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A new concept is developed using locally an enriched PAA binder to enhance the structural stability of the electrode.

This work proposes to directly use transition metal (cobalt) powder as the precursor for the synthesis of LiCoO2, solving the problem of structural instability and rapid capacity decay caused by order–disorder phase transitions without any modification.

Funding Information: This work has been funded by the Academy of Finland Project (Grant No. 348403), the Start-up Funding offered by Ningbo University of Technology to J.Y., and the Start-up Package of T10108 Professorship offered by Aalto University to Y.L. Q.Q. and P.Y. acknowledge financial support from the China Scholarship Council (Grant Nos. 201906150134 and 202006120046). Publisher Copyright: © 2022 The Authors. Published by American Chemical Society. Nonaqueous redox flow batteries (NARFBs) hold potential application as an electricity energy storage for intermittent renewable energy and can operate with high voltage and energy density. However, their further development is impeded by lack of a proper membrane. Herein, a flexible freestanding anionic metal-organic framework (MOF)-based membrane is prepared through a solution casting method, with an anionic MOF (UiO-66-SO3Li) and polyvinylidene fluoride. The prepared membrane shows an impressive ionic selectivity (37.6) of Li+ to N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium (Fc1N112+) ions and high ionic conductivity. Benefiting from the unique micropore structure of MOF and the anionic transport channels of Li+ across the membrane, the resultant Li-based hybrid NARFB delivers a high-capacity retention (99.95% per cycle) over 500 cycles with a well-assembled stable interphase after long time lithium plating/stripping, which decreases the voltage efficiency during the cycling. Calculations reveal that the membrane easily desolvates Li+ in the unique micropore structure of MOF before Li deposition occurs, which suppresses parasitic reaction and accelerates Li uniform deposition. This work provides a viable method to design bifunctional NARFB membranes which achieve ion sieving and ion exchange functions.

The Ni-rich cathode holds great promise for high energy density lithium-ion batteries because of its high capacity and operating voltage. However, crucial problems such as cation disorder, structural degradation, side reactions, and microcracks become serious with increasing nickel content. Herein, a novel and facile sol/antisolvent coating modification of Ni-rich layered oxide LiNi

Increasing working voltage is a promising way to increase the energy density of lithium-ion batteries. Cycling and rate performance deteriorated due to excessive electrolyte decomposition and uncontrolled formation of a cathode-electrolyte interface (CEI) layer at a high voltage. A new concept is proposed to construct a high-voltage-stable electrode-electrolyte interface. An elastomeric poly(dimethyl siloxane) (PDMS) binder is incorporated into the electrode to modify the LiNi

Anatase titanium dioxide (TiO2) has attracted considerable attention as a promising alternative rechargeable ion battery electrode due to excellent operation safety, good reversible capacity, huge natural abundance, and good environmental friendliness. However, several intrinsic critical drawbacks including relatively low capacity and poor electric conductivity significantly limit its practical application. Large amount of research has been performed to solve these issues, resulting in three well-developed optimization strategies including decreasing the material size to nanoscale, compositing anatase TiO2 with electron conductive components, and constructing hierarchical structures. In this review, considerable studies about anatase TiO2 electrode materials are summarized in a chronological perspective. Unique insights into the general and detailed evolution trends of the research on applications of anatase TiO2 electrode materials in energy storage devices are provided. In addition, a spotlight on the future trends to advance both the fundamental understanding and practical applications of the anatase TiO2 electrode materials is provided.

A new concept of electrode processing with tiny amounts of multi-functional microporous PIM additives was established as an alternative to binder-containing and binder-free electrodes, leading to enhanced electrochemical performance.

