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Rationally designed heterostructures provide attractive prospects for energy storage electrodes by combining different active materials with distinct electrochemical properties. Herein, through a phase separation strategy, a heterostructure of SnO2 encapsulated by amorphous Nb2O5 is spontaneously synthesized. Insertion-type anode Nb2O5 outer shell, playing as reaction containers and fast ionic pathways, physically inhibits the Sn atoms’ migration and enhances the reaction kinetics. Moreover, strong chemical interactions are found at the SnO2/Nb2O5 interfaces, which ensure the solid encapsulation of the SnO2 cores even after 500 cycles. When used for lithium-ion batteries, this heterostructured anode exhibits high cycling stability with a capacity of 626 mA h g−1 after 1000 cycles at 2 A g−1 (85% capacity retention) and good rate performance with the capacity of 340 mA h g−1 at 8 A g−1.

Efficient, rechargeable Mg and Ca batteries Divalent rechargeable metal batteries such as those based on magnesium and calcium are of interest because of the abundance of these elements and their lower tendency to form dendrites, but practical demonstrations are lacking. Hou et al . used methoxyethyl amine chelants in which the ligands attach to the metal atom in more than one place, modulating the solvation structure of the metal ions to enable a facile charge-transfer reaction (see the Perspective by Zuo and Yin). In full battery cells, these components lead to high efficiency and energy density. Theoretical calculations were used to understand the solvation structures. —MSL

Li10GeP2S12 (LGPS) has a high ionic conductivity and compatibility with sulfur cathodes; however, the instability of LGPS against Li and Li dendrite growth still remains unsolved. Here, we solved t...

The instability of carbonate electrolyte with metallic Li greatly limits its application in high-voltage Li metal batteries. Here, a "salt-in-salt" strategy is applied to boost the LiNO

In carbonate electrolytes, the organic-inorganic solid electrolyte interphase (SEI) formed on the Li-metal anode surface is strongly bonded to Li and experiences the same volume change as Li, thus it undergoes continuous cracking/reformation during plating/stripping cycles. Here, an inorganic-rich SEI is designed on a Li-metal surface to reduce its bonding energy with Li metal by dissolving 4m concentrated LiNO3 in dimethyl sulfoxide (DMSO) as an additive for a fluoroethylene-carbonate (FEC)-based electrolyte. Due to the aggregate structure of NO3 - ions and their participation in the primary Li+ solvation sheath, abundant Li2 O, Li3 N, and LiNx Oy grains are formed in the resulting SEI, in addition to the uniform LiF distribution from the reduction of PF6 - ions. The weak bonding of the SEI (high interface energy) to Li can effectively promote Li diffusion along the SEI/Li interface and prevent Li dendrite penetration into the SEI. As a result, our designed carbonate electrolyte enables a Li anode to achieve a high Li plating/stripping Coulombic efficiency of 99.55 % (1 mA cm-2 , 1.0 mAh cm-2 ) and the electrolyte also enables a Li||LiNi0.8 Co0.1 Mn0.1 O2 (NMC811) full cell (2.5 mAh cm-2 ) to retain 75 % of its initial capacity after 200 cycles with an outstanding CE of 99.83 %.

Carbon materials with excellent light-harvesting capacity are promising light absorbers for solar-thermal conversion. However, developing advanced carbon materials with tailored morphology and properties that are suitable for solar steam generation remains challenging. Herein, we have successfully synthesized oxygen-enriched tubular carbon with uniform hollow architecture and some defective structure by pyrolysis of a coordination complex (PEG-CaCl2 precursor). Briefly, PEG molecules can promote the anisotropic growth of CaCl2 nanorods during pyrolysis through coordination interaction (Ca–O), and simultaneously serve as the carbon and oxygen sources for in-situ growth of self-doped tubular carbon using the as-formed nanorods as ideal templates. The resulting tubular carbon with one-dimensional hollow structure, possesses a large specific surface area (613 m2 g−1) for light absorption, low thermal conductivity (0.0474 W m−1 K−1) for heat localization, and abundant hydrophilic oxygen-containing groups (8.62 at.% oxygen) for efficient water delivery. Thus, the self-floating photothermal membrane based on the tubular carbon, fabricated by the addition of agar binder, exhibits broadband light absorption (96%) and achieves a high evaporation efficiency of 91.3% under one sun illumination. This work provides a new insight to design and synthesize functionalized carbon with controlled morphology and the desired structure for potential application in solar steam generation.

