Search

Formic acid is an efficient processing additive for Li4Ti5O12 anodes, but the amount has to be carefully optimized. Fluoroethylene carbonate as electrolyte additive can further enhance the performance by facilitating the interfacial charge transfer.

Lithium batteries occupy the large-scale electric mobility market raising concerns about the environmental impact of cell production, especially regarding the use of poly(vinylidene difluoride) (teratogenic) and N-methyl-2-pyrrolidone (NMP, harmful). To avoid their use, an aqueous electrode processing route is utilized in which a water-soluble hybrid acrylic-fluoropolymer together with sodium carboxymethyl cellulose is used as binder, and a thin phosphate coating layer is in situ formed on the surface of the nickel-rich cathode during electrode processing. The resulting electrodes achieve a comparable performance to that of NMP-based electrodes in conventional organic carbonate-based electrolyte (LP30). Subsequently, an ionic liquid electrolyte (ILE) is employed to replace the organic electrolyte, building stable electrode/electrolyte interphases on the surface of the nickel-rich positive electrode (cathode) and metallic lithium negative electrode (anode). In such ILE, the aqueously processed electrodes achieve high cycling stability with a capacity retention of 91% after 1000 cycles (20 °C). In addition, a high capacity of more than 2.5 mAh cm-2 is achieved for high loading electrodes (≈15 mg cm-2 ) by using a modified ILE with 5% vinylene carbonate additive. A path to achieve environmentally friendly electrode manufacturing while maintaining their outstanding performance and structural integrity is demonstrated. ispartof: SMALL vol:18 issue:42 ispartof: location:Germany status: published

The use of cobalt-free LiNi0.5Mn1.5O4 (LNMO) would provide a great leap forward towards the realization of sustainable lithium-ion batteries. However, the high operating voltage remains to be a great challenge for the cathode/electrolyte stability. Herein, we report a rational material design to address these challenges by carefully tuning the synthesis parameters in order to engineer LNMO crystals with tailored surface facets, providing an exceptional rate capability and improved interfacial stability. The additional introduction of protective TMPOx coatings further enhances the long-term cycling stability, in particular, at elevated cut-off potentials up to 4.95 V, increased temperature of 40 °C, and high dis-/charge rates. As a result of the careful design of the LNMO active material particles, lithium-ion cells employing this material together with Li4Ti5O12 anodes provide an excellent rate capability with 80% of the low-rate capacity at fast dis-/charge rates of 10C combined with highly stable cycling at such high rate, as highlighted by a capacity fading of less than 5% after 1000 cycles.

To tackle the poor chemical/electrochemical stability of Li

Seawater batteries (SWBs) have been mostly researched for large scale energy storage and (sub-)marine applications. In a SWB, the aqueous catholyte (seawater) and a non-aqueous anolyte (aprotic solvent solution) are physically separated by a NASICON solid electrolyte membrane. Given the practically unlimited Na+ ion supply from seawater, the energy storage is only limited by the amount of Na stored in the negative electrode. Therefore, the highest volumetric and gravimetric energy densities can be achieved by storing Na metal without the need for a host material. To achieve safe realization of such a cell, a compact, metal-less anode design is herein demonstrated for the first time. The anode compartment integrates the NASICON solid electrolyte, a Na-ion conductive solid-state polymer electrolyte (Na-SPE), having a high ionic conductivity (over 1 mS cm−1 at moderate room temperature), and a negative electrode current collector. The reactive Na metal is not employed in the cell construction, but it is harvested from seawater upon charge (power to metal) and reconverted into energy upon the discharge process (metal to power). The overall round-trip energy efficiency (RTE) of the devices is over 85% at room temperature.

