A review on anode materials for lithium/sodium-ion batteries

Since lithium-ion batteries(LIBs) have been substantially researched in recent years, they now possess exceptional energy and power densities, making them the most suited energy storage technology for use in developed and developing industries like stationary storage and electric cars, etc. Concerns about the cost and availability of lithium have prompted research into alternatives, such as sodium-ion batteries(SIBs), which use sodium instead of lithium as the charge carrier. This is especially relevant for stationary applications, where the size and weight of battery are less important. The working efficiency and capacity of these batteries are mainly dependent on the anode, cathode, and electrolyte. The anode,which is one of these components, is by far the most important part of the rechargeable battery.Because of its characteristics and its structure, the anode has a tremendous impact on the overall performance of the battery as a whole. Keeping the above in view, in this review we critically reviewed the different types of anodes and their performances studied to date in LIBs and SIBs. The review article is divided into three main sections, namely:(i) intercalation reaction-based anode materials;(ii) alloying reaction-based anode materials;and(iii) conversion reaction-based anode materials, which are further classified into a number of subsections based on the type of material used. In each main section, we have discussed the merits and challenges faced by their particular system. Afterward, a brief summary of the review has been discussed. Finally, the road ahead for better application of Li/Na-ion batteries is discussed, which seems to mainly depend on exploring the innovative materials as anode and on the inoperando characterization of the existing materials for making them more capable in terms of application in rechargeable batteries.

Nitrogen-doped microporous graphite-enhanced copper plasmonic effect for solar evaporation

Water scarcity is a global challenge,and solar evaporation technology offers a promising and eco-friendly solution for freshwater production.Photothermal conversion materials(PCMs)are crucial for solar evaporation.Improving photothermal conversion efficiency and reducing water evaporation enthalpy are the two key strategies for the designing of PCMs.The desired PCMs that combine both of these properties remain a challenging task,even with the latest advancements in the field.Herein,we developed copper nanoparticles(NPs)with different conjugated nitrogen-doped microporous carbon coatings(Cu@C–N)as PCMs.The microporous carbon enveloping layer provides a highly efficient pathway for water transport and a nanoconfined environment that protects Cu NPs and facilitates the evaporation of water clusters,reducing the enthalpy of water evaporation.Meanwhile,the conjugated nitrogen nodes form strong metal-organic coordination bonds with the surface of copper NPs,acting as an energy bridge to achieve rapid energy transfer and provide high solar-to-vapor conversion efficiency.The Cu@C–N exhibited up to 89.4%solar-to-vapor conversion efficiency and an evaporation rate of 1.94 kgm^(−2) h^(−1) under one sun irradiation,outperforming conventional PCMs,including carbon-based materials and semiconductor materials.These findings offer an efficient design scheme for high-performance PCMs essential for solar evaporators to address global water scarcity.

Control of interfacial reaction and defect formation in Gd/Bi_(2)Te_(2.7)Se_(0.3) composites with excellent thermoelectric and magnetocaloric properties

The method to combine thermoelectric(TE)and magnetocaloric(MC)cooling techniques lies in developing a new material that simultaneously possesses a large TE and good MC cooling performance.In this work,using n-type Bi_(2)Te_(2.7)Se_(0.3)(BTS)as the TE base material and Gd as the second-phase MC material,Gd/BTS composites were prepared by the spark plasma sintering method.In the composites,interfacial reaction between Gd and BTS was identified,resulting in the formation of Gd Te,which has a large impact on the electron concentration through the adjustment of defect concentration.The MC/TE composite containing 2.5 wt%Gd exhibited a ZT value of 0.6 at 300 K,essentially retaining the original TE performance,while all the composites largely maintained the excellent MC performance of Gd.This work provides a potential pathway to achieving high performance in MC/TE composites.

Application of Piezoelectric Materials in a Novel Linear Ultrasonic Motor based on Shear-induced Vibration Mode

A novel linear ultrasonic motor based on d15 effect of piezoelectric materials was presented. The design idea aimed at the direct utilization of the shear-induced vibration modes of piezoelectric material. Firstly, the inherent electromechanical coupling mechanism of piezoelectric material was investigated, and shear vibration modes of a piezoelectric shear block was specially designed. A driving point’s elliptical trajectory induced by shear vibration modes was discussed. Then a dynamic model for the piezoelectric shear stator was established with finite element（FE） method to conduct the parametric optimal design. Finally, a prototype based on d15 converse piezoelectric effect is manufactured, and the modal experiment of piezoelectric stator was conducted with laser doppler vibrometer. The experimental results show that the calculated shear-induced vibration modes can be excited completely, and the new linear ultrasonic motor reaches a speed 118 mm/s at noload, and maximal thrust 12.8 N.

