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Sulfur/highly porous carbon (HPC) composites were synthesized by thermally treating a mixture of sublimed sulfur and HPC. The microstructure of the HPC and the composite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area. The specific surface area of HPC reaches up to 1472.9 m 2 /g, which is sharply reduced to 24.4 m 2 /g in the sulfur/HPC composite with 57 wt % sulfur. The electrochemical performance of the composites as cathode materials in organic electrolytes was studied by the galvanostatic method and cyclic voltammetry. The sulfur/HPC composite with 57 wt % sulfur delivers the initial high specific capacity up to 1155 mAh/g and a stable capacity of 745 mAh/g after 84 cycles at the current density of 40 mA/g. In addition, it is demonstrated that the excellent cycling stability of the sulfur/HPC composite can be obtained at different current densities. On the basis of the analysis of the microstructure and electrochemical performance, it is confirmed that HPC can effectively prevent the shuttle behavior of the lithium/sulfur battery.

Long-term stability and high-rate capability have been the major challenges of sodium-ion batteries. Layered electroactive materials with mechanically robust, chemically stable, electrically and ironically conductive networks can effectively address these issues. Herein we have successfully directed carbon nanofibers to vertically penetrate through graphene sheets, constructing robust carbon nanofiber interpenetrated graphene architecture. Molybdenum disulfide nanoflakes are then grown in situ alongside the entire framework, yielding molybdenum disulfide@carbon nanofiber interpenetrated graphene structure. In such a design, carbon nanofibers prevent the restacking of graphene sheets and provide ample space between graphene sheets, enabling a strong structure that maintains exceptional mechanical integrity and excellent electrical conductivity. The as-prepared sodium ion battery delivers outstanding electrochemical performance and ultrahigh stability, achieving a remarkable specific capacity of 598 mAh g −1 , long-term cycling stability up to 1000 cycles, and an excellent rate performance even at a high current density up to 10 A g −1 .

Conductive confinement of sulfur and polysulfide via carbonaceous blocking layers can simultaneously address the low conductivity, volume expansion of sulfur during charge/discharge process and polysulfides shuttling effect in lithium-sulfur (Li-S) batteries. Herein, conductive and porous nitrogen and phosphorus dual doped graphene (p-NP-G) blocking layer is prepared via a thermal annealing and subsequent hydrothermal reaction route. The doping levels of N and P in p-NP-G measured by the X-ray photoelectron spectroscopy are ca. 4.38% and ca. 1.93 %, respectively. The dual doped blocking layer exhibits higher conductivity than N or P single doped blocking layer. More importantly, the density function theory (DFT) calculation demonstrates that P atoms and -P-O groups in the p-NP-G layer offer stronger adsorption to polysulfides than the N species. The electrochemical evaluation results illustrate that the p-NP-G blocking layer could deliver superior initial capacity (1158.3 mA h/g at the current density of 1 C), excellent rate capability (633.7 mA h/g at 2 C), and satisfactory cycling stability (ca. 0.09% capacity decay per cycle), which are better than the N or P single doped graphene. This work suggests that this synergetic combination of conductive and adsorptive confinement strategies induced by the multi-heteroatoms doping scheme is a promising approach for developing high performance Li-S batteries.

Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur (Li-S) batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur (BC-S) nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA·h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA·h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency (≥95%). This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.

Blue hydrogenated rutile TiO 2 nanoparticles (blue TiO 2 ) are prepared by treating white rutile via an enhanced hydrogenation process (i.e., high pressure and temperature). The materials characterization results demonstrate that the hydrogenation process leads to the increase in the unit cell volume and decrease in the size compared with the untreated white TiO 2 . The electrochemical impedance spectra analyses and theoretical energy calculations using density functional theory (DFT) suggest that the hydrogenation process not only improves electronic conductivity due to the formation of oxygen vacancy in the hydrogenation process but also dramatically augments lithium-ion mass transport within the crystalline lattice due to the introduction of oxygen vacancy and crystalline dislocation. Because of these characteristics resulting from the hydrogenation process, the blue TiO 2 based lithium ion batteries (LIBs) possess significantly higher energy capacity and better rate performance than the white TiO 2 based LIBs. In particular, at the rate of 0.1 and 5 C (1 C = 336 mAh g −1 ), the discharge capacities of the blue rutile are maintained at ca.179.8 and 129.2 mAh g −1 , while the capacities of the white TiO 2 are just ca. 119.6 and 55.5 mAh g −1 , respectively.