The conventional lithium-ion battery technology relies on the liquid carbonate-based electrolyte solution, which causes excessive side reactions, serious risk of electrolyte leakage, high flammability, and significant safety hazards. In this work, phosphonate-functionalized imidazolium ionic liquid (PFIL) is synthesized and used as a gel polymer electrolyte (GPE) to replace the organic carbonate-based electrolyte solution. The as-prepared ionic liquid-based gel polymer electrolyte (IL-GPE) shows low crystallinity, flame retardance, and excellent electrochemical performance. Thanks to the fast double channel transport of lithium ions in the IL-GPE electrolyte, a high ionic conductivity of 0.48 mS cm

Funding Information: This work was supported by the National Natural Science Foundation of China (Grant no. 21636007 ), the Start-up Foundation offered by Ningbo University of Technology to J.S. Yuan, and the Start-up Package of T10108 Professorship offered by Aalto University to Y.D. Li. Publisher Copyright: © 2022 Elsevier Ltd Redox flow battery (RFB) has been widely considered to be one of the most promising grid-scale energy-storage technology. The membrane, namely separator, serves as preventing the crossover of the positive and negative active species, while facilitating the transport of the supporting electrolyte ions, is crucial to achieve a high performance and a long-term stability for an RFB. Advances in RFBs require high-performance and low-cost membranes with high ion-selective transport for the application of large-scale energy storage. Two-dimensional (2D) materials have emerged as promising functional materials owing to their atomic-scale thickness and unique physical/chemical properties, which have great potential in the application of RFB membrane. Focusing on the recent state-of-the-art of 2D materials, in this mini review, various 2D materials applied in the membrane for RFB are briefly introduced. A perspective on the near-future developments of 2D materials in RFB membranes is presented.

Lithium metal battery has attracted tremendous attention because of its superior energy density. However, it suffers poor cyclic stability and serious safety risk due to severe side reactions between lithium and electrolyte solution, and excessive growth of lithium dendrite, which can be even worse at high temperatures and high voltage. To tackle this issue, solvation structure manipulation is carried out in the ADFN electrolyte solution, containing co-solvents of dimethoxy ethane (DME), Fluoroethylene carbonate (FEC), adiponitrile (ADN), and Lithium bis(fluorosulfonyl)imide (LiFSI, 1.0 M), and lithium nitrate (LiNO3, 0.1 M). A large-sized solvation sheath with a more inorganic component is constructed as indicated by both the molecular dynamic simulation and Raman characterization. The unique solvation structure generates a stable SEI layer rich in inorganic species, which suppresses continuous consumption of electrolyte solvent and inhibits lithium dendrite growth as confirmed by both SEM and XPS analysis. The electrochemical performance is boosted with respect to the Li||Cu, Li||Li, Li||LFP and Li||NCM523 cells via the solvation structure tuning in the ADFN electrolyte solution. Improved cyclic stability, reversible capacities, and rate performance are demonstrated by both the Li||LFP and Li||NCM523 cells, where the Li||LFP cells exhibit outstanding performance at both room temperature and high temperatures of 80 °C and 90 °C. This work provides fundamental insights about the ADN solvation and innovative strategy to manipulate the solvation of lithium ions, which delivers a simple way to further optimize Li-ion electrolyte for wide-temperature and high voltage applications.

Increasing working voltage of cathode has been identified as one of the most promising strategies to increase energy density of the lithium-ion batteries. It is of crucial importance to suppress side reactions and control the formation of a cathode electrolyte interface (CEI) on the cathode surface in a high voltage range. In this work, sulfur is utilized to increase the working voltage of LiNi0.5Co0.2Mn0.3O2(NCM 523) to 4.5 V as demonstrated by both the NCM523/Li half-cell and NCM 523/graphite full cell. When a tiny amount of sulfur (0.1 mg mL-1) is added to the blank electrolyte of ethylene carbonate (EC) and dimethyl carbonate (DMC) (3:7 by volume), the cycling stability and rate performance are greatly improved in the NCM523/Li half-cell. The capacity retention over 200 cycles at 170 mA g-1 (1.0 C) is increased from 61.2 to 82.0%. The capacity at a high current density of 850 mA g-1 (5.0 C) is increased from 92 mAh g-1 to 120 mAh g-1. Because the addition of sulfur also enhances the performance of the Li/graphite half-cell, improved performance is demonstrated by the NCM 523/graphite full cell as well. The mechanism is interpreted based on various characterizations. It is revealed that the preferential oxidation of sulfur at the cathode surface suppress decomposition of electrolyte solvent. Because only a tiny amount of sulfur is added into the electrolyte solution, excessive decomposition of sulfur is avoided, leading to improved electrochemical performance.

