High Young's Modulus Li6.4La3Zr1.4Ta0.6O12-Based Solid Electrolyte Interphase Regulating Lithium Deposition for Dendrite-Free Lithium Metal Anode.

Artificial solid electrolyte interphase (SEI) layers have been widely regarded as an effective protection for lithium (Li) metal anodes. In this work, an artificial SEI film consisting of dense Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles and polymerized styrene butadiene rubber is designed, which has good mechanical and chemical stability to effectively prevent Li anode corrosion by the electrolyte. The LLZTO-based SEI film can not only guide Li to uniformly deposit at the interface but also accelerate the electrochemical reaction kinetics due to its high Li+ conductivity. In particular, the high Young's modulus of the LLZTO-based SEI will regulate e- distribution in the continuous Li plating/stripping process and achieve uniform deposition of Li. As a consequence, the Li anode with LLZTO-based SEI (Li@LLZTO) enables symmetric cells to demonstrate a stable overpotential of 25 mV for 600 h at a current density of 1 mA cm-2 for 1 mA h cm-2. The Li@LLZTO||LFP (LiFePO4) full cell exhibits a capacity of 106 mA h g-1 after 800 cycles at 5 C with retention as high as 90%. Our strategy here suggests that the artificial SEI with high Young's modulus effectively inhibits the formation of Li dendrites and provides some guidance for the design of higher performance Li metal batteries.

Hydrogen Bonding Induced Confinement Effect between Ultrafine Nanowires and Polymer Chains for Low-Energy-Barrier Ion Transport in Composite Electrolytes.

Achieving low-energy-barrier lithium ion transport is a fundamental issue for composite solid-state electrolytes (CSEs) in all-solid-state lithium metal batteries (ASSLMBs). In this work, a hydrogen bonding induced confinement strategy was proposed to construct confined template channels for low-energy-barrier lithium ion continuous transport. Specifically, the ultrafine boehmite nanowires (BNWs) with 3.7 nm diameter were synthesized and superiorly dispersed in a polymer matrix to form a flexible CSE. The ultrafine BNWs with large specific surface areas and abundant oxygen vacancies assist the dissociation of lithium salts and confine the conformation of polymer chain segments by hydrogen bonding between the BNWs and the polymer matrix, thus forming a polymer/ultrafine nanowire intertwined structure as template channels for dissociated lithium ions continuous transport. As a result, the as-prepared electrolytes displayed a satisfactory ionic conductivity of 0.714 mS cm-1 and low energy barrier (16.30 kJ mol-1), and the assembled ASSLMB delivered excellent specific capacity retention (92.8%) after 500 cycles. This work demonstrates a promising way to design CSEs with high ionic conductivity for high-performance ASSLMBs.

Bifunctional Separator with Ultra-Lightweight MnO2 Coating for Highly Stable Lithium-Sulfur Batteries.

The severe shuttling behavior in the discharging-charging process largely hampers the commercialization of lithium-sulfur (Li-S) batteries. Herein, we design a bifunctional separator with an ultra-lightweight MnO2 coating to establish strong chemical adsorption barriers for shuttling effect alleviation. The double-sided polar MnO2 layers not only trap the lithium polysulfides through extraordinary chemical bonding but also ensure the uniform Li+ flux on the lithium anode and inhibit the side reaction, resulting in homogeneous plating and stripping to avoid corrosion of the Li anode. Consequently, the assembled Li-S battery with the MnO2-modified separator retains a capacity of 665 mA h g-1 at 1 C after 1000 cycles at the areal sulfur loading of 2.5 mg cm-2, corresponding to only 0.028% capacity decay per cycle. Notably, the areal loading of ultra-lightweight MnO2 coating is as low as 0.007 mg cm-2, facilitating the achievement of a high energy density of Li-S batteries. This work reveals that the polar metal oxide-modified separator can effectively inhibit the shuttle effect and protect the Li anode for high-performance Li-S batteries.

Adsorption-Catalysis-Conversion of Polysulfides in Sandwiched Ultrathin Ni(OH)2 -PANI for Stable Lithium-Sulfur Batteries.

Strong adsorption and catalysis for lithium polysulfides (LiPSs) are critical toward the electrochemical stability of Li-S batteries. Herein, a hollow sandwiched nanoparticle is put forward to enhance the adsorption-catalysis-conversion dynamic of sulfur species. The outer ultrathin Ni(OH)2 nanosheets not only confine LiPSs via both physical encapsulation and chemical adsorption, but also promote redox kinetics and accelerate the conversion of sulfur species, which is revealed by experiments and theoretical calculations. Meanwhile, the inner hollow polyaniline soft core provides a strong chemical bonding to LiPSs after vulcanization, which can chemically adsorpt LiPSs, and synergistically confine the shuttle effect. Moreover, the Ni(OH)2 nanosheets with a large specific area can enhance the wettability of electrolyte, and the flexible hollow sandwiched structure can accommodate the volume expansion, promoting sulfur utilization and structural stability. The obtained cathode exhibits excellent electrochemical performance with an initial discharge capacity of 1173 mAh g-1 and a small capacity decay of 0.08% per cycle even after 500 cycles at 0.2 C, among the best results of Ni(OH)2 -based materials for Li-S batteries. It is believed that the combination of adsorption-catalysis-conversion will shed a light on the development of cathode materials for stable Li-S batteries.

Alkoxide hydrolysis in-situ constructing robust trimanganese tetraoxide/graphene composite for high-performance lithium storage.

