Research Highlights

Yolk-shell-structured (CrMnFeCoNi)3O4 high-entropy oxide anode for high-performance lithium-ion batteries

HEO-YS is synthesized via a rapid microwave-assisted solvothermal method. HEO-NP and HEO-YS show reversible capacities of 830 and 954 mAh g–1, respectively. HEO-YS exhibits superior rate capability and cycling stability. Yolk-shell structure accommodates volume change and enhances Li+ transport. Cycled HEO-YS shows a nanocrystalline structure with minimal long-range ordering.

Electrochimica Acta, 2025 [Link]

Modified multi-metal Prussian blue analogues toward high-performance cathode for sodium-ion battery

Prussian blue analogue (PBA) demonstrates great advantages as the cathodes for SIB owing to its simple synthesis method, inexpensive raw materials, and high theoretical specific capacity. Single phase multi-metal based PBA of Na1.92(Mn0.3Fe0.23Co0.3Ni0.17)[Fe(CN)6]0.88⋅2.16H2O with low contents of crystal water and [Fe(CN)6]4–defects was obtained by controlling the nucleation reaction rate via using sodium citrate as a chelating agent, and the assistance of N2 as an antioxidant and a protective gas. The obtained PBA with high purity and high crystallinity delivers a specific capacity of 120 mAh g−1, excellent rate capability, and impressive cycling performance with 82 % capacity retention after 1000 cycles.

Journal of Power Sources, 2024 [Link]

Fluoroethylene carbonate electrolyte additive for improved charge-discharge performance of Co-free high entropy spinel oxide anodes for lithium-ion batteries

Performance of (MnFeNiCrCu)3O4 HESO is heavily influenced by the nature of SEI.FEC-free electrolyte leads to inferior passivation and poor electrode performance.Optimal 10 wt% FEC enables excellent high-rate and long-term cycling performance. 10 wt% FEC enables a balanced amount of organic and inorganic species in SEI. 15 wt% FEC results in excessive formation of LiF, making SEI brittle and resistive.

Ceramic International Acta, 2024 [Link]

Binder-dependent electrochemical properties of high entropy oxide anodes for lithium-ion batteries

Binder effects on high-entropy (CrMnFeNiCu)3O4 anode performance are examined. PVDF, PNVF, NaCMC, Na alginate, and NaPAA binders are systematically compared. NaPAA increases electrode coulombic efficiency, rate capability, and cyclability. A capacity of 800 mAh g–1 and a 99 % capacity retention after 300 cycles are found. NaPAA reduces heat generation during thermal runaway and increases safety.

Electrochimica Acta, 2024 [Link]

High-Entropy Non-Flammable Ionic Liquid/Dimethoxymethane Composite Electrolyte for High-Performance Lithium-Ion Batteries

An ionic liquid/ether composite high-entropy electrolyte with a unique Li+ coordination structure that leads to an upgraded solid-electrolyte interphase and improved Li+ desolvation kinetics is developed. It exhibits high thermal stability, negligible corrosivity, and a large potential window, and is highly compatible with graphite, SiOx, and high-nickel LiNi0.8Co0.1Mn0.1O2 electrodes, showing great potential for battery applications.  

Advanced Science, 2024 [Link]

Engineering of Aromatic Naphthalene and Solvent Molecules to Optimize Chemical Prelithiation for Lithium-Ion Batteries

This study optimizes polyaromatic hydrocarbons and solvents to develop cost-effective and scalable chemical prelithiation recipes. The effects of the interaction time between Li metal, polyaromatic hydrocarbons, and solvent on prelithiation power are systematically investigated. An optimal recipe leads to a solid-electrolyte interphase with a balanced organic and inorganic composition, resulting in enhanced initial Coulombic efficiency, rate capability, and cycling stability of the prelithiated electrode. 

Advanced Science, 2024 [Link]

Core-Shell Si@SiOC Particles Synthesized Using Supercritical Carbon Dioxide Fluid for Superior Li-Ion Storage Performance

A unique supercritical carbon dioxide method to create core-shell Si@SiOC composite particles is developed. The conducting SiOC layer brings the particles closer together, benefiting electron and Li+ transport. In addition, the buffering SiOC layer can accommodate the Si volume change during lithiation/delithiation. The obtained Si@SiOC anode material has great potential for high-energy-density and high-reliability battery applications. 