NASICON-type Li

High-voltage cathode materials, granting high-energy density lithium batteries, face the challenge of developing functional electrolytes enabling their stable operation at voltages higher than 4 V (vs. Li+/Li). Non-volatile and poorly flammable ionic liquid electrolytes (ILEs) are successfully applied to overcome this challenge, even with low-Co or Co-free positive electrode materials. With the ionic liquid-based electrolytes, the cathodes exhibit remarkable electrochemical performance, achieving initial specific capacity above 200 mAh g-1 and outstanding capacity retention (up to 88% over 1000 cycles). More importantly, these electrolytes enable average Coulombic efficiency as high as 99.94%. The excellent compatibility of the ILEs with the high-voltage positive electrode materials enables the realization of cells achieving rather high specific energies.

Solid-state electrolytes (SSEs) are expected to play a decisive role for the realization of safer rechargeable batteries and may, additionally, allow for the employment of lithium-metal anodes, thus, paving the way for significantly higher energy densities. 1, 2 There are essentially two main groups of SSEs: (i) polymer and (ii) inorganic solids. The latter can be divided, e.g., into sulfide and oxide based electrolytes. 3 Among the oxides, the so-called NASICON-type electrolytes such as LAGP (lithium aluminum germanium phosphate) are considered as attractive low-cost alternative compared to sulfides. 4 Nonetheless, the incompatibility of LAGP with lithium metal accompanied by the formation of highly resistive interfacial reaction products, detrimentally affecting cycle life and rate capability, remain a great challenge. 5 To overcome this issue, the introduction of polyether (e.g., polyethylene oxide, PEO) as protective interlayer between the lithium-metal anode and the LAGP SSE was proposed. 6, 7, 8 The successful use of such interlayers, however, requires a fast and efficient charge transfer across this interlayer. Herein, we present a comprehensive investigation of PEO-based interlayers comprising varying amounts of ionic liquid-based electrolytes, which consist ofN-butyl-N-methyl pyrrolidinium-based and lithium cations as well as bis(fluorosulfonyl)imide (FSI-) and bis(trifluoromethanesulfonyl)imide (TFSI-) anions. Optimized compositions and the incorporation of selected additives further enhances the charge transfer across this interlayer and the two interfaces with the LAGP electrolyte and lithium metal, enabling long-term stable cycle life and good rate capability of the resulting lithium-metal battery cells. References 1. Gao, Z. et al. Promises, Challenges, and Recent Progress of Inorganic Solid-State Electrolytes for All-Solid-State Lithium Batteries. Adv. Mater. 30, 1705702 (2018). 2. Famprikis, T., Canepa, P., Dawson, J. A., Islam, M. S. & Masquelier, C. Fundamentals of inorganic solid-state electrolytes for batteries. Nat. Mater. 18, 1278–1291 (2019). 3. Fan, L., Wei, S., Li, S., Li, Q. & Lu, Y. Recent Progress of the Solid-State Electrolytes for High-Energy Metal-Based Batteries. Adv. Energy Mater. 8, 1702657 (2018). 4. Bachman, J. C. et al. Inorganic Solid-State Electrolytes for Lithium Batteries: Mechanisms and Properties Governing Ion Conduction. Chem. Rev. 116, 140–62 (2016). 5. Hartmann, P. et al. Degradation of NASICON-Type Materials in Contact with Lithium Metal: Formation of Mixed Conducting Interphases (MCI) on Solid Electrolytes. J. Phys. Chem. C 117, 21064–21074 (2013). 6. Wang, C. et al. Suppression of Lithium Dendrite Formation by Using LAGP-PEO (LiTFSI) Composite Solid Electrolyte and Lithium Metal Anode Modified by PEO (LiTFSI) in All-Solid-State Lithium Batteries. ACS Appl. Mater. Interfaces 9, 13694–13702 (2017). 7. Bosubabu, D., Sivaraj, J., Sampathkumar, R. & Ramesha, K. LAGP|Li Interface Modification through a Wetted Polypropylene Interlayer for Solid State Li-Ion and Li–S batteries. ACS Appl. Energy Mater. 2, 4118–4125 (2019). 8. Wang, L., Liu, D., Huang, T., Geng, Z. & Yu, A. Reducing interfacial resistance of a Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte/electrode interface by polymer interlayer protection. RSC Adv. 10, 10038–10045 (2020).