Herein we develop a novel and effective alkoxide hydrolysis approach to in-situ construct the trimanganese tetraoxide (Mn3O4)/graphene nanostructured composite as high-performance anode material for lithium-ion batteries (LIBs). This is the first report on the synthesis of Mn3O4/graphene composite via a facile hydrolysis of the manganese alkoxide (Mn-alkoxide)/graphene precursor. Before hydrolysis, two dimensional (2D) Mn-alkoxide nanoplates are closely adhered to 2D graphene nanosheets via Mn-O chemical bonding. After hydrolysis, the Mn-alkoxide in-situ converts to Mn3O4, while the Mn-O bond is preserved. This leads to a robust Mn3O4/graphene hybrid architecture with 15 nm Mn3O4 nanocrystals homogeneously anchoring on graphene nanosheets. This not only prevents the Mn3O4 nanocrystals agglomeration but also inversely mitigates the graphene nanosheets restacking. Moreover, the flexible and conductive graphene nanosheets can accommodate the volume change. This maintains the structural and electrical integrity of the Mn3O4/graphene electrode during the cycling process. As a result, the Mn3O4/graphene composite displays superior lithium storage performance with high reversible capacity (741 mAh g-1 at 100 mA g-1), excellent rate capability (403 mAh g-1 at 1000 mA g-1) and long cycle life (527 mAg g-1 after 300 cycles at 500 mA g-1). The electrochemical performance highlights the importance of rational design nanocrystals anchoring on graphene nanosheets for high-performance LIBs application.

Melamine-based polymer networks enabled N, O, S Co-doped defect-rich hierarchically porous carbon nanobelts for stable and long-cycle Li-ion and Li-Se batteries.

Li-Se battery is a promising energy storage candidate owing to its high theoretical volumetric capacity and safe operating condition. In this work, for the first time, we report using the whole organic Melamine-based porous polymer networks (MPNs) as a precursor to synthesize a N, O, S co-doped hierarchically porous carbon nanobelts (HPCNBs) for both Li-ion and Li-Se battery. The N, O, S co-doping resulting in the defect-rich HPCNBs provides fast transport channels for electrolyte, electrons and ions, but also effectively relieve volume change. When used for Li-ion battery, it exhibits an advanced lithium storage performance with a capacity of 345 mAh g-1 at 500 mA g-1 after 150 cycles and a superior rate capacity of 281 mAh g-1 even at 2000 mA g-1. Further density function theory calculations reveal that the carbon atoms adjacent to the doping sites are electron-rich and more effective to anchor active species in Li-Se battery. With the hierarchically porous channels and the strong dual physical-chemical confinement for Li2Se, the Se@ HPCNBs composite delivers an ultra-stable cycle performance even at 2 C after 1000 cycles. Our work here suggests that introduce of heteroatoms and defects in graphite-like anodes is an effective way to improve the electrochemical performance.

Active faceted Cu2O hollow nanospheres for unprecedented adsorption and visible-light degradation of pollutants.

We report the well-designed active {1 1 0} and {1 1 1} faceted Cu2O hollow nanospheres (Cu2O-HNs) for the quick removal of the high concentration pollutants in water. For the first time, these Cu2O-HNs combine the advantages of the active facets, hollow structure and nanostructures. The abundance of dangling Cu atoms in two active facets results in positively charged surface to effectively react with the negatively charged pollutants. The hollow structure provides the opportunity to take full use of these active sites. Consequently, the active faceted Cu2O-HNs demonstrate excellent adsorption and photodegradation capacities for high concentrated anionic dyes. The smallest Cu2O-HNs (~100 nm) can adsorb ~90% of methyl blue (MB) (100 mg L-1) in 10 min and degrade ~92% of MB (100 mg L-1) in 10 min under visible-light. In particular, a film consisting of the smallest Cu2O-HNs can quickly remove high concentrated organic dyes and be reused after solar light irradiation for 10 min in air, showing the promising practical application for the removal of organic pollutants.

In-Situ Growing Mesoporous CuO/O-Doped g-C3N4 Nanospheres for Highly Enhanced Lithium Storage.

The development of lithium-ion batteries using transition metal oxides has recently become more attractive, due to their higher specific capacities, better rate capability, and high energy densities. Herein, the in situ growth of advanced mesoporous CuO/O-doped g-C3N4 nanospheres is carried out in a two step hydrothermal process at 180 °C and annealing in air at 300 °C. When used as an anode material, the CuO/O-doped g-C3N4 nanospheres achieve a high reversible discharge specific capacity of 738 mAhg-1 and a capacity retention of ∼75.3% after 100 cycles at a current density 100 mAg-1 compared with the pure CuO (412 mAhg-1, 47%) and O-doped g-C3N4 (66 mAhg-1, 53%). Even at high current density 1 Ag-1, they exhibit a reversible discharge specific capacity of 503 mAhg-1 and capacity retention ∼80% over 500 cycles. The excellent electrochemical performance of the CuO/O-doped g-C3N4 nanocomposite is attributed to the following factors: (I) the in situ growing CuO/O-doped g-C3N4 avoids CuO nanoparticle aggregation, leading to the improved lithium ion transfer and electrolyte penetration inside the CuO/O-doped g-C3N4 anode, thus promoting the utilization of CuO; (II) the porous structure provides efficient space for Li+ transfer during the insertion/extraction process to avoid large volume changes; (III) the O-doping g-C3N4 decreases its band gap, ensuring the increased electrical conductivity of CuO/O-doped g-C3N4; and (IV) the strong interaction between CuO and O-doped g-C3N4 ensures the stability of the structure during cycling.