Advanced Science, 2024 [Link]

Double Nitrogenation Layer Formed Using Nitric Oxide for Enhancing Li+ Storage Performance, Cycling Stability, and Safety of Si Electrodes

A unique double nitrogenation layer on Si cores is developed. The electrode with a double nitrogenation layer shows significantly suppressed exothermic reactions during thermal runaway. The Si/NO/C-N||LiNi0.8Co0.1Mn0.1O2 full cell demonstrates a high energy density of 585 Wh kg−1 and retains >90% of its initial capacity after 300 cycles. The proposed double nitrogenation method is facile, cost-effective, and scalable for practical application.

Advanced Science, 2024 [Link]

Enhanced Electrochemical Performance of Ca-Doped Na3V2(PO4)2F3/C Cathode Materials for Sodium-Ion Batteries

ACS Appl. Mater. Interfaces 2024, 16, 1, 496–506  [Link]

Self-Discharge Behavior of Graphitic Cathodes for Rechargeable Aluminum Batteries

Self-discharge properties of natural graphite and expanded graphite are studied. A wide d spacing and large surface area of graphite lead to fast self-discharge. Self-discharge loss is related to spontaneous deintercalation of AlCl4− anions. Increasing the charging rate or depth of charge increases the self-discharge rate. Electrolyte composition also alters the self-discharge properties of the graphite electrode. 

Advanced Functional Material, 2023 [Link]

Investigations on the lithium-ion and sodium-ion insertion behavior of amorphous sodium iron carbonophosphate using N-propyl-N-methylpyrrolidium bis-(fluorosulfonyl) imide based ionic liquid electrolyte

Journal of Power Sources, 2023 [Link]

N-containing carbon-coated β-Si3N4 enhances Sianodes for high-performance Li-ion batteries

The superior charge/discharge properties of β-Si3N4 over α-Si3N4 are confirmed. β-Si3N4 is partially consumed during lithiation to form a protective Li3N layer. With incorporated β-Si3N4 in a Si-based anode, Li15Si4 formation/dissolution upon charge/discharge is highly reversible. The crystallinity of β-Si3N4 is preserved after cycling, suppressing electrode deterioration. Combining β-Si3N4 and Si phases results in a clear synergy in specific capacities.

Advanced Science, 2023 [Link]

Secondary-phase-induced charge-discharge performance enhancement of Co-free high entropy spinel oxide electrodes for Li-ion batteries

Co-free cubic high entropy spinel oxide (HESO (C)) and cubic+tetragonal high entropy spinel oxide (HESO (C+T)) have been prepared using a solvothermal and hydrothermal methods, respectively. The secondary tetragonal spinel phase in HESO (C+T) introduces phase boundaries and extra defects/oxygen vacancies, that enhance the redox kinetics and electroactivity during the lithiation/delithiation reactions. A HESO (C+T)||LiNi0.8Co0.1Mn0.1O2 cell shows an attractive gravimetric energy density of ~610 Wh kg−1.

Advanced Functional Materials, 2023 [Link]

Binder-Controlled Pore Size Distribution of Carbon Electrodes to Mitigate Self-Discharge of Supercapacitors 

·     
Self-discharge has long been an issue that restricts application of supercapacitors.  Electrode self-discharge involves charge redistribution and Faradaic side reactions. A proper pore size distribution control of carbon electrodes mitigates self-discharge. A cost-effective strategy related to binder selection suppresses self-discharge. Charging rate, temperature, and voltage all affect self-discharge rate.

Carbon 204 (2023) 555-565 . [LINK]

Tape-cast Ce-substituted Li7La3Zr2O12 electrolyte for improving electrochemical performance of solid-state lithium batteries

Li7La3Zr2−xCexO12 (x = 0–0.15) garnet and a tape casting process are developed to increase electrolyte Li+ conductivity and reduce the interface resistance, which significantly improve the performance of solid-state lithium-metal batteries. 

Journal of Material Chemistry  A, 2022,10, 22512-22522 [Link]

Dual interface design of Ga-doped Li7La3Zr2O12/polymer composite electrolyte for solid-state lithium batteries

A spin-coating method was used to deposit an LGLZO CSE layer on top of an LFP cathode to improve the cathode/CSE interfacial contact. The Ga concentration in LGLZO was optimized. An IL interlayer was applied between the Li electrode and CSE to facilitate the Li+ transport. With these approaches, excellent SSLMB performance is demonstrated.