Multi-walled carbon nanotubes-titanium dioxide (MWCNTs-TiO2) nanocomposites were synthesized via microwave-assisted synthesis and conventional hydrothermal method, comprising of well-crystallized a...

For energy storage system, it is still a huge challenge to achieve high energy density and high power density simultaneously. One potential solution is to fabricate electrochemical capacitors (ECs), which store electric energy through surface ion adsorption or redox reactions. Here we report a new electrode material, heavy nitrogen-doped(9.29 at.%) black titania (TiO2− x :N). This unique hybrid material, consisting of conductive amorphous shells supported on nanocrystalline cores, has rapid N-mediated redox reaction (TiO2− x Ny + z H+ + z e− « TiO2− x N y H z ), especially in acidic solutions, providing a specific capacitance of 750 F g−1 at 2 mV s−1 (707 F g−1 at 1 A g−1), great rate capability (503 F g−1 at 20 A g−1), and maintain stable after initial fading. Being a new developed supercapacitor material, nitrogen-doped black titania may revive the oxide-based supercapacitors.

A graphene tile based phase change material was reported to function as thermal storage material and light absorption material simultaneously, which achieved directly efficient solar-to-thermal con...

The design of advanced filter materials to realize worldwide access to clean air and drinking water is of imminent importance. However, complex procedures and toxic raw materials used in the manufacturing process can easily result in secondary pollution, defeating the original purpose. Herein, a green and facile table salt (sodium chloride, NaCl)-assisted pyrolysis strategy is reported to construct nanoporous carbon foam from edible feedstocks (such as agar, pectin, and flour) for use as efficient filter materials. NaCl plays a part in the pore-forming agent and rigid scaffold, which constructs the secondary porous structure while efficiently preventing the self-assembly three-dimensional network structure from thermally collapsing during pyrolysis. Taking advantage of the tailored porous structure, the agar-derived nanoporous carbon foam exhibits a high oil/organic solvent adsorption capacity of up to 202 times its own weight. Besides, an air filtration paper, composed of the obtained material and nonwoven fabric, possesses a PM2.5 filtration efficiency of over 99% with a low-pressure drop of 112 Pa, better than commercial masks. Considering the simple fabrication process and outstanding adsorption/filtration performance, the nanoporous carbon foams fabricated from sustainable precursors have great potential for environment-related applications.

Single-crystalline cathode materials have attracted intensive interest in offering greater capacity retention than their polycrystalline counterparts by reducing material surfaces and phase boundaries. However, the single-crystalline LiCoO

To work against the volume expansion (∼300%) of SnO2 during lithiation, here a sub-micro sized, interconnected, and porous SnO2 cube with rationally designed reserved space (∼375%) is synthesized via an artful topochemistry route (CaSn(OH)6-CaSnO3-SnO2). Owing to its microstructure, this novel material harvests enhanced lithium-storage performance.

