Lei-Lei Lu

Free-Standing Copper Nanowire Network Current Collector for Improving Lithium Anode Performance

Lithium metal is one of the most attractive anode materials for next-generation lithium batteries due to its high specific capacity and low electrochemical potential. However, the poor cycling performance and serious safety hazards, caused by the growth of dendritic and mossy lithium, has long hindered the application of lithium metal based batteries. Herein, we reported a rational design of free-standing Cu nanowire (CuNW) network to suppress the growth of dendritic lithium via accommodating the lithium metal in three-dimensional (3D) nanostructures. We demonstrated that as high as 7.5 mA h cm(-2) of lithium can be plated into the free-standing copper nanowire (CuNW) current collector without the growth of dendritic lithium. The lithium metal anode based on the CuNW exhibited high Coulombic efficiency (average 98.6% during 200 cycles) and outstanding rate performance owing to the suppression of lithium dendrite growth and high conductivity of CuNW network. Our results demonstrate that the rational nanostructural design of current collector could be a promising strategy to improve the performance of lithium metal anode enabling its application in next-generation lithium-metal based batteries.

Scalable Template Synthesis of Resorcinol–Formaldehyde/Graphene Oxide Composite Aerogels with Tunable Densities and Mechanical Properties

Resorcinol-formaldehyde (RF) and graphene oxide (GO) aerogels have found a variety of applications owing to their excellent properties and remarkable flexibility. However, the macroscopic and controllable synthesis of their composite gels is still a great challenge. By using GO sheets as template skeletons and metal ions (Co(2+), Ni(2+), or Ca(2+)) as catalysts and linkers, the first low-temperature scalable strategy for the synthesis of a new kind of RF-GO composite gel with tunable densities and mechanical properties was developed. The aerogels can tolerate a strain as high as 80% and quickly recover their original morphology after the compression has been released. Owing to their high compressibility, the gels might find applications in various areas, for example, as adsorbents for the removal of dye pollutants and in oil-spill cleanup.

Low Cost Metal Carbide Nanocrystals as Binding and Electrocatalytic Sites for High Performance Li–S Batteries

Lithium sulfur (Li-S) batteries are considered as promising energy storage systems for the next generation of batteries due to their high theoretical energy densities and low cost. Much effort has been made to improve the practical energy densities and cycling stability of Li-S batteries via diverse designs of materials nanostructure. However, achieving simultaneously good rate capabilities and stable cycling of Li-S batteries is still challenging. Herein, we propose a strategy to utilize a dual effect of metal carbide nanoparticles decorated on carbon nanofibers (MC NPs-CNFs) to realize high rate performance, low hysteresis, and long cycling stability of Li-S batteries in one system. The adsorption experiments of lithium polysulfides (LiPS) to MC NPs and corresponding theoretical calculations demonstrate that LiPS are likely to be adsorbed and diffused on the surface of MC NPs because of their moderate chemical bonding. MC NPs turn out to have also an electrocatalytic role and accelerate electrochemical redox reactions of LiPS, as proven by cyclic voltammetry analysis. The fabricated Li-S batteries based on the W2C NPs-CNFs hybrid electrodes display not only high specific capacity of 1200 mAh/g at 0.2C but also excellent rate performance and cycling stability, for example, a model setup can be operated at 1C for 500 cycles maintaining a final specific capacity of 605 mAh/g with a degradation rate as low as 0.06%/cycle.

Prawn Shell Derived Chitin Nanofiber Membranes as Advanced Sustainable Separators for Li/Na-Ion Batteries

Separators, necessary components to isolate cathodes and anodes in Li/Na-ion batteries, are consumed in large amounts per year; thus, their sustainability is a concerning issue for renewable energy storage systems. However, the eco-efficient and environmentally friendly fabrication of separators with a high mechanical strength, excellent thermal stability, and good electrolyte wettability is still challenging. Herein, we reported the fabrication of a new type of separators for Li/Na-ion batteries through the self-assembly of eco-friendly chitin nanofibers derived from prawn shells. We demonstrated that the pore size in the chitin nanofiber membrane (CNM) separator can be tuned by adjusting the amount of pore generation agent (sodium dihydrogen citrate) in the self-assembly process of chitin nanofibers. By optimizing the pore size in CNM separators, the electrochemical performance of the LiFePO4/Li half-cell with a CNM separator is comparable to that with a commercialized polypropylene (PP) separator. More attractively, the CNM separator showed a much better performance in the LiFePO4/Li cell at 120 °C and Na3V2(PO4)3/Na cell than the PP separator. The proposed fabrication of separators by using natural raw materials will play a significant contribution to the sustainable development of renewable energy storage systems.