Implementing aqueous electrode processing for lithium-ion cathodes is one of the key steps toward the achievement of environmentally benign battery production and of utmost importance in light of t...

A new electrolyte (anolyte) for the negative electrode of seawater batteries, based on the combination of two ionic liquids (ILs), a sodium salt, and a SEI-forming additive, is herein reported. The quaternary anolyte is composed of N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (0.6 mol fraction), N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl) imide) (0.3 mol fraction), and sodium bis(fluorosulfonyl)imide (0.1 mol fraction). Ethylene carbonate (5 wt% with respect to the ILs and salt mixture) is added to promote SEI formation. The thermal, physicochemical, and electrochemical characterization of the quaternary electrolyte indicate its suitability as an anolyte, as well as the formation of a highly stable interface with the negative (hard carbon) electrode. Lab-scale seawater full cells employing a hard carbon anode and the ionic liquid-based quaternary anolyte show remarkable results in terms of capacity, cyclability, and rate capability at room temperature. Additionally, these cells showed better energy efficiency (voltage efficiency) and cyclability than those based on a conventional organic carbonate-based anolyte.

Lithium metal is considered as one of the most promising anode candidates for high-energy batteries [1-3]. However, safety concerns induced by the formation of Li dendrites largely hinder the practical application of lithium-metal batteries [4]. It is anticipated that the use of non-flammable inorganic solid-state electrolytes can resolve these safety issues [5], but solid ceramic electrolytes generally suffer from poor physical contact with the electrode and poor electro-/chemical stability at the electrolyte|electrode interface [6]. Herein, we report on a thin and flexible hybrid electrolyte composed of NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP), a polymer binder, and a small amount of an ionic liquid-based electrolyte. To reinforce the interfacial stability between LATP and Li, we coat an ultrathin polysiloxane-based single-ion conducting polymer (PSiO) on the Li metal surface via a simple dip-coating method. The implementation of PSiO-coated Li (PSiO@Li) in symmetric PSiO@Li||PSiO@Li cells enables a substantial extension of the cycle life, yielding >2,000 h of stable lithium stripping-plating. The full-cells comprising PSiO@Li as the negative electrode, LiNi0.88Co0.09Mn0.03O2 (NCM88) as the positive electrode active material, and the aforementioned hybrid electrolyte exhibit substantially enhanced rate capability at high dis-/charge rates above 0.5C and greatly prolonged cycle life at 1C. The superior performance achieved herein is mainly attributed to: (1) the prevented direct contact between LATP and Li, thus avoiding the reduction of LATP and the formation of mixed ion-electron conducting interphases; (2) the regulated Li+ flux at the electrode|electrolyte interface, ensuring homogeneous Li+ stripping-plating; and (3) the promoted intimate contact between PSiO and Li via the formation of Si−O−Li bonds. References [1] T. Li, X.-Q. Zhang, P. Shi, Q. Zhang, Joule, 3 (2019) 2647-2661. [2] B. Horstmann, J. Shi, R. Amine, M. Werres, X. He, H. Jia, F. Hausen, I. Cekic-Laskovic, S. Wiemers-Meyer, J. Lopez, D. Galvez-Aranda, F. Baakes, D. Bresser, C.-C. Su, Y. Xu, W. Xu, P. Jakes, R.-A. Eichel, E. Figgemeier, U. Krewer, J.M. Seminario, P.B. Balbuena, C. Wang, S. Passerini, Y. Shao-Horn, M. Winter, K. Amine, R. Kostecki, A. Latz, Energy Environ. Sci., 14 (2021) 5289-5314. [3] S. Wang, P. Xiong, J. Zhang, G. Wang, Energy Storage Materials, 29 (2020) 310-331. [4] Z. Yu, Y. Cui, Z. Bao, Cell Rep. Phy. Sci., 1 (2020) 100119. [5] S. Xin, Y. You, S. Wang, H.-C. Gao, Y.-X. Yin, Y.-G. Guo, ACS Energy Lett., 2 (2017) 1385-1394. [6] A. Banerjee, X. Wang, C. Fang, E.A. Wu, Y.S. Meng, Chem. Rev., 120 (2020) 6878-6933.