International Journal of Energy Research, 2022, 46, 17693. [Link]

Nitrogen-Doped Holey Graphene Additive for High-Performance Electric Double-Layer Supercapacitor 

Single-step, scalable, and residual-free method is developed to produce NHGNSs. GNS, HGNS, and NHGNS additives in AC electrodes are systematically compared. GNSs shield the AC surface from ion accessibility, decreasing electrode performance. NHGNSs improve electrode wettability, ion diffusion, interfacial conductivity. Effects of electrode additives on reliability of AC cells are first investigated.

Electrochimica Acta, 2022.

More detail: https://doi.org/10.1016/j.electacta.2022.140713

Charge-Discharge Mechanism of High-Entropy Co-Free Spinel Oxide Toward Li+ Storage Examined Using Operando Quick-Scanning X-ray Absorption Spectroscopy 

The charge storage mechanism of Co-Free HEO is studied using a novel and unique operando quick-scanning XAS technique. High-photon-flux synchrotron radiation is employed to increase XAS sensitivity. The XAS data are acquired in on-the-fly mode using a monochromator oscillation frequency of 2 Hz. Valence/coordination state variations and multiple transition steps of the constituent species upon charging/discharging are investigated in detail.

Advanced Science, 2022.

More detail: https://doi.org/10.1002/advs.202201219

Hierarchical Carbon Composites for High-Energy/Power-Density and High-Reliability Supercapacitors with Low Aging Rate 

AC/CNS/CNT was developed for electric double-layer capacitors (EDLCs). The facile fabrication method could be easily scaled up with high cost-effectiveness. The electrode conductivity was boosted with the optimal CNS/CNT ratio. A hierarchical carbon architecture could significantly improve charge-discharge capacitances, increase cell reliability, and decrease the aging-related degradation rate. 

ChemSusChem, 2022.

More detail: https://doi.org/10.1002/cssc.202200345

Effects of Elemental Modulation on Phase Purity and Electrochemical Properties of Co-free High-Entropy Spinel Oxide Anodes for Lithium-Ion Batteries

A series of Co-free spinel-type HEO anodes is fabricated via a facile hydrothermal method. Chemical composition of HEOs is critical to phase purity and oxygen vacancies. Entropy stabilization effects sustain the crystalline framework and electrode reversibility. An inactive spectator element is not needed for high cyclability of HEO electrodes. A (CrNiMnFeCu)3O4||LiNi0.8Co0.1Mn0.1O2 cell shows an energy density of 590 Wh kg−1.

Advanced Functional Material, 2022.

More detail: https://doi.org/10.1002/adfm.202110992

Improving high-temperature performance of lithium-rich cathode by roll-to-roll atomic layer deposition of titania nanocoating for lithium-ion batteries

Spatial atomic layer deposition was used to coat TiO2 layers on Li-rich cathode. TiO2-coated Li-rich cathodes are cycled within 2.0–4.8 V at 60 °C for 200 cycles. High-temperature rate capability and cyclic stability are strongly improved. TiO2 layer is capable of effectively alleviating metal migration and cation mixing. The technique provides a continuous coating on Li-rich cathodes with > 1.2 m min−1.

Journal of Energy storage, 2021.

More detail: https://doi.org/10.1016/j.est.2021.103348

High-Li+-fraction ether-side-chain pyrrolidinium–asymmetric imide ionic liquid electrolyte for high-energy-density Si//Ni-rich layered oxide Li-ion batteries

With Ether-chain pyrrolidinium and asymmetric imide enables a high Li+ fraction in IL electrolyte. Robust LiF- and Li3N-rich SEI has balanced organic/inorganic components is crucial. The long-existing rate capability problem of IL electrolyte has been overcome. The electrolyte suppresses the interfacial exothermic reactions of delithiated NCM-811. High energy density Si/CNT/G||NCM-811 full cell is demonstrated.

Chemical Engineering Journal, 2021.

More detail: https://doi.org/10.1016/j.cej.2021.132693

Co-free high entropy spinel oxide anode with controlled morphology and crystallinity for outstanding charge/discharge performance in Lithium-ion batteries

Hydrothermally synthesized Co-free high entropy spinel oxides with all metals being active. Crystallinity and particles size of the resulting (CrMnFeNiCu)3O4 controlled by post-annealing. Optimized anode exhibiting a high reversible capacity of 755 mAh g−1 at 50 mA g−1. An excellent 250-cycle stability of 99% capacity retention also demonstrated. Structure evolution investigated using in operando XRD and postmortem TEM.

