Rechargeable aqueous zinc-ion batteries are promising candidates for large-scale energy storage but are plagued by the lack of cathode materials with both excellent rate capability and adequate cycle life span. We overcome this barrier by designing a novel hierarchically porous structure of Zn-vanadium oxide material. This Zn0.3V2O5·1.5H2O cathode delivers a high specific capacity of 426 mA·h g−1 at 0.2 A g−1 and exhibits an unprecedented superlong-term cyclic stability with a capacity retention of 96% over 20,000 cycles at 10 A g−1. Its electrochemical mechanism is elucidated. The lattice contraction induced by zinc intercalation and the expansion caused by hydronium intercalation cancel each other and allow the lattice to remain constant during charge/discharge, favoring cyclic stability. The hierarchically porous structure provides abundant contact with electrolyte, shortens ion diffusion path, and provides cushion for relieving strain generated during electrochemical processes, facilitating both fast kinetics and long-term stability.

Lithium sulfide (Li2S) is a promising cathode material for Li-S batteries with high capacity (theoretically 1166 mAh g(-1)) and can be paired with nonlithium-metal anodes to avoid potential safety issues. However, the cycle life of coarse Li2S particles suffers from poor electronic conductivity and polysulfide shuttling. Here, we develop a flexible slurryless nano-Li2S/reduced graphene oxide cathode paper (nano-Li2S/rGO paper) by simple drop-coating. The Li2S/rGO paper can be directly used as a free-standing and binder-free cathode without metal substrate, which leads to significant weight savings. It shows excellent rate capability (up to 7 C) and cycle life in coin cell tests due to the high electron conductivity, flexibility, and strong solvent absorbency of rGO paper. The Li2S particles that precipitate out of the solvent on rGO have diameters 25-50 nm, which is in contrast to the 3-5 μm coarse Li2S particles without rGO.

Owing to the layered structure and high theoretical capacity, MoS2 has attracted more and more interest as a potential anode material for lithium-ion batteries. However, it suffers from rapid capacity decay and low rate capability. In this work, we introduce a novel hierarchical material consisting of ultrathin MoS2 nanosheets grown on the surface of an active carbon fiber (ACF) cloth fabricated by a facile morphogenetic process. The ACF cloth acts as both a template and a stabilizer. The obtained MoS2/ACF cloth composite possesses hierarchical porosity and an interconnected framework. Serving as a free-standing and binder-free anode, it shows high specific capacity and excellent reversibility. A discharge capacity as high as 971 mA h g(-1) is attained at a current density of 0.1 A g(-1), and the capacity fade is only 0.15% per cycle within 90 cycles. Even after 200 cycles at a high current density of 0.5 A g(-1), the composite still shows a capacity of 418 mA h g(-1). The superior electrochemical performance of MoS2/ACF can be attributed to its robust structure and to the synergistic effects of ultrathin MoS2 nanosheets and ACF. This single-component anode that we propose benefits from a simplified electrode preparation process. The morphogenetic strategy used for the material production is facile but effective, and can be extended to prepare other metal sulfides with elaborate textural characteristics.

A porous three-dimensional nitrogen-doped graphene (3D-NG) was introduced as an interconnected framework for sulfur in lithium-sulfur batteries. The 3D-NG-sulfur composite (3D-NGS) with a high sulfur content of 87.6 wt% was synthesized via a facile one-pot solution method and sulfur was well dispersed within it. The as-designed 3D-NGS composite exhibits excellent rate capability and cyclability.The discharge specific capacity is 792 mA h g À1 after 145 cycles at a current density of 600 mA g À1 and the capacity fading rate is 0.05% per cycle. Even at a high rate of 1500 mA g À1 , the composite still shows a good cycle performance with a capacity of 671 mA h g À1 after 200 cycles. The outstanding electrochemical performance can be attributed to the flexible porous 3D structure and N-doping in graphene. The flexible 3D-NG can provide a conductive framework for electron transport and alleviate the volume effect during cycling. N-doping can facilitate the penetration of Li ions across the graphene and restrain sulfur due to the strong chemical bonding between S and the nearby N atoms.

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There is great interest in utilization of silicon-containing nanostructures as anode materials for lithium-ion batteries but usually limited by manufacturing cost, their intrinsic low electric conductivity, and large volume changes during cycling. Here we present a facile process to fabricate graphene-wrapped silicon nanowires (GNS@Si NWs) directed by electrostatic self-assembly. The highly conductive and mechanical flexible graphene could partially accommodate the large volume change associated with the conversion reaction and also contributed to the enhanced electronic conductivity. The as-prepared GNS@Si NWs delivered a reversible capacity of 1648 mAh·g(-1) with an initial Coulombic efficiency as high as 80%. Moreover, capacity remained 1335 mAh·g(-1) after 80 cycles at a current of 200 mA·g(-1), showing significantly improved electrochemical performance in terms of rate capability and cycling performance.

Lithium-sulfur batteries are promising electrochemical devices for future energy conversion and storage.Its theoretical capacity is 1675 mA h g À1 , much higher than that of conventional lithium-ion batteries.However, it suffers from rapid capacity decay and low energy efficiency. In this work, we introduce a novel dual core-shell structured sulfur composite with multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy), MWCNTs@S@PPy, as a cathode material for Li-S batteries. The composite is synthesized via a facile one-pot method. In the structure, MWCNTs and PPy work as a combined conductive framework to provide access to Li + ingress and egress for reaction with sulfur, and to inhibit the diffusion of polysulfide out of the cathode, and hence reduce the capacity decay. Meanwhile, LiNO 3 additive is added into the electrolyte to improve the coulombic efficiency. The as-designed MWCNTs@S@PPy composite shows excellent rate capability and cyclability. The initial discharge specific capacity is as high as 1517 mA h g À1 , and remains at 917 mA h g À1 after 60 cycles at a current density of 200 mA g À1 . Even at a high current density of 1500 mA g À1 , the composite still shows a good cycle performance with a capacity of 560 mA h g À1 after 200 cycles.