The lithium metal anode is regarded as ideal for high-energy rechargeable batteries. Unfortunately, the uncontrolled lithium dendritic growth and the infinite volume expansion upon cycling result in low Coulombic efficiency, fast capacity decay and safety issues. Herein, a mismatch electrical-conductivity framework has been designed as a stable host to regulate lithium deposition behaviour. Due to the ionic conductivity of the lithiophilic layer and the electron conductivity of hollow carbon nanofibres (HCF), lithium metal is preferentially deposited into and encapsulated by the HCF, resulting in greatly improved electrochemical performance. The heat generation upon lithium storage and release in the Al2O3 coated HCF (A–HCF) during cycling is lower compared to the plating/stripping on copper foil. The A-HCF electrodes show high Coulombic efficiency (97%) upon 500 cycles employing a conventional, alkyl carbonate-based electrolyte, demonstrating improved reversibility of Li plating/stripping. Complete cells assembled employing LiNi0.8Co0.1Mn0.1O2 (NMC811)-based positive electrodes exhibit high capacity retention (94%) after 120 cycles at 1 C, delivering a high energy density (363 Wh per kg of NMC811). Even upon cycling at 5 C rate, the cells, employing less than three times excess lithium, deliver a very high capacity (133 mAh per g of NMC811) for 50 cycles.

The synthesis of a new ionic liquid (IL), consisting of the symmetric tetra-butyl-phosphonium (P4444+) cation and the (nonafluorobutanesulfonyl)(trifluoromethanesulfonyl)imide (IM14–) anion, via a facile and environmentally-friendly aqueous route is reported. The novel P4444IM14 IL demonstrates excellent thermal and electrochemical stability (beyond 6 V vs. Li+/Li0 (against Ni-foil)) in combination with good near-room temperature conductivity and ionic liquid characteristics, such as non-measurable volatility and exceptional flame-retardant properties. Employed as electrolyte component in Li-metal cells together with the high-voltage, Li1.2Ni0.2Mn0.6O2 positive electrode material, enables an initial discharge capacity of 264 mA h g-1 at 12.5 mA g−1 and improved initial Coulombic efficiency. Additionally, the discharge capacity retention is promising (92.3% after 50 cycles and 84.4% after 100 cycles) when compared with using a conventional organic carbonate-based electrolyte (55.5% after 50 cycles). Further development of this ionic liquid electrolyte may facilitate the practical application of Li-metal anodes in high-voltage/high-energy lithium batteries.

Summary High-energy-density lithium-metal batteries face the challenge of developing functional electrolytes enabling both the stabilization of the lithium-metal negative electrode and high-voltage positive electrodes (> 4 V versus Li+/Li). Herein, a low-volatility and non-flammable ionic liquid electrolyte (ILE) incorporating two anions, bis(fluorosulfonyl) imide (FSI) and bis(trifluoromethanesulfonyl)imide (TFSI), is successfully applied to overcome this challenge, employing the high-energy, low-Co, and Ni-rich positive-electrode material, LiNi0.88Co0.09Mn0.03O2 (NCM88), in Li-metal batteries. With this specific electrolyte, the cathode exhibits remarkable electrochemical performance, achieving an initial specific capacity of 214 mAh g−1 and outstanding capacity retention of 88% over 1,000 cycles. More importantly, this electrolyte enables an average Coulombic efficiency of 99.94%. The excellent compatibility of the dual-anion ILE with both the lithium metal (50 μm) and the high-voltage positive-electrode material enables the realization of Li-metal cells achieving specific energies of more than 560 Wh kg−1 based on their combined active material masses.