Silicon anode has a huge potential to replace graphite anode. Nevertheless, it shows poor long-term cyclic stability and rate capability due to a huge volume change upon lithiation and intrinsic se...

Continuous fast pyrolysis is developed for in situ synthesis of ultra‐small metal oxide nanoparticles embedded into three‐dimensional macroporous carbon matrix as demonstrated by the TiO2/carbon nanohybrid. The TiO2 nanoparticles with the average size of 4.6 nm ± 0.6 nm are uniformly distributed in the in situ generated macroporous carbon matrix. When evaluated as an anode in a lithium‐ion battery, the macroporous TiO2/C nanohybrid exhibits a reversible capacity of 483 mAh g–1 after 500 cycles at a current density of 67 mA g–1, which is 3.6 times higher than that of the TiO2/C calcined in a conventional batchwise way. Besides, the capacity retains 93 mAh g–1 at a high current density of 670 mA g–1. It reveals that the continuous fast pyrolysis is an efficient method to fabricate carbon composition based metal oxides as lithium‐ion battery anode materials.

Micro‐sized porous silicon‐based anode materials gain much interest due to good cycling stability, high rate performance, reasonable tap density and low processing cost. Self‐templating process is developed to construct micro‐sized macro‐/mesoporous silicon through magnesiothermic reduction of Stöber silica. The size of the silica particles plays a vital role in the structure control of the porous silicon. In this work, silica particles with a diameter of 130 nm are used as templates to guide the synthesis of micro‐sized macro‐/mesoporous silicon. The magnesiothermic reduction temperature is varied in a systematic way to reveal the self‐templating mechanism comprehensively. It is found that the silica particles with small diameter of 130 nm still exercise the self‐templating effect during the magnesiothermic reduction process in the temperature range of 700 to 900°C. Based on the experimental results, the structure‐property correlation of the porous silicon anode is unveiled. Improved electrochemical performance is demonstrated by the porous silicon compared to the commercial nano‐sized silicon.

Ultrafine SnO2/Sn nanoparticles encapsulated into the adjustable mesoporous carbon matrix has been successfully fabricated by a facile route. The mesoporous carbon effectively improve the conductivity of the SnO2/Sn, prevent the aggregation, accommodate the strain of volume change and provide high interface area with the electrolyte, thus resulting in excellent cycling performance. A reversible capacity of 1105 mAh g–1 still retained after 290 cycles at 200 mA g–1, and the capacity still can keep at 107 mAh g–1 at high current density of 10 A g–1. The porous structures by the in situ SiOx template provide an appropriate specific surface area, which contributes to a relatively high capacitive contribution.

Lithium secondary batteries (LSBs) have witnessed explosive growth in the last decade. A wide operating temperature window is crucial for practical applications. A new concept is developed to expand the temperature window between −20 °C and 150 °C, where a competitive decomposition process between the electrolyte and solvent is manipulated with adiponitrile (ADN) over a wide temperature range. The decomposition of ethylene carbonate (EC) solvent and anions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium oxalyldifluoroborate (LiODFB) is regulated with ADN via a temperature-dependent lithium solvation mechanism. As a result, a SEI layer with a rich inorganic component is formed at elevated temperatures, leading to improved performance in lithium titanate (LTO)/Li, lithium iron phosphate (LFP)/Li, and LiNi0.5Co0.2Mn0.3O2 (NCM523)/Li batteries over a wide temperature range. It enables a coulombic efficiency (CE) of 97.39% at 100 °C and more than 100 hours of cycling of Li/Li batteries at 150 °C, as well as stable cycling of LFP/Li batteries in the temperature range between 120 °C and −20 °C. Stable cycling performance is demonstrated with the LTO/Li batteries over a wider temperature range from −40 °C to 150 °C. High-temperature electrochemical stability is exhibited at 5C, with a capacity retention ratio of 87.94% at 120 °C and 99.93% at 100 °C after 1000 cycles.

