highest record. (C) 2017 The Electrochemical Society. All rights reserved.

For the development of high-performance Li–S batteries, the issues of the insulating nature of sulfur and shuttle effect of polysulfides need to be well addressed simultaneously, which require elaborate structure design of a suitable host for sulfur. In this work, a novel bifunctional and free-standing sulfur cathode consisted of a hierarchical porous carbon network as the conductive host for sulfur and an in situ formed graphene shell as the top layer for physical blocking of the shuttle effect is carefully fabricated. Owing to filtration assembly, an ultrathin graphene shell (∼100 nm in thickness) is in situ formed firstly, on which a macroporous graphene architecture is gradually deposited afterwards. Subsequent chemical vapor deposition of interwoven CNTs on both sides of graphene sheets generates numerous nano-sized cavities for loading of sulfur nanoparticles. The rationally designed electrode possesses a relatively high areal sulfur loading of ∼3.6 mg cm−2, and shows excellent rate capability at ∼6.0 mA cm−2 and cyclic stability over 200 cycles. And as the graphene nano-shell blocks the diffusion of polysulfides, the anti-self-discharge capability of the cell is remarkably improved.