Minimized Volume Expansion in Hierarchical Porous Silicon upon Lithiation.

Silicon (Si) remains one of the most promising anode materials for next-generation lithium-ion batteries (LIBs). The key challenge for Si anodes is the huge volume change during lithiation-delithiation cycles that leads to electrode pulverization and rapid capacity fading. Here, we report a hierarchical porous Si (hp-Si) with a tailored porous structure [tunable primary pores (20-200 nm) and secondary nanopores (∼3-10 nm)] that can effectively minimize the volume expansion.

A Fluorinated Ether Electrolyte Enabled High Performance Prelithiated Graphite/Sulfur Batteries.

Lithium/sulfur (Li/S) batteries have attracted great attention as a promising energy storage technology, but so far their practical applications are greatly hindered by issues of polysulfide shuttling and unstable lithium/electrolyte interface. To address these issues, a feasible strategy is to construct a rechargeable prelithiated graphite/sulfur batteries. In this work, a fluorinated ether of bis(2,2,2-trifluoroethyl) ether (BTFE) was reported to blend with 1,3-dioxolane (DOL) for making a multifunctional electrolyte of 1.

Functional Organosulfide Electrolyte Promotes an Alternate Reaction Pathway to Achieve High Performance in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have recently received great attention because they promise to provide energy density far beyond current lithium ion batteries. Typically, Li-S batteries operate by conversion of sulfur to reversibly form different soluble lithium polysulfide intermediates and insoluble lithium sulfides through multistep redox reactions. Herein, we report a functional electrolyte system incorporating dimethyl disulfide as a co-solvent that enables a new electrochemical reduction pathway for sulfur cathodes.

Self-Templated Synthesis of Mesoporous Carbon from Carbon Tetrachloride Precursor for Supercapacitor Electrodes.

A high-surface-area mesoporous carbon material has been synthesized using a self-templating approach via reduction of carbon tetrachloride by sodium potassium alloy. The advantage is the reduction-generated salt templates can be easily removed with just water. The produced mesoporous carbon has a high surface area and a narrow pore size distribution.

Integrating Si nanoscale building blocks into micro-sized materials to enable practical applications in lithium-ion batteries.

This article highlights recent advances in micro-sized silicon anode materials composed of silicon nanoscale building blocks for lithium-ion batteries. These materials show great potential in practical applications since they combine good cycling stability, high rate performance, and high volumetric capacity. Different preparation methods are introduced and the features and performance of the resulting materials are discussed.

Advanced Sulfur Cathode Enabled by Highly Crumpled Nitrogen-Doped Graphene Sheets for High-Energy-Density Lithium-Sulfur Batteries.

Herein, we report a synthesis of highly crumpled nitrogen-doped graphene sheets with ultrahigh pore volume (5.4 cm(3)/g) via a simple thermally induced expansion strategy in absence of any templates. The wrinkled graphene sheets are interwoven rather than stacked, enabling rich nitrogen-containing active sites.

Advanced Sodium Ion Battery Anode Constructed via Chemical Bonding between Phosphorus, Carbon Nanotube, and Cross-Linked Polymer Binder.

Maintaining structural stability is a great challenge for high-capacity conversion electrodes with large volume change but is necessary for the development of high-energy-density, long-cycling batteries. Here, we report a stable phosphorus anode for sodium ion batteries by the synergistic use of chemically bonded phosphorus-carbon nanotube (P-CNT) hybrid and cross-linked polymer binder. The P-CNT hybrid was synthesized through ball-milling of red phosphorus and carboxylic group functionalized carbon nanotubes.

Polyanthraquinone as a Reliable Organic Electrode for Stable and Fast Lithium Storage.

In spite of recent progress, there is still a lack of reliable organic electrodes for Li storage with high comprehensive performance, especially in terms of long-term cycling stability. Herein, we report an ideal polymer electrode based on anthraquinone, namely, polyanthraquinone (PAQ), or specifically, poly(1,4-anthraquinone) (P14AQ) and poly(1,5-anthraquinone) (P15AQ). As a lithium-storage cathode, P14AQ showed exceptional performance, including reversible capacity almost equal to the theoretical value (260 mA h g(-1); >257 mA h g(-1) for AQ), a very small voltage gap between the charge and discharge curves (2.

Understanding the effect of a fluorinated ether on the performance of lithium-sulfur batteries.

A high performance Li-S battery with novel fluoroether-based electrolyte was reported. The fluorinated electrolyte prevents the polysulfide shuttling effect and improves the Coulombic efficiency and capacity retention of the Li-S battery. Reversible redox reaction of the sulfur electrode in the presence of fluoroether TTE was systematically investigated.