In the search of high-performance anode materials for next-generation Li-ion batteries, more efforts are needed on new structural prototypes. Motivated by the negative thermal expansion effect in a loosely packed crystal structure type, we are intrigued by the possibility of exploiting new anode materials in a suitable phase structure with much-reduced intrinsic volume strain. Herein, we report a new pyrochlore phase anode material, Ce2Sn2O7, which shows atomic Sn confined in a conductive 3D percolating Ce–O framework. Based on the concept of structural openness, pyrochlore Ce2Sn2O7 possesses open structures to tolerate the volume change. Notably, the Ce–O network is quite robust against the charge/discharge process, which accounts for the high structural stability observed in the experiment. Ultimately, Ce2Sn2O7 electrodes achieve a capacity as high as 631.1 mA h g−1 and excellent cycling stability. This atom-confining strategy of atomic Sn in the conductive 3D percolating Ce–O framework might be exploited as a general strategy for reducing cycling strain in ion-storage materials.

Black TiO2−x is an attractive material due to its adjustable band structure, useful in different applications, and has been heavily investigated and developed. The current reduction of TiO2 involves a process from surface to center: thus, the issue of either insufficient or excessive reduction seems inevitable. To the best of our knowledge, it is rarely reported that a homogeneous defect distribution can be facilely achieved inside black TiO2−x. In this study, a bulk-reduced rutile TiO2−x was obtained via a circuitous two-step approach, with an intermediate Magneli phase (TinO2n−1). With the decomposition of a solid atmosphere creator (e.g. KClO4 grains) at a high temperature, the missing oxygen ions in Ti4O7 could be replenished quantitatively. The TEM and SAED results reveal that the oxidation process is not just a surface reaction, but it involves reverse displacement or structural rearrangement inside the crystal. In particular, the periodic variation of crystallographic sheer planes was the direct evidence of the above bulk reaction, i.e. unified long period for Ti4O7 and varied long period for critical ratio sample. The as-prepared samples showed different band gaps and colors, based on their oxygen content. KClO4, with a critical mixing ratio of around 17.5 mol%, could almost oxidize Ti4O7 to black rutile TiO2−x. Furthermore, the sample formed at the critical ratio showed a considerable photo-thermal response speed of 1.7 °C s−1 and an equilibrium temperature of up to 70 °C under irradiation with light above 400 nm, which can be an evidence for the enhancement of non-intrinsic absorption. In short, this study provides a new route for the controllable preparation of black TiO2−x, and a possibility for further development of other solid atmosphere creators.

Flexible electrode materials toward rational design and low-cost fabrication are crucial to energy storage applications. Herein, a three-dimensional (3D) flexible N, B co-doped carbon foam (NBC) is developed, enabling efficient polysulfides confinement. N, B co-doping is employed to overcome the conflict between heteroatom doping and stability of carbon lattice, because one B and one N atoms are isoelectronic to two C atoms. B atoms in such a carbon structure possess positive charge which can interact with Sn2− anions in forming Sn2− … B while N atoms form negative charge which construct a strong-couple interaction with Li+ cations in forming N⋯Li2Sn. Moreover, the fabrication approach of corresponding flexible 3D carbon form is extremely facile derived from the self-gelation of agar. When used as the host for S, such a 3D carbon foam provides a continuous conductive structure, accommodates the volume change during long-term cycling and serves as a barrier for polysulfides dissolution. As a result, cycling performance of high sulfur loading (5.8 mg cm−2) NBC-S electrode exhibits high areal capacity of 5.6 mA h cm−2 (965 mA h g−1) with a very small capacity decay of 0.03% per cycle over 350 cycles at 0.2 C.

Chemical activation has been widely used to synthesize porous carbon materials due to its promising application on energy storages. To ensure the sufficient activation, heavily usage of activation agent is necessary, which is unsafe and uneconomical for massive production. Here a sol-gel assisted chemical activation strategy was proposed to synthesize nitrogen doped porous carbon material. The sol-gel process ensured the activation agent uniformly mixed with carbon precursors, which achieved sufficient activation at a quietly low consumption of activation agent. As synthesized carbon material possesses high specific surface area (2140 m2/g) and N, O content (5.42 at.% and 11.29 at.%). Electrochemical characterization shows that the material delivers a capacitance of 334 F/g in 1 M H2SO4 electrolyte. The sol-gel assisted chemical activation is a promising strategy to synthesize low-cost nitrogen doped porous carbon materials.