Large-Scale Syntheses of Zinc Sulfide⋅(Diethylenetriamine)0.5 Hybrids as Precursors for Sulfur Nanocomposite Cathodes

Nanostructured metal sulfide-amine hybrid materials have attracted attention because of their unique properties and versatility as precursors for functional inorganic nanomaterials. However, large-scale synthesis of metal sulfide-amine hybrid nanomaterials is limited by hydrothermal and solvothermal preparative reaction conditions; consequently, incorporation of such materials into functional nanomaterials is hindered. An amine molecule-assisted refluxing method was used to synthesize highly uniform zinc sulfide⋅(diethylenetriamine)0.5 (ZnS⋅(DETA)0.5 ) hybrid nanosheets and nanobelts in a large scale. The obtained ZnS⋅(DETA)0.5 hybrid nanomaterials can be used as efficient precursors to fabricate functional ZnS nanomaterials and carbon encapsulated sulfur (S@C) nanocomposite cathodes for Li-S batteries.

Wood‐Inspired High‐Performance Ultrathick Bulk Battery Electrodes

Ultrathick electrode design is a promising strategy to enhance the specific energy of Li-ion batteries (LIBs) without changing the underlying materials chemistry. However, the low Li-ion conductivity caused by ultralong Li-ion transport pathway in traditional random microstructured electrode heavily deteriorates the rate performance of ultrathick electrodes. Herein, inspired by the vertical microchannels in natural wood as the highway for water transport, the microstructures of wood are successfully duplicated into ultrathick bulk LiCoO2 (LCO) cathode via a sol-gel process to achieve the high areal capacity and excellent rate capability. The X-ray-based microtomography demonstrates that the uniform microchannels are built up throughout the whole wood-templated LCO cathode bringing in 1.5 times lower of tortuosity and ≈2 times higher of Li-ion conductivity compared to that of random structured LCO cathode. The fabricated wood-inspired LCO cathode delivers high areal capacity up to 22.7 mAh cm-2 (five times of the existing electrode) and achieves the dynamic stress test at such high areal capacity for the first time. The reported wood-inspired design will open a new avenue to adopt natural hierarchical structures to improve the performance of LIBs.

High Voltage Magnesium-ion Battery Enabled by Nanocluster Mg3Bi2 Alloy Anode in Noncorrosive Electrolyte

Currently, developing high voltage (beyond 2 V) rechargeable Mg-ion batteries still remains a great challenge owing to the limit of corrosive electrolyte and low compatibility of anode material. Here we report a facile one step solid state alloying route to synthesize nanoclustered Mg3Bi2 alloy as a high-performance anode to build up a 2 V Mg-ion battery using noncorrosive electrolyte. The fabricated nanoclustered Mg3Bi2 anode delivers a high reversible specific capacity (360 mAh g-1) with excellent stability (90.7% capacity retention over 200 cycles) and high Coulombic efficiency (average 98%) at 0.1 A g-1. The good performance is attributed to the stable nanostructures, which effectively accommodate the reversible Mg2+ ion insertion/deinsertion without losing electric contact among clusters. Significantly, the nanoclustered Mg3Bi2 anode can be coupled with high voltage cathode Prussian Blue to assemble a full cell using noncorrosive electrolyte, showing a stable cycling (88% capacity retention over 200 cycles at 0.2 A g-1) and good rate capability (103 mAh g-1 at 0.1 A g-1 and 58 mAh g-1 at 2 A g-1). The energy and power density of the as-fabricated full cell can reach up to 81 Wh kg-1 and 2850 W kg-1, respectively, which are both the highest values among the reported Mg-ion batteries using noncorrosive electrolytes. This study demonstrates a cost-effective route to fabricate stable and high voltage rechargeable Mg-ion battery potentially for grid-scale energy storage.