Red‐phosphorus semi‐liquid electrodes are investigated as anodes for metal‐free rechargeable Na‐seawater batteries with high energy density. The red‐phosphors semi‐liquid electrode, made by mixing P/C composite powder with a redox‐mediators‐based electrolyte solution (P/C @ Na‐BP‐PYRs), enables a high areal capacity of 26 mAh using a small coin cell. The two redox mediators act as reducing and oxidizing species for the red‐phosphorus. Sodium‐seawater batteries (Na‐SWB) are considered among the most promising electrochemical devices for large‐scale energy storage and the marine sector. In fact, by employing an open‐structured cathode, they benefit from the unlimited supply of sodium from seawater. This means, that the energy of such systems is intrinsically limited by the capacity of the anode. In order to increase the energy of Na‐SWB, it is therefore necessary to introduce a high‐capacity anode such as, e.g., red phosphorus. However, due to its large volume changes upon charge/discharge processes, obtaining thick electrodes and large areal capacity is extremely challenging. Herein, the areal/absolute capacity of the red phosphorus anode is increased by employing a semi‐liquid electrode, which includes two redox mediators, i.e., sodium‐biphenyl and sodium‐pyrene, as reducing and oxidizing species for the exploitation of the full red phosphorus capacity. As a result, the red phosphorus semi‐liquid anode in Na‐SWB provides a high‐capacity of 15 mAh cm–2 in a static anode, showing great energy storage potential for operation in flow‐mode when storing the semi‐liquid negative electrode in a storage tank., publishedVersion

NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) is a promising solid electrolyte (SE) candidate for next-generation solid-state batteries. However, its use in solid-state composite electrodes is inhibited by its stiffness, which results in poor interparticle contact unless high-temperature treatments are applied. The poor LATP-LATP and LATP-active material in the positive electrode (cathode) composite produced at ambient temperature yield poor ionic conductivity, impeding the electrode's performance. Herein, we focus on the optimization of the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 (NCM811)-LATP composite electrodes made by tape casting, taking advantage of a small fraction of an ionic liquid electrolyte (ILE) filling the composite cathode porosity. The incorporated LATP particles are found to closely surround the large NCM811 secondary particles, partially filling the composite electrode pores and resulting in a porosity reduction from 37 vol % (NCM811 only) to 32 vol % (NCM811-LATP). After filling up the majority of the electrode porosity with ILE, the NCM811-LATP composite electrodes offer improved capacity retention upon both long-term cycling tests (>99.3% after 200 cycles) and high-rate tests (>70% at 2 C-rate), due to the more stable LATP|NCM811 interface, and facilitated Li+ diffusion in the composite electrode bulk. Results obtained from proof-of-concepts monopolar (3.0-4.3 V) and bipolar-stacked (6.0-8.6 V) cells are reported.

International audience; The development of new materials for tomorrow's electrochemical energy storage technologies, based on thoroughly designed molecular architectures is at the forefront of materials research. In this line, we report herein the development of a new class of organic lithium-ion battery electrolytes, thermotropic liquid crystalline single-ion conductors, for which the single-ion charge transport is decoupled from the molecular dynamics (i. e., obeys Arrhenius-type conductivity) just like in inorganic (single-)ion conductors. Focusing on an in-depth understanding of the structure-to-transport interplay and the demonstration of the proof-of-concept, we provide also strategies for their further development, as illustrated by the introduction of additional ionic groups to increase the charge carrier density, which results in a substantially enhanced ionic conductivity especially at lower temperatures.