Titanylphthalocyanine as hole transporting material for perovskite solar cells

Titanylphthalocyanine （TiOPc） as hole transporting material （HTM） was successfully synthesized by a simple process with low cost. Perovskite solar cells using the TiOPc as HTM were fabricated and characterized. TiOPc as HTM plays an important role in increasing the power conversion efficiency （PCE） by minimizing recombi- nation losses at the perovskite/Au interface because TiOPc as HTM can extract photogenerated holes from the perovskite and then transport quickly these charges to the back metal electrode. In the research, the β-TiOPc gives a higher PCE than α-TiOPc for the devices due to sufficient transfer dynamics, The β-TiOPc was applied in perovskite solar cells without clopping to afford an impressive PCE of 5.05% under AM 1.5G illumination at the thickness of 40 nm which is competitive with spiro-OMeTAD at the same condition. The present work suggests a guideline for optimizing the photovoltaic properties ofperovskite solar cells using the TiOPc as the HTM.

High-Energy Batteries:Beyond Lithium-Ion and Their Long Road to Commercialisation

Rechargeable batteries of high energy density and overall performance are becoming a critically important technology in the rapidly changing society of the twenty-first century.While lithium-ion batteries have so far been the dominant choice,numerous emerging applications call for higher capacity,better safety and lower costs while maintaining sufficient cyclability.The design space for potentially better alternatives is extremely large,with numerous new chemistries and architectures being simultaneously explored.These include other insertion ions(e.g.sodium and numerous multivalent ions),conversion electrode materials(e.g.silicon,metallic anodes,halides and chalcogens)and aqueous and solid electrolytes.However,each of these potential“beyond lithium-ion”alternatives faces numerous challenges that often lead to very poor cyclability,especially at the commercial cell level,while lithium-ion batteries continue to improve in performance and decrease in cost.This review examines fundamental principles to rationalise these numerous developments,and in each case,a brief overview is given on the advantages,advances,remaining challenges preventing cell-level implementation and the state-of-the-art of the solutions to these challenges.Finally,research and development results obtained in academia are compared to emerging commercial examples,as a commentary on the current and near-future viability of these“beyond lithium-ion”alternatives.

Revisiting the conversion reaction voltage and the reversibility of the CuF2 electrode in Li-ion batteries

Deviation between thermodynamic and experimental voltages is one of the key issues in Li-ion conversion-type electrode materials; the factor that affects this phenomenon has not been understood well in spite of its importance. In this work, we combine first principles calculations and electrochemical experiments with characterization tools to probe the conversion reaction voltage of transition metal difluorides MF2（M = Fe, Ni, and Cu）. We find that the conversion reaction voltage is heavily dependent on the size of the metal nanoparticles generated. The surface energy of metal nanoparticles appears to penalize the reaction energy, which results in a lower voltage compared to the thermodynamic voltage of a bulk-phase reaction. Furthermore, we develop a reversible CuF2 electrode coated with NiO. Electron energy loss spectroscopy （EELS） elemental maps demonstrate that the lithiation process mostly occurs in the area of high NiO content. This suggests that NiO can be considered a suitable artificial solid electrolyte interphase that prevents direct contact between Cu nanoparticles and the electrolyte. Thus, it alleviates Cu dissolution into the electrolyte and improves the reversibility of CuF2.

Recent progress in cobalt-based compounds as high-performance anode materials for lithium ion batteries

Despite carbonaceous materials are widely employed as commercial negative electrodes for lithium ion battery, an urge requirement for new electrode materials that meet the needs of high energy density, long cycle life, low cost and safety is still underway. A number of cobalt-based compounds（Co（OH）_2, Co_3O_4, CoN, CoS,CoP, NiCo_2O_4, etc.） have been developed over the past years as promising anode materials for lithium ion batteries（LIBs） due to their high theoretical capacity, rich redox reaction and adequate cyclability. The LIBs performances of the cobalt-based compounds have been significantly improved in recent years, and it is anticipated that these materials will become a tangible reality for practical applications in the near future. However, the different types of cobalt-based compounds will result in diverse electrochemical performance. This review briefly analyzes recent progress in this field, especially highlights the synthetic approaches and the prepared nanostructures of the diverse cobalt-based compounds and their corresponding performances in LIBs, including the storage capacity, rate capability, cycling stability and so on.