Highlights The PEDOT:PSS flexible electrodes with a unique CF3SO3H treatment exhibited high electrical characteristics and stability.An energy level tuning effect was induced to create a suitable work function.Flexible organic solar cells yielded a record-high efficiency of 16.61%, a high flexibility, and a good thermal stability. Electronic supplementary material The online version of this article (10.1007/s40820-020-00566-3) contains supplementary material, which is available to authorized users., Nonfullerene organic solar cells (OSCs) have achieved breakthrough with pushing the efficiency exceeding 17%. While this shed light on OSC commercialization, high-performance flexible OSCs should be pursued through solution manufacturing. Herein, we report a solution-processed flexible OSC based on a transparent conducting PEDOT:PSS anode doped with trifluoromethanesulfonic acid (CF3SO3H). Through a low-concentration and low-temperature CF3SO3H doping, the conducting polymer anodes exhibited a main sheet resistance of 35 Ω sq−1 (minimum value: 32 Ω sq−1), a raised work function (≈ 5.0 eV), a superior wettability, and a high electrical stability. The high work function minimized the energy level mismatch among the anodes, hole-transporting layers and electron-donors of the active layers, thereby leading to an enhanced carrier extraction. The solution-processed flexible OSCs yielded a record-high efficiency of 16.41% (maximum value: 16.61%). Besides, the flexible OSCs afforded the 1000 cyclic bending tests at the radius of 1.5 mm and the long-time thermal treatments at 85 °C, demonstrating a high flexibility and a good thermal stability. Electronic supplementary material The online version of this article (10.1007/s40820-020-00566-3) contains supplementary material, which is available to authorized users.

Binders play a crucial role in maintaining mechanical integrity of electrodes in lithium-ion batteries. However, the conventional binders lack proper elasticity, and they are not suitable for high-performance silicon anodes featuring huge volume change during cycling. Herein, a poly(siloxane imide) copolymer (PSI) has been designed, synthesized, and utilized as a binder for silicon-based anodes. A rigidness/softness coupling mechanism is demonstrated by the PSI binder, which can accommodate volume expansion of the silicon anode upon lithiation. The electrochemical performance in terms of cyclic stability and rate capability can be effectively improved with the PSI binder as demonstrated by a silicon nanoparticle anode.

Silicon anodes have attracted much attention owing to their high theoretical capacity. Nonetheless, an inevitable and enormous volumetric expansion of silicon in the lithiated state restrained the development of the silicon anode for lithium-ion batteries. Fortunately, the utilization of the high-performance binder is a promising and effective way to overcome such obstacles. Herein, a polymer of intrinsic microporosity (PIM) is applied as the binder for the silicon anode, which is composed of a rigid polymer backbone, an intrinsic porous structure, and active carboxyl groups (PIM-COOH). Compared to the traditional binder, both the long-term stability and rate performance of the electrode using PIM-COOH as the binder are significantly improved. The mechanism responsible for the enhanced performance is investigated. The PIM-COOH binder provides stronger adhesion toward the current collector than the conventional binders. The unique rigid polymer backbone and porous structure of the PIM-COOH binder enable a good capability to withstand the volume change and external stress generated by the Si anode. The porous structure of the PIM-COOH binder enhances lithium-ion transportation compared to the SA binder, which improves rate performance of the silicon anode. This work provides a unique insight into design, synthesis, and utilization of the binders for lithium-ion batteries.