Strong lithium polysulfide chemisorption on electroactive sites of nitrogen-doped carbon composites for high-performance lithium-sulfur battery cathodes.

Despite the high theoretical capacity of lithium-sulfur batteries, their practical applications are severely hindered by a fast capacity decay, stemming from the dissolution and diffusion of lithium polysulfides in the electrolyte. A novel functional carbon composite (carbon-nanotube-interpenetrated mesoporous nitrogen-doped carbon spheres, MNCS/CNT), which can strongly adsorb lithium polysulfides, is now reported to act as a sulfur host. The nitrogen functional groups of this composite enable the effective trapping of lithium polysulfides on electroactive sites within the cathode, leading to a much improved electrochemical performance (1200 mAh g(-1) after 200 cycles).

Phosphorus-Graphene Nanosheet Hybrids as Lithium-Ion Anode with Exceptional High-Temperature Cycling Stability.

is reported as an anode material for lithium-ion batteries. Graphene nanosheets form a sea-like, highly electronically conductive matrix, where the island-like phosphorus particles are dispersed. Benefiting from this structure and properties of phosphorus, the hybrid delivers high initial capacity and exhibits promising retention at 60 °C.

Chemically bonded phosphorus/graphene hybrid as a high performance anode for sodium-ion batteries.

Room temperature sodium-ion batteries are of great interest for high-energy-density energy storage systems because of low-cost and natural abundance of sodium. Here, we report a novel phosphorus/graphene nanosheet hybrid as a high performance anode for sodium-ion batteries through facile ball milling of red phosphorus and graphene stacks. The graphene stacks are mechanically exfoliated to nanosheets that chemically bond with the surfaces of phosphorus particles.

Bis(2,2,2-trifluoroethyl) ether as an electrolyte co-solvent for mitigating self-discharge in lithium-sulfur batteries.

Lithium-sulfur batteries suffer from severe self-discharge because of polysulfide dissolution and side reaction. In this work, a novel electrolyte containing bis(2,2,2-trifluoroethyl) ether (BTFE) was used to mitigate self-discharge of Li-S cells having both low- and high-sulfur-loading sulfur cathodes. This electrolyte meaningfully decreased self-discharge at elevated temperature, though differences in behavior of cells with high- and low-sulfur-loading were also noted.

Porous spherical carbon/sulfur nanocomposites by aerosol-assisted synthesis: the effect of pore structure and morphology on their electrochemical performance as lithium/sulfur battery cathodes.

Porous spherical carbons (PSCs) with tunable pore structure (pore volume, pore size, and surface area) were prepared by an aerosol-assisted process. PSC/sulfur composites (PSC/S, S: ca.59 wt %) were then made and characterized as cathodes in lithium/sulfur batteries.

Bottom-up synthesis of high surface area mesoporous crystalline silicon and evaluation of its hydrogen evolution performance.

As an important material for many practical and research applications, porous silicon has attracted interest for decades. Conventional preparations suffer from high mass loss because of their etching nature. A few alternative routes have been reported, including magnesiothermic reduction; however, pre-formed porous precursors are still necessary, leading to complicated syntheses.

Mesoporous carbon-carbon nanotube-sulfur composite microspheres for high-areal-capacity lithium-sulfur battery cathodes.

Lithium-sulfur (Li-S) batteries offer theoretical energy density much higher than that of lithium-ion batteries, but their development faces significant challenges. Mesoporous carbon-sulfur composite microspheres are successfully synthesized by combining emulsion polymerization and the evaporation-induced self-assembly (EISA) process. Such materials not only exhibit high sulfur-specific capacity and excellent retention as Li-S cathodes but also afford much improved tap density, sulfur content, and areal capacity necessary for practical development of high-energy-density Li-S batteries.

Silicon core-hollow carbon shell nanocomposites with tunable buffer voids for high capacity anodes of lithium-ion batteries.

Silicon core-hollow carbon shell nanocomposites with controllable voids between silicon nanoparticles and hollow carbon shell were easily synthesized by a two-step coating method and exhibited different charge-discharge cyclability as anodes for lithium-ion batteries. The best capacity retention can be achieved with a void/Si volume ratio of approx. 3 due to its appropriate volume change tolerance and maintenance of good electrical contacts.

Polymer-graphene nanocomposites as ultrafast-charge and -discharge cathodes for rechargeable lithium batteries.

Electroactive polymers are a new generation of "green" cathode materials for rechargeable lithium batteries. We have developed nanocomposites combining graphene with two promising polymer cathode materials, poly(anthraquinonyl sulfide) and polyimide, to improve their high-rate performance. The polymer-graphene nanocomposites were synthesized through a simple in situ polymerization in the presence of graphene sheets.