Rapid development in two-dimensional layered perovskite materials and their application in solar cells

Two-dimensional （2D） layered organic-inorganic hybrid perovskite （2D PVK） materials have beenrecently developed as a novel candidate for photovoltaic application with high stability and a maximumpower conversion efficiency of 12.5%. This article summarized these newly emerging 2D PVK materialsand their uses in solar cells. The structural, physical, and chemical properties as well as the classificationof 2D PVK materials are discussed. The photovoltaic performance parameters of various 2D perovsldtesolar cells （2D PSCs） are summarized and their device stability is compared with conventional 3Dperovskite solar cells （3D PSCs）. It has been concluded that 2D PVKs show greater stability upon humidity,heat stress, and light intensity as compared to 3D analogues and act as a class of promising materials forapplication in solar cells.

Enhancing the long-term Na-storage cyclability of conversion-type iron selenide composite by construction of 3D inherited hyperbranched polymer buffering matrix

Electrochemical conversion reactions provide more selections for Na-storage materials, but the reaction suffers from low reversibility and poor cyclability. Introducing an electrochemically inactive component is a common strategy, but the effect is quite limited since it could not stabilize the structure during long-term cycling. In this study, a new approach is developed using an amino group-functioned hyperbranched polymer (AHP) as a template and electrode additive for the design of high-performance FeSe2-AHP composite with chemical interaction. The assembled FeSe2-AHP composite nanoneedles were prepared by the selenylation of FeS-AHP composite microflowers and entirely inherit the polymer network from the precursor. The amino groups of AHP in composite coordinate with iron cations to achieve uniform polymer dispersion in the composite, and maintain the molecular level mixed state during the long-term cycling. Moreover, the in-situ constructed uniform 3D elastic polymer network effectively accommodates volume expansion and alleviates nanoparticle aggregation during sodiation/de-sodiation. FeSe2-AHP composite provides a superior rate capability (584.8 mAh·g−1 at 20 A·g−1) and a remarkable cyclability with a capacity retention rate of 93.3% after 2,000 cycles. FeSe2-AHP composite shows a high pseudocapacitive behavior for the abundant nanometer interface established by AHP, enhancing the solid-state Na+ diffusion. The FeSe2-AHP anode is also compatible with Na3V2(PO4)3/C cathode in a full Na-ion battery, which provides a high-power performance (powering 51 LEDs). The work herein highlights an innovative and efficient strategy for conversion-type material design and demonstrates the function of chemical interaction of polymer additive in the enhancement of long-term cyclability for conversion electrode.

D-A structural protean small molecule donor materials for solution-processed organic solar cells

Under the synergistic effect of molecular design and devices engineering, small molecular organic solar cells have presented an unstoppable tendency for rapid development with putting forward donor- acceptor （D-A） structures. Up to now, the highest power conversion efficiency of small molecules has exceeded 11%, comparable to that of polymers. In this review, we summarize the high performance small molecule donors in various classes of typical donor-acceptor （D-A） structures and discuss their relationships briefly.

Organic functional materials based buffer layers for efficient perovskite solar cells

In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC development, device architecture and material design features, we exemplified the exciting progresses made in field by exploiting organic π-functional materials based hole and electron transport layers（HTLs and ETLs） to enable high-performance PVSCs.

Recent advances of metal fluoride compounds cathode materials for lithium ion batteries:a review

As the most successful new energy storage device developed in recent decades,lithium-ion batteries(LIBs)are ubiquitous in the modern society.However,current commercial LIBs comprising mainly intercalated cathode materials are limited by the theoretical energy density which cannot meet the high storing energy demanded by renewable applications.Compared to intercalation-type cathode materials,low-cost conversion-type cathode materials with a high theoretical specific capacity are expected to boost the overall energy of LIBs.Among the different conversion cathode materials,metal fluorides have become a popular research subject for their environmental friendliness,low toxicity,wide voltage range,and high theoretical specific capacity.In this review,we compare the energy storage performance of intercalation and conversion cathode materials based on thermodynamic calculation and summarize the main challenges.The common conversion-type cathode materials are described and their respective reaction mechanisms are discussed.In particular,the structural flaws and corresponding solutions and strategies are described.Finally,we discussed the prospective of metal fluorides and other conversion cathode materials to guide further research in this important field.