The development of new materials for tomorrow's electrochemical energy storage technologies, based on thoroughly designed molecular architectures is at the forefront of materials research. In this line, we report herein the development of a new class of organic lithium-ion battery electrolytes, thermotropic liquid crystalline single-ion conductors, for which the single-ion charge transport is decoupled from the molecular dynamics (i. e., obeys Arrhenius-type conductivity) just like in inorganic (single-)ion conductors. Focusing on an in-depth understanding of the structure-to-transport interplay and the demonstration of the proof-of-concept, we provide also strategies for their further development, as illustrated by the introduction of additional ionic groups to increase the charge carrier density, which results in a substantially enhanced ionic conductivity especially at lower temperatures.

peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 10/07/2021 Addition of electrolyte additives (ethylene or vinylene carbonate) is shown to dramatically improve the cycling stability and capacity retention (1600 mAhg-1) of Si nanowires (NWs) in a safe ionic liquid (IL) electrolyte (0.1LiTFSI-0.6PYR13FSI-0.3PYR13TFSI) . We show using post-mortem SEM and TEM, a distinct difference in morphologies of the active material after cycling in the presence or absence of the additives. The difference in performance is shown by post-mortem XPS analysis to arise from a notable increase in irreversible silicate formation in the absence of the carbonate additives. The composition of the solid electrolyte interphase (SEI) formed at the active material surface was further analysed using XPS as a function of the IL components revealing that the SEI was primarily made up of N, F and S containing compounds from the degradation of the TFSI and FSI anions.

Li-garnets are promising inorganic ceramic solid electrolytes for lithium metal batteries, showing good electrochemical stability with Li anode. However, their brittle and stiff nature restricts their intimate contact with both the electrodes, hence presenting high interfacial resistance to the ionic mobility. To address this issue, a strategy employing ionic liquid electrolyte (ILE) thin interlayers at the electrodes/electrolyte interfaces is adopted, which helps overcome the barrier for ion transport. The chemically stable ILE improves the electrodes-solid electrolyte contact, significantly reducing the interfacial resistance at both the positive and negative electrodes interfaces. This results in the more homogeneous deposition of metallic lithium at the negative electrode, suppressing the dendrite growth across the solid electrolyte even at high current densities of 0.3 mA cm−2. Further, the improved interface Li/electrolyte interface results in decreasing the overpotential of symmetric Li/Li cells from 1.35 to 0.35 V. The ILE modified Li/LLZO/LFP cells stacked either in monopolar or bipolar configurations show excellent electrochemical performance. In particular, the bipolar cell operates at a high voltage (≈8 V) and delivers specific capacity as high as 145 mAh g−1 with a coulombic efficiency greater than 99%., publishedVersion

Sodium biphenyl is investigated as an anolyte for sodium metal/seawater batteries. The sodium biphenyl anolyte enables an excellent capacity retention over 80 cycles in anode‐free seawater battery full‐cell configuration. This is because the sodium biphenyl behaves as a “mediator/ carrier” for sodium transport in the negative electrode compartment thanks to its simultaneous ionic and electronic conductivity. Sodium‐based battery systems have recently attracted increasing research interest due to the abundant resources employed. Among various material candidates for the negative electrode, sodium metal provides the highest capacity of theoretically 1165 mAh g−1 and a very low redox potential of −2.71 versus the standard hydrogen electrode. However, the high reactivity of sodium metal toward the commonly used electrolytes results in severe side reactions, including the evolution of gaseous decomposition products, and, in addition, the risk of dendritic sodium growth, potentially causing a disastrous short circuit of the cell. Herein, the use of sodium biphenyl (Na‐BP) as anolyte for the Na–seawater batteries (Na–SWB) is investigated. The catholyte for the open‐structured positive electrode is natural seawater with sodium cations dissolved therein. Remarkably, the significant electronic and ionic conductivities of the Na‐BP anolyte enable a low overpotential for the sodium deposition upon charge, allowing for high capacity and excellent capacity retention for 80 cycles in full Na–SWB. Additionally, the Na‐BP anolyte suppresses gas evolution and dendrite growth by forming a homogeneous surface layer on the metallic negative electrode., publishedVersion