Chemical Engineering Journal, 2021.

More detail: https://doi.org/10.1016/j.cej.2021.132658

High-Voltage Lithium-Metal Battery with Three-Dimensional Mesoporous Carbon Anode Host and Ether/Carbonate Binary Electrolyte 

Electrolyte and anode host materials are developed for lithium-metal batteries. The proposed electrolyte induces a robust SEI and withstands high potential. 1-D CNT, 2-D graphene, and 3-D CMK-8 carbon host materials are examined. CMK-8 structure can minimize the dead Li amount and suppress Li dendrite formation. Superior CE of 99.2% and great stability of up to 550 cycles are found for CMK-8.

Carbon, 2021

More detail: https://doi.org/10.1016/j.carbon.2021.08.087

Supercritical CO2-assisted SiOx/carbon multi-layer coating on Si anode for lithium-ion batteries

An eco-friendly, cost-effective, and scalable supercritical CO2 (SCCO2) process is developed for single-step production of a unique Si@SiOx@C anode for Li-ion batteries. Owing to gas-like diffusivity, low surface tension, and excellent permeability of SCCO2, a continuous SiOx layer that can buffer Si volume change is fabricated. The produced carbon film has low oxygen content and thus shows high electronic conductivity.

Advance Functional Materials

More detail: https://doi.org/10.1002/adfm.202104135

Hydrogenated Anatase and Rutile TiO2 for Sodium-Ion Battery Anodes

A low-cost, facile, and chemical-free hydrogenation process can can boost Na+ storage performance of TiO2 electrodes.

ACS Applied Energy Materials

More details: https://doi.org/10.1021/acsaem.1c00571

Ordered Nano-structured Mesoporous CMK-8 and Other Carbonaceous Cathodes for Rechargeable Aluminum Batteries

The unique bicontinuous electronic and ionic conduction pathways and meso-size 3-D open channels make CMK-8 a promising cathode material for rechargeable aluminum battery applications 

Chemical Engineering Journal

More details: https://doi.org/10.1016/j.cej.2021.129131

Optimizing the Mg Doping Concentration of Na3V2–xMgx(PO4)2F3

/C for Enhanced Sodiation/Desodiation Properties

Mg-doped Na3V2(PO4)2F3/C exhibits better performance, faster Na+ transport, and fewer structural changes on cycling as compared to undoped materials. 

ACS Sustainable Chemistry & Engineering 

More details: https://doi.org/10.1021/acssuschemeng.1c00418

Composition manipulation of bis(fluorosulfonyl)imide-based ionic liquid electrolyte for high-voltage graphite//LiNi0.5Mn1.5O4 lithium-ion batteries

The proposed high-safety bis(fluorosulfonyl)imide-based ionic liquid electrolyte allows a 5-V graphite//LNMO full cell to exhibit a high reversible capacity and long cycle life.

Chemical Engineering Journal

More details: https://doi.org/10.1016/j.cej.2021.128904

Creating electronic and ionic conductivity gradients for improving energy storage performance of ruthenium oxide electrodes

Robust Ru-based thin films are successfully fabricated by single- and multiple-annealing thermal decomposition methods and are utilized as high-performance electrodes for the supercapacitors. Two critical parameters, the annealing temperature and treatment duration, are engineered for synthesizing stable thin-film electrodes. The enhanced performance is attributed to the multistep thermal stages along with the layer-by-layer deposition, enabling enhanced heat transfer to individual thin layers. An optimal thermal treatment procedure is assessed empowering enhanced capacitive performance due to high hydrous RuO2·xH2O ratio, reduced crystalline structure, facile electrolyte wetting, and stable adhesion between the deposits and the Ti substrate.

Journal of Alloys and Compounds

More details: https://doi.org/10.1016/j.jallcom.2020.158013

Manipulation of Nitrogen-Heteroatom Configuration for Enhanced Charge-Storage Performance and Reliability of Nanoporous Carbon Electrodes

Nitrogen-containing functional groups are manipulated on carbon surface via melamine, ammonia, and nitric oxide doping methods. N-5 and N-6 groups markedly alter the specific surface area and pore size of activated carbon. N-O affects electrolyte wettability, whereas N- Q content is closely associated with carbon electronic conductivity. The N-Q-enriched and N-5/N-6-depleted sample most effectively suppresses leakage current and gas evolution of supercapacitors. With an appropriate carbon surface functionality, high performance and high reliability of supercapacitors can be achieved.