Although lithium (Li)-ion batteries have achieved great success in commercialization for sustainable and clean energy applications including portable electronics, electric transportation, and grid-scale energy storage, existing battery systems of graphitebased anodes and transition metal oxide-based cathodes hardly meet the increasing requirements for higher energy and power densities. [1][2][3][4] Li metal has a high theoretical capacity Metallic lithium (Li) is a promising anode for next-generation high-energydensity batteries, but its applications are still hampered due to the limited charging/discharging rate and poor cycling performance. Here, a hierarchical 3D porous architecture is designed with a binary network of continuous silver nanowires assembled on an interconnected 3D graphene skeleton as the host for Li-metal composite anodes, which offers a significant boost in both charging/discharging rates and long-term cycling performance for Li-metal batteries. This unique hierarchical binary network structure in conjunction with optimized material combination provides ultrafast, continuous, and smooth electron transportation channel and non-nucleation barrier sites to direct and confine Li deposition. It also offers outstanding mechanical strength and toughness to support massive Li deposition and buffer the internal stress fluctuations during long-term repeated Li stripping/plating thereby minimizing fundamental issues of dendrite formation and volume change even under ultrafast charging/discharging rates. As a result, the composite anode using this hierarchical host can work smoothly at an unprecedented high current density of 40 mA cm -2 over 1000 plating/stripping cycles with low overpotential (<120 mV) in symmetric cells. The as-constructed full cell, paired with LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode, also exhibits excellent rate capability and high-rate cycling stability.(3860 mAh g −1 ) and low electrochemical potential (−3.04 V vs the standard hydrogen electrode) and is thus perceived as an ideal anode for next-generation rechargeable batteries-especially for Li-sulfur and Li-oxygen battery systems. [5][6][7][8] However, the use of a Li-metal anode in advanced battery systems for stable and ultrafast charging/discharging is severely restricted by safety and cyclability concerns caused by dendritic Li formation, infinite volume change, and instability of solid electrolyte interphase (SEI). This has limited the practical use of Li-metal batteries for many decades. [9][10][11][12][13] Several strategies focused on constructing stable and uniform SEI layer on Li anode have been explored to tolerate the huge volume change and suppress the formation of dendritic Li. Examples include optimizing the electrolyte contents, modifying he Li anode surface, and developing artificial coatings on the anode surface. [10,[13][14][15][16] Despite the great success achieved on the rational design of SEI layer, the nature of Li dendrite formation arising from inhomogeneous Li-ion flux distribution on planar Li foil or copp...

Lithium metal is among the most promising anode materials for high-energy batteries due to its high theoretical capacity and lowest electrochemical potential. However, dendrite formation is a major challenge, which can result in fire and explosion of the batteries. Herein, we report on hexadecyl trimethylammonium chloride (CTAC) as an electrolyte additive that can suppress the growth of lithium dendrites by lithiophobic repulsion mechanisms. During the lithium plating process, cationic surfactant molecules can aggregate around protuberances via electrostatic attraction, forming a nonpolar lithiophobic protective outer layer, which drives the deposition of lithium ions to adjacent regions to produce dendrite-free uniform Li deposits. Thus, an excellent cycle of 300 h at 1.0 mA cm–2 and rate performance up to 4 mA cm–2 are available safely in symmetric Li|Li cells. In particular, significantly enhanced cycle and rate performance were achieved when the electrolyte with CTAC additives was used in lithium–sulfur and Li|LiNi0.5Co0.2Mn0.3O2 full cells. The effects of carbon chains, anions of surfactant, and electrostatic repulsion on the deposition of lithium anodes are reported. This work advances research in inhibiting Li dendrite growth with a new electrolyte additive based on cationic surfactants.