Black TiO2-x attracts enormous attention due to its large solar absorption and improved conductivity. In this work, a novel structure of TiO2-x with conductive TiO layer, performing full-spectrum absorption, was synthesized in one step by the unforeseen dismutation reaction of titanium sub-oxides (Tin O2n-1 ) in ammonium halide atmosphere. For this new reaction, a possible mechanism of decomposition-etching-disproportionation-rehydrolysis process was proposed. The vital intermediate reactant TiCl4 , which verifies the assumption, has been captured in the form of (NH4 )2 TiCl6 , especially where Ti2 O3 is the reactant. Furthermore, this work not only can nominate TiO as an alternative for noble metals or carbon materials in the aim to improve the electron conductivity and solar absorption of black TiO2-x , which are important in electrochemistry and optoelectronics fields, but also can be a new route to synthesize special structures for other multivalent transition metals.

In this study, in situ synthesis of carbon-coated MoC1–x nanodots anchored on nitrogen-doped carbon (MoC1–x@C) for lithium storage is reported. The obtained MoC1–x@C hybrids exhibit intriguing stru...

Exploring novel electrocatalysts with prominent performance is highly demanded for electrochemical hydrogen evolution. As one family member of layered transition-metal dichalcogenides (TMDs), metal...

Rechargeable magnesium (Mg) and calcium (Ca) metal batteries (RMBs and RCBs) are promising alternatives to lithium (Li)-ion batteries due to their significantly higher crustal abundance and energy density. However, RMBs and RCBs are still plagued by high overpotentials associated with parasitic reactions and sluggish kinetics resulting from strong electrostatic interaction with the solvation sheath and cathode hosts. Here we significantly reduce the overpotentials associated with the interfacial charge transfer through reorganization of the methoxyethyl amine-based chelants in the first solvation sheath of Mg2+, enabling stable and highly reversible cycling of Mg||Mg0.15MnO2 full cell with energy density of 412 Wh kg-1 and Ca||Mg0.15MnO2 full cell with energy density of 471 Wh kg-1. The barrier for solvation sheath reorganization can be tuned by molecular structure of the chelants and the design principle is generally applicable in a variety of ether solvents, thus providing a highly versatile electrolyte design strategy for divalent metal batteries.

Aqueous Zn batteries are promising energy storage devices for large-scale energy-storage due to low cost and high energy density. However, their lifespan is limited by the water decomposition and Zn dendrite growth. Here, we suppress water reduction and Zn dendrite growth in dilute aqueous electrolyte by adding dimethyl sulfoxide (DMSO) into ZnCl2-H2O, in which DMSO replaces the H2O in Zn2+ solvation sheath due to a higher Gutmann donor number (29.8) of DMSO than that (18) of H2O. The preferential solvation of DMSO with Zn2+ and strong H2O-DMSO interaction inhibit the decomposition of solvated H2O. In addition, the decomposition of solvated DMSO forms Zn12(SO4)3Cl3(OH)15·5H2O, ZnSO3, and ZnS enriched-solid electrolyte interphase (SEI) preventing Zn dendrite and further suppressing water decomposition. The ZnCl2-H2O-DMSO electrolyte enables Zn anodes in Zn||Ti half-cell to achieve a high average Coulombic efficiency of 99.5% for 400 cycles (400 h), and the Zn||MnO2 full cell with a low capacity ratio of Zn:MnO2 at 2:1 to deliver a high energy density of 212 Wh/kg (based on both cathode and anode) and maitain 95.3% of the capacity over 500 cycles at 8 C.