ACS Applied Material and Interfaces

More details: https://doi.org/10.1021/acsami.0c08440

Manipulation of Nitrogen-Heteroatom Configuration for Enhanced Charge-Storage Performance and Reliability of Nanoporous Carbon Electrodes

A nonflammable moderate-concentration LiFSI/FEC electrolyte creates robust SEI on a Si anode and enables a high cycling stability of Si//LiNi0.8Co0.1Mn0.1O2 cells. 

ACS Sustainable Chemistry & Engineering 

More details: https://doi.org/10.1021/acsami.0c08440

Ga-doped lithium lanthanum zirconium oxide electrolyte for solid-state Li batteries

Various dopants such as Al and Ga are doped into the LLZO samples, which are synthesized using a solid-state reaction method. The Al- and Ga-doped LLZO can transform to a cubic-phase garnet at 900 °C. After 1200 °C sintering, a Li2ZrO3 impurity phase is found for the Al-doped LLZO pellet, which still shows many voids and inhomogeneous particles on the surface. The Ga doping seems to be attractive since it can effectively stabilize the cubic phase and desired microstructure within 900–1200 °C. Based on the optimized Ga-doped LLZO (LGLZO), various electrolyte architecture designs are developed that include LGLZO pellet electrolytes with and without poly(ethylene oxide) (PEO)-lithium bis(trifluoromethylsulfonyl)imide (LiTFSI)-LGLZO coating, and hybrid electrolyte layers of PEO-LiTFSI, PEO-LGLZO, and PEO-LiTFSI-LGLZO composites. Li//LiFePO4 (LFP) cells with various types of electrolytes are assembled, and their charge-discharge properties are investigated. 

Electrochimica Acta 

More details: https://doi.org/10.1016/j.electacta.2020.136536

High entropy spinel oxide nanoparticles for superior lithiation–delithiation performance

High entropy spinel oxide (HESO) nanoparticles were first synthesized via a surfactant assisted hydrothermal method and used as a novel anode material in lithium-ion battery. The HESO consists of non-equimolar cations of Cr, Mn, Fe, Co, and Ni dispersed in two Wyckoff sites with various valence states. Due to a strong entropy-induced phase stabilization effect of the HESO, no inactive MgO structural pillars, which exclusively present in the reported rock salt type of high entropy oxides, is required to achieve high electrode cycling stability. Superior charge-discharge capacity of 1235 mAh g-1, the highest among all known HEOs, is obtained with 90% capacity retention after 200 cycles. The unique HESO is also characterized by plenty of oxygen vacancies and threedimensional Li+ transport pathways. Also, great high-rate performance, i.e.,500 mAh g-1@2000 mA g-1, of the HESO electrode is demonstrated

Journal of Material Chemistry A

More details: https://doi.org/10.1039/D0TA04844E

A holey graphene additive for boosting performance of electric double-layer supercapacitors

Holey graphene nanosheets (HGNSs) are prepared by an ultra-rapid heating process. Heating temperature of 900 °C is optimal for HGNSs as an EDLC active material. However, HGNS-900 shows a low volumetric capacitance and is not practical useful. In contrast, HGNS-900 is an effective performance promoter for activated carbon (AC) electrodes. AC/HGNS-900 composite is a promising electrode material for non-aqueous EDLC applications.

Polymers

More details: https://doi.org/10.3390/polym12040765

Hydrous ruthenium oxide-tantalum pentoxide thin film electrodes prepared by thermal decomposition for electrochemical capacitors

In this work, we have fabricated high-performance thin-film electrodes for electrochemical capacitors (ECs) via thermal decomposition syntheses of RuO2–Ta2O5 coating layers on Ti substrates. The influences of decomposition temperature as well as the Ru/Ta molar ratio on material and electrochemical properties of the EC electrodes are systematically investigated. The thermal decomposition of 300 °C preserves a large fraction of hydrous RuO2·xH2O within the hybrid oxide and consequently improves the electrode capacitance. The amorphous Ta2O5 incorporation can manipulate the RuO2 crystallinity and thus its specific capacitance. An optimal Ru/Ta molar ratio of 7:3 is determined for the RuO2–Ta2O5 electrode, which can deliver an energy density of 4.8 Wh kg−1 at a power density of 8720 W kg−1. In addition, an excellent durability of 97.6% capacitance retention after 3000 cycles is found for this electrode. 