The recently introduced seawater battery concept is an eco-friendly energy storage system that offers appealing electrochemical performance. Its radically innovative design, compared to conventional lithium-ion batteries, makes use of seawater as an almost infinite sodium reservoir for the positive electrode and, thereby, avoids the use of expensive, scarce, and toxic elements like nickel and cobalt. So far, the problems identified mostly originate from the available negative electrode active materials. In this study, a starch-derived hard carbon was used to optimize the system. Due to its improved disordered structure compared with commercial hard carbon, the starch hard carbon exhibits an increased reversible capacity, current-rate capability, and cycling ability. The material, in fact, depicts a high maximum power density of 700 W kg−1 (based on hard carbon weight) upon discharge at 900 mA g−1, while still being active at 2700 mA g−1. These results represent an important step toward practical application of the sodium-based seawater battery technology.

In this work, a facile and potentially scalable self-template synthesis of bi-component ZnO/ZnFe2O4/N-doped C micro-polyhedrons with hierarchical hollow structure (ZZFO-C) is presented. These are obtained through calcination of a single bi-metallic metal-organic framework (MOF) precursor (ZIF-ZnFe, molar ratio of 3:1). The resulting material shows a high surface area and is constituted by the organized assembly of numerous nanoparticles sub-unit (with size in the range of 20 nm). By tuning the annealing conditions, porous ZnO/ZnFe2O4 (ZZFO) micro-polyhedrons are obtained. The ZZFO-C composite materials are studied as anodes for LIBs exhibiting remarkable energy storage performance, such as, large reversible capacity (ca. 1000 mA h g−1 after 100 cycles at 200 mA g−1), excellent rate capability and cycling stability. After high-rate capacity testing (1000 cycles at 2.0 A g−1), ZZFO-C shows an excellent reversible capacity of 620 mA h g−1. The excellent performance of ZZFO-C arises from its unique hierarchical hollow structure and the synergy between the two active components and the N-doped carbon matrix. The electrochemical reaction mechanism and structure phase changes upon the initial lithiation are identified via in situ X-ray diffraction studies.

This work reports the performance of LiNi0.4Co0.2Mn0.4O2 electrodes employing sodium carboxymethyl cellulose as the binder (CMC/NCM). Compared with conventional organic PVDF-based electrodes, the CMC/NCM electrodes display very uniform distribution of NCM and carbon particles together with strong adhesion among the particles and with the current collector, leading to significantly mitigated crack formation and delamination of the electrode upon repeated delithiation/lithiation processes. Additionally, these electrodes offer enhanced Li+ diffusion kinetics, reduced polarization, therefore, excellent high C-rate capability, and extremely stable cycling performance even at elevated temperature (60 °C). Benefiting from the features of low cost, environmentally friendliness, and easy disposability-recyclability, the water-soluble CMC is a promising binder for practical application in energy storage systems. Accepted version

The preparation of hybrid ceramic-polymer electrolytes, consisting of 70 wt% of Li+ cation conducting Li7La3Zr2O12 (LLZO) and 30 wt% of P(EO)15LiTFSI polymer electrolyte, through a solvent-free procedure is reported. The LLZO-P(EO)15LiTFSI hybrid electrolytes exhibit remarkable improvement in terms of flexibility and processability with respect to pure LLZO ceramic electrolytes. The physicochemical and electrochemical investigation shows the effect of LLZO annealing, resulting in ion conduction gain. However, slow charge transfer at the ceramic-polymer interface is also observed especially at higher temperatures. Nevertheless, improved compatibility with lithium metal anodes and good Li stripping/plating behavior are exhibited by the LLZO-P(EO)15LiTFSI hybrid electrolytes with respect to P(EO)15LiTFSI. © 2017 Elsevier B.V.