Nitrogen-rich carbon materials attract great attention because of their admirable performance in energy storage and electrocatalysis. However, their conductivity and nitrogen content are somehow contradictory because good conductivity requires high-temperature heat treatment, which decomposes most of the nitrogen species. Herein, we propose a facile method to solve this problem by introducing boron (B) to fix the nitrogen in a three-dimensional (3D) carbon material even at 1000 °C. Besides, this N-rich carbon material has a high content of pyrrolic nitrogen due to the selective stabilization of B, which is favorable in electrochemical reactions. Density functional theory (DFT) investigation demonstrates that B reduces the energy level of neighboring N species (especially pyrrolic nitrogen) in the graphene layer, making it difficult to escape. Thus, this carbon material simultaneously, achieves high conductivity (30 S cm-1) and nitrogen content (7.80 atom %), thus showing an outstanding capacitance of 412 F g-1 and excellent rate capability.

High voltage aqueous Li-ion batteries have the potential for sustainable large-scale energy storage due to their intrinsic advantages of safety, low cost, as well as environmental friendliness. “Water-in-salt” electrolytes have significantly enhanced the energy density of aqueous Li-ion batteries by extending the aqueous electrolyte stability window to 3.0 V. However, the cathodic limit and salt concentration need to be reduced, enabling to operate low cost LiMn2O4/Li4Ti5O12 cells. In addition, gravimetric energy density of LiMn2O4/Li4Ti5O12, self-discharge rate, and operation temperature range remain rarely studied. This perspective aims to briefly summarize the opportunity and challenges of aqueous batteries for practical applications.

Black materials are the key to convert solar light to thermal energy, but it is not easy to economically achieve full solar-spectrum light absorption and maximally harvest solar energy. Herein, we develop a “popcorn” approach based on a space-confined pyrolysis of copper carbodiimide to synthesis Cu nanodot-embedded N-doped graphene urchins. In situ formed Cu nanodots are rigidly fixed and spatially scaffolded in the graphene matrix, achieving nearly full-spectrum solar light absorption (99%) over a wide spectral range (300–1800 nm). Such a highly efficient solar harvest is endowed by an intensively hybridized localized surface plasmon resonance and stabilized by graphene matrix. When applied in solar desalination, the N-doped graphene urchins provide structural interconnectivity and freeway for water transports and enable the as-formed plasmonic absorber to naturally self-float on water. By localizing the absorbed energy at the interfaces, efficient (~ 82%) and stable desalination is ultimately achieved under a simulated solar light. Practically, a solar desalination system of the plasmonic absorber can produce fresh water with a rate of ~ 5 L m−2 day−1 under solar irradiation.

Titania with intrinsic safety (without lithium deposition) has met the safety requirement for high-power batteries, however, its poor rate capability due to sluggish ion diffusion coefficients remains as a challenge. Here mesoporous structure titania with a fast ion-conducting surface layer through lithiation can achieve capacitive lithium storage: 220 mA h g−1 at 1 C, 114 mA h g−1 at 50 C, 93 mA h g−1 at 100 C. The improvement in rate performance can be attributed to two factors: The resulting lithiated titania shows over 5 orders of magnitude improvement of conductivity (from 0.001 to 198.20 μS cm −1) induced by the presence of bulk Ti3+ , enabling an ultra-fast conduction path for electrons; The lithiated surface layer is favorable to faster lithium ion transport, addressing the limited lithium diffusion between the electrolyte and the active electrode materials. This new route may offer a general approach towards lithium batteries with capacitor-like rate performance.