Ceramic International 

More details: https://doi.org/10.1016/j.ceramint.2020.03.236

A Novel Moisture-Insensitive and Low-Corrosivity Ionic Liquid Electrolyte for Rechargeable Aluminum Batteries

A new moisture-insensitive and low-corrosivity Al2Cl7−-free 4-ethylpyridine/AlCl3 ionic liquid electrolyte is proposed. In situ synchrotron X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy mapping confirm that a stage-3 graphite intercalation compound forms at the end of charging and that the deintercalation of AlCl4− occurs upon discharging, allowing a reversible capacity of 95 mAh g−1 and great cycleability. 

Advance Functional Materials

More details: https://doi.org/10.1002/adfm.201909565

Composition Modulation of Ionic Liquid Hybrid Electrolyte for 5 V Lithium-Ion Batteries

By modulating ionic liquid/carbonate ratio and LiPF6 concentration in the hybrid electrolyte, Al corrosion and electrolyte decomposition side reactions at 5 V (vs. Li+/Li) can be suppressed. The proposed electrolyte shows great compatibility with LiNi0.5Mn1.5O4 and Si electrodes, high thermal stability, low flammability, and good wettability toward a polyethylene separator.

ACS Applied Material and Interfaces

More details: https://doi.org/10.1021/acsami.9b12915

Hybrid electrolyte enables safe and practical 5-V LiNi0.5Mn1.5O4 batteries 

By modulating LiTFSI concentration and ionic liquid ratio in the hybrid electrolyte, Al corrosion and electrolyte decomposition side reactions at 5 V (vs. Li + /Li) can be suppressed.The proposed electrolyte shows great compatibility with both LiNi0.5Mn1.5O4 cathode and graphite anode, high thermal stability, low flammability, and good wettability toward a polyethylene separator.

Journal of Materials Chemistry A 

More details: https://doi.org/10.1039/C9TA04147H

Moderately concentrated electrolyte improves solid–electrolyte interphase and sodium storage performance of hard carbon

Moderately concentrated electrolyte with satisfactory conductivity and viscosity can create a robust organic–inorganic balanced solid–electrolyte interphase. The crucial roles of ethylene carbonate are explored. With this electolyte, the first-cycle and steady-state coulombic efficiency of the hard carbon electrode is increased to 85% and >99.9%, respectively, and the reversible sodiation/desodiation capacities at high rates are markedly improved. In addition, 95% of the initial capacity can be retained after 500 charge−discharge cycles.

Energy Storage Materials

More details: https://doi.org/10.1016/j.ensm.2018.04.022

Three-dimensional carbon framework anode improves sodiation–desodiation properties in ionic liquid electrolyte

Ionic liquid (IL), characterized by wide potential window, high thermal stability, negligible volatility, and low flammability, is a promising electrolyte for sodium-ion batteries (NIBs). However, the typical NIB anodes, such as hard carbon, show unsatisfactory capacities and poor charge–discharge rate capability in IL electrolyte at room temperature. A three-dimensional carbon framework (3-D CF) constructed with graphene nanosheets and carbon nanospheres is developed to address this issue. With this unique nano-architecture, the interfacial charge transfer, IL electrolyte infiltration, and Na+ transport can be improved at room temperature. As a consequence, this electrode shows superior sodiation–desodiation properties, with a charge–discharge efficiency being stable over 250 cycles in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide IL electrolyte. We also confirm that the 3-D CF electrode exhibits higher Coulombic efficiency and better cycling stability in the IL electrolyte than those found in conventional organic carbonate electrolyte, especially at an elevated temperature, due to the different chemistry of the solid–electrolyte interphase. The total heat releases of the sodiated 3-D CF samples contacted with IL and carbonate electrolytes, measured with differential scanning calorimetry up to 300 °C, are 250 and 805 J g–1, respectively. The combination of the 3-D CF electrode and IL electrolyte shows great potential for NIB applications. 