In this work is reported the successful synthesis of 1D nanobar-like LiNi0.4Co0.2Mn0.4O2 (N-NCM), preferentially exposing the {010} electrochemically active facets. The material is obtained via a precipitation process followed by a calcination step. Upon calcination at 800 °C, the material delivers a high initial reversible capacity of 177.1 mA h g−1 at 0.1C, while at higher current densities (1C, 2C, 5C and 10C), it still delivers 152.8, 141.7, 122.7 and 104.2 mA h g−1, respectively. After 100 cycles, the material exhibits high capacity retention values, ca. 91% (0.1C) and 94% (10C). The good electrochemical performance is attributed to the synthesis design strategy leading to 1D nanobars with exposed {010} electrochemically active facets, which provide a more open structure for unimpeded Li+ migration. In addition, the diffusion pathway of lithium ions is greatly reduced because of the nano-sized bar shape. All these factors play a decisive role in achieving significantly enhanced lithium ion diffusivity, and thus superior high C-rate capability and greatly improved long-term cycling stability.

Cheaper and greener ILs: A one-pot synthetic process using water as the only solvent is designed to obtain ionic liquids (ILs) in a yield of approximately 95 mol % and purity greater than 99.3 wt % in a processing time of only 1 h. Moreover, no heating is required to carry out the reaction. The one-pot ILs have similar properties to ILs prepared by conventional procedures and show high performance without any further purification through sorbents.An innovative one-pot synthetic process that uses water as the only processing solvent was used to obtain ionic liquids (ILs) in a yield of approximately 95 mol % and purity greater than 99.3 wt % (, publishedVersion

The current insertion anode chemistries are approaching their capacity limits; thus, alloying reaction anode materials with high theoretical specific capacity are investigated as potential alternatives for lithium-ion batteries. However, their performance is far from being satisfactory because of the large volume change and severe capacity decay that occurs upon lithium alloying and dealloying processes. To address these problems, we propose and demonstrate a versatile strategy that makes use of the electronic reaction confinement via the synthesis of ultrasmall Ge nanoparticles (10 nm) uniformly confined in a matrix of larger spherical carbon particles (Ge⊂C spheres). This architecture provides free pathways for electron transport and Li+ diffusion, allowing for the alloying reaction of the Ge nanoparticles. The thickness change of electrodes containing such a material, monitored byan in situ electrochemical dilatometer, is rather limited and reversible, confirming the excellent mechanical integrity of the confined electrode. As a result, these electrodes exhibit high reversible capacity (1310 mAh g-1, 0.1C) and very impressive cycling ability (92% after 1000 cycles at 2C). A prototype device employing such an alloying electrode material in combination with LiNi0.8Mn0.1Co0.1O2 offers a high energy density of 250 Wh kg-1.

Despite layered LiNi

Herein, a Mn-based metal–organic framework is used as a precursor to obtain well-defined α-MnS/S-doped C microrod composites. Ultrasmall α-MnS nanoparticles (3–5 nm) uniformly embedded in S-doped carbonaceous mesoporous frameworks (α-MnS/SCMFs) are obtained in a simple sulfidation reaction. As-obtained α-MnS/SCMFs shows outstanding lithium storage performance, with a specific capacity of 1383 mAh g−1 in the 300th cycle or 1500 mAh g−1 in the 120th cycle (at 200 mA g−1) using copper or nickel foil as the current collector, respectively. The significant (pseudo)capacitive contribution and the stable composite structure of the electrodes result in impressive rate capabilities and outstanding long-term cycling stability. Importantly, in situ X-ray diffraction measurements studies on electrodes employing various metal foils/disks as current collector reveal the occurrence of the conversion reaction of CuS at (de)lithiation process when using copper foil as the current collector. This constitutes the first report of the reaction mechanism for α-MnS, eventually forming metallic Mn and Li2S. In situ dilatometry measurements demonstrate that the peculiar structure of α-MnS/SCMFs effectively restrains the electrode volume variation upon repeated (dis)charge processes. Finally, α-MnS/SCMFs electrodes present an impressive performance when coupled in a full cell with commercial LiMn1/3Co1/3Ni1/3O2 cathodes., publishedVersion