To achieve large-scale preparation of high-performance carbon materials for electrochemical energy storage with a simple and cost-effective method remains a challenge. Here, we report a novel approach to synthesize hierarchical porous carbon with a low melting point metal tin (Sn) as pore forming agent. An aqueous processed tin chloride-polyethylene glycol (SnCl2-PEG) gel is used as precursor to form Sn/Carbon (Sn/C) composites with homogeneously distributed ultrafine Sn particles (

Selections of metallic cathode materials and modulations of metal–sulfur bonding strength are crucial for sulfur immobilization in development of high-performance lithium–sulfur (Li–S) batteries with low cost. By combining theoretical calculations and experiments, herein we reveal the relationship between intrinsic electronic structure and metal–S bonding strength, which links to energy density and durability of Li–S batteries. Through first-principles calculations, we simulate sulfur clusters (S1, S2, S4, and S8) immobilization on metal (Cu, Ni, and Sn) slab surfaces with and without graphene substrate. For sulfur clusters, the metal–Sx (x = 1, 2, 4, and 8) bonding strength is in the sequence of Ni > Cu > Sn without graphene substrate. Nevertheless, the sequence changes (Ni > Sn > Cu) in the presence of graphene substrate due to different amounts of charge transfer between these metal clusters and graphene. Guided by these theoretical results, metal (Cu, Ni, Sn)/graphene (G) composites are synthesized an...

Nitrogen-doped hollow carbon spheres with a well-defined shape, uniform diameter, and high doping concentration (11 at%) are synthesized via space-confined thermal decomposition of a single source precursor zinc carbodiimide, which can serve as both carbon and nitrogen sources and also a self-template.

The mixed-metal sulfide compound with the formula Ba2Fe0.6V1.4S6 was successfully synthesized via solid-state reaction. Ba2Fe0.6V1.4S6 has a quasi-one-dimensional structure and crystallizes in the hexagonal space group P63/mmc. The structure is composed of face-sharing anion octahedron [MS6]8– (M = V or Fe) units to construct infinite chains along the c axis, in which the Fe atoms randomly occupy the V sites. The Ba2+ ions reside between adjacent chains. Magnetic susceptibility measurements reveal a transition between paramagnetism and ferromagnetism around 25 K. The small polaron hopping (SPH) conduction behavior has been observed in the higher temperature region (75–300 K), while in the lower temperature region (25–74 K), the resistivity features a variable range hopping mechanism (VRH). The analysis of density of states indicates that Fe-3dz2 and S-3p states mainly dominate the valence band maximum, while Fe-3dz2 states contribute significantly to the magnetic susceptibility.

One-dimensional TiO2 nanowire is the top-performing semiconductor among photoanodes for photoelectrochemical water splitting, but still limited to a fraction of the theoretically photocurrent because of modest charge transport and low charge separation properties. Here, we demonstrate high-crystallized nanowires of Nb-doped rutile TiO2 for significantly increasing electron carrier density through a convenient method. The optimized Nb-doped TiO2 nanowires (0.5 mol% in the Nb/Ti ratio) yield a high value of charge separation efficiency (ηsep) of 97.39% at 1.23 VRHE, which is about 3 times as much as that of pristine sample (33.61% at 1.23 VRHE). Moreover, the photoanode of Nb-doped TiO2 nanowires can achieve high charge transfer efficiency (ηtrans) (91.07% at 1.23 VRHE) without any oxygen evolution reaction catalysts. These results indicate that through appropriate amount of Nb doping can move the performance of TiO2 nanowires to their theoretical potential.

Ilmenite-type MTiO3 (M = Ni, Co, Fe) with high theoretical specific capacity, wide availability, and low cost is a potential anode material for lithium storage, but its poor cycling stability is fatal. Here, we propose a general material design strategy to encapsulate MTiO3 nanorods with in situ grown few-layer graphene through a facile plasma-enhanced CVD route for stable lithium storage. Under the reductive plasma-enhanced CVD atmosphere, partially reduced Ni served as a self-catalysis substrate for in situ graphene growth, resulting in the perfect encapsulation of NiTiO3 nanorods with few-layer graphene. The graphene coating helps to retain the electrical connectivity during cycling, which is beneficial for better cycling performance and rate capability. Stable cycling (500 cycles at 0.2 A g–1; 83% capacity retention) is achieved with the NiTiO3@graphene nanorods.

In this study, in situ synthesis of carbon-coated MoC

Black TiO