Nano Energy 

More details: https://doi.org/10.1016/j.nanoen.2018.04.043

Electrochemical Na+ storage properties of SnO2/graphene anodes in carbonate-based and ionic liquid electrolytes

Electrolyte formulations are vital for the proper functioning of Na-ion batteries. A systematic study is conducted to optimize the electrolyte for a SnO2/graphene anode, which is prepared via a supercritical-CO2-assisted synthesis method. The effects of a propylene carbonate (PC) and ethylene carbonate (EC) solvent combination and a fluoroethylene carbonate (FEC) additive on the electrode charge–discharge properties are examined. Incorporations of EC and FEC promote the formation of a more robust solid electrolyte interphase layer, improving the cyclic stability of the electrode compared to that found for an electrode in a PC-only electrolyte containing 1 M NaClO4 salt. Nevertheless, at 60 °C, an N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ionic liquid electrolyte clearly outperforms the PC/EC/FEC carbonate-based electrolyte in terms of electrode capacity, rate capability, and cyclic stability. This work indicates that the electrode sodiation/desodiation performance remarkably depends on the electrolyte composition, which should be optimized for various application demands and operation temperatures of batteries. 

Journal of Materials Chemistry A 

More details: https://doi.org/10.1039/C7TA03226A

High dispersion of 1-nm SnO2 particles between graphene nanosheets constructed using supercritical CO2 fluid for sodium-ion battery anodes

Supercritical CO2 (SCCO2) fluid, which has gas-like diffusivity, extremely low viscosity, and near-zero surface tension, is used to synthesize SnO2 nanoparticles (a 1-nm diameter is achievable), which are uniformly dispersed and tightly anchored on graphene nanosheets (GNSs) and carbon nanotubes (CNTs). This study tunes the SCCO2 temperature (and thus its fluid density) and finds that this factor crucially affects the SnO2 size and distribution, determining the resulting electrochemical properties. The sodiation/desodiation mechanism of the SnO2/GNS electrode is examined using synchrotron ex situ X-ray absorption and X-ray diffraction techniques, together with transmission electron microscopy. We confirm that while the oxide conversion reaction is reversible, the sluggish Sn–Na alloying/dealloying reaction is responsible for the lower measured capacity as compared to the theoretical value. The first-cycle efficiency loss is mainly attributed to the trapping of Na in the electrode surface solid electrolyte interphase layer. 

Nano Energy 

More details: https://doi.org/10.1016/j.nanoen.2016.08.044

Highly enhanced electrochemical performance of ultrafine CuO nanoparticles confined in ordered mesoporous carbons as anode materials for sodium-ion batteries

Ultrafine CuO nanoparticles are successfully encapsulated into two ordered mesoporous carbons (OMCs) with different pore architectures, namely CMK-8 with a 3D cubic mesostructure and CMK-3 with a 2D hexagonal mesostructure, and used as anodes in sodium-ion batteries. The electrochemical test results demonstrate that the CuO@CMK-8 nanocomposite exhibits superior electrochemical performance. The remarkable enhancement of the performance of the CuO@CMK-8 nanocomposite can be attributed to the electrically conductive network of CMK-8 in the CuO@CMK-8 nanocomposite wherein the ultra-small CuO nanoparticles supported on CMK-8 act as a synergistic elastic buffer. Furthermore, ex situ XRD, SEM and TEM measurements provide deeper insights to the reversible conversion reaction in the CuO@CMK-8 nanocomposite system during the sodiation/desodiation process. 

Journal of Materials Chemistry A 

More details: https://doi.org/10.1039/C6TA05238J

Microplasma-assisted bottom-up synthesis of graphene nanosheets with superior sodium-ion storage performance

A microplasma-assisted chemical vapor deposition technique is used to produce graphene nanosheets (denoted as MPGNSs). This bottom-up synthesis is a one-step, facile, green, and continuous process. The obtained MPGNSs have higher crystallinity, less defects, and higher tap density compared to those of conventional reduced graphene oxides (RGOs). Galvanostatic intermittent titration and cyclic voltammetry techniques are used to explore the effects of the aforementioned material properties on the electrochemical Na+ storage behavior. MPGNSs are able to deliver a high capacity of 250 mA h g−1 (@0.03 A g−1) and show excellent rate capability (110 mA h g−1@5 A g−1), with both values being clearly superior to those of the RGOs synthesized via a top-down graphite exfoliation method. 

Journal of Materials Chemistry A 

More details: https://doi.org/10.1039/C6TA00743K