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LiNi 0.5 Mn 1.5 O 4 (LNMO), with its spinel symmetry, emerges as a promising cathode material for high-voltage lithium-ion batteries (LIBs). Nonetheless, the vulnerability of LNMO to interfacial degradation, particularly electrolyte breakdown during high-voltage operation, compromises its long-term cycling performance. To overcome this longstanding challenge, a slurry additive-polyester-urethane-acrylate (PEUA)-to form a multi-functional ultra-thin electrode coating, enhancing the lifespan and energy density of LIBs is introduced. Comprehensive characterizations and theoretical analyses reveal that the PEUA slurry additive effectively maintains electrode integrity, facilitates electrons and lithium ions transport, and inhibits hazardous side reactions, thus preventing the by-products from triggering cathode-electrolyte-anode interface crosstalk. Consequently, the 5 V LNMO || Li cell with PEUA slurry additive maintains a high-capacity retention of 97.8%, with improved cycling stability at high-temperature and full-cell configurations. This crosstalk-mitigation strategy offers a promising avenue for extending the lifespan and electrochemical performance of high-voltage cobalt-free cathodes, advancing the practical use of high-energy density LIB technology., (© 2024 Wiley‐VCH GmbH.)

In this study, a novel concept of multipoint anionic bridge (MAB) is proposed and proved, which utilizes anions with different sites to connect with the asymmetric solvation structure (ASS). Compared to usual solvation structures, this study utilizes the multifunctional groups of difluoro(oxalate)borate anion (ODFB - ), which can connect with Li + . By tailoring the concentration, the anion serves as a bridge between different solvated structures. The electrolyte is investigated through in situ techniques and simulations to draw correlations between different solvation structures and reaction pathways. The proposed design demonstrates remarkable high-temperature performance on both the anode and cathode sides, enabling stable cycling of LCO||graphite (0.5 Ah, 1.0 C) pouch cell for over 200 cycles at 80 °C and facilitating Li||MCMB and Li||LFP cells to deliver stable performance for 200 cycles at 100 °C. This work paves the way for the development of high-performance electrolyte systems by designing and using new multipoint anions to construct ASSs., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

The stability of the commercial electrolyte is linked to the internal solvent molecule, particularly in enhancing the stability of these molecules. Hereby, we introduce a dual function strategy involving hydrogen bond induced solvent molecules and the in situ fabrication cathode-electrolyte interphase (CEI) to address this issue. The additive N -(4-(2,5-dioxo-4-oxazolidinyl)butyl)-2,2,2-trifluoroacetamide (DOTFA), with its oxazolidinyl and trifluoroacetamide functional units, establishes hydrogen bonds with the solvent, forming CEI films on the cathode surface that enhance the antioxidation ability of the electrolyte. These hydrogen bonds contribute to enhancing the high-pressure structural stability of the solvent molecule. Additionally, the uniform and robust in situ constructed CEI films act as a shield, protecting the cathode from various side reactions and enhancing interface compatibility. By incorporation of the DOTFA additive in the electrolyte, lithium-ion batteries with NCM811 cathodes exhibit excellent cycling performance. The work highlights the significance of dual function in solvent molecules and provides an effective method for enhancing the antioxidation ability of the electrolyte.

To mitigate the environmental impact of the improper disposal of spent LiFePO 4 batteries and reduce resource waste, the development of LiFePO 4 recycling technologies is of paramount importance. Meanwhile, olivine-structured NaFePO 4 in sodium-ion batteries has received great attention, due to its high theoretical specific capacity of 154 mAh g -1 and excellent stability. However, olivine NaFePO 4 only can be synthesized from olivine LiFePO 4 . Accordingly, in this proposal, developing the continuous flow electrochemical solid-liquid reactor-based metal ion insertion technology is to utilize the olivine FePO 4 , recycled from LiFePO 4 , and to synthesize NaFePO 4 . Additionally, by employing I - as the reducing agent, NaFePO 4 is successfully synthesized with a discharge-specific capacity of 134 mAh g -1 at 0.1C and a remarkable capacity retention rate of 86.5% after 100 cycles at 0.2C. And the reasons for sodium deficiency in the synthesized NFP are elucidated through first-principles calculations. Furthermore, the kinetics of the solid-solution reaction 2 (Na 2/3+β PO 4 → Na 1-α FePO 4 ) mechanism improve with cycling and are sensitive to temperature. Utilizing a minimal amount of reducing agent in the electrochemical reactor, NaFePO 4 synthesis is successfully achieved. This innovative approach offers a new, cost-effective, and environmentally friendly strategy for preparing NaFePO 4 from recycling LiFePO 4 ., (© 2024 Wiley‐VCH GmbH.)

The LiCoO 2 (LCO) cathode is foreseen for extensive commercial applications owing to its high specific capacity and stability. Therefore, there is considerable interest in further enhancing its specific capacity by increasing the charging voltage. However, single-crystal LCO suffers from a significant capacity degradation when charged to 4.5 V due to the irreversible phase transition and unstable structure. Herein, an ultra-small amount (0.5% wt. in the electrode) of multi-functional PIM-1 (a polymer with intrinsic microporosity) additive is utilized to prepare a kind of binder-free electrode. PIM-1 modulates the solvation structure of LiPF 6 due to its unique structure, which helps to form a stable, robust, and inorganic-rich cathod-eelectrolyte interphase (CEI) film on the surface of LCO at a high voltage of 4.5 V. This reduces the irreversible phase transition of LCO, thereby enhancing the cyclic stability and improving the rate performance, providing new perspectives for the electrodes fabrication and improving LCO-based high-energy-density cathodes., (© 2024 The Authors. Small published by Wiley‐VCH GmbH.)

Nickel-rich layered oxide cathodes, such as LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), are prevalent in high-power batteries owing to their high energy density. However, these cathodes suffer from undesirable side reactions occurring at the cathode/liquid electrolyte interface, leading to inferior interface stability and poor cycle life. To address these issues, herein, an amphiphilic diblock copolymer poly(dimethylsiloxane)- block -poly(acrylic acid) (PDMS- b -PAA) along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is utilized for modifying the electrode surface. This modification causes a thin and stable cathode-electrolyte interface (CEI) on the surface of NCM523 particles, as evidenced by XPS, TEM, and EIS analysis. The introduction of this modified interface successfully suppresses the capacity fading of NCM523. After 200 cycles at a rate of 1.0 C, the capacity of the modified NCM523 cathode is 108.7 mAh g -1 , with a capacity retention of 82.8%, while the control samples without the polymer modification display a capacity retention of 72.7%. These results outline the distinct advantage of electrode surface modification with diblock copolymers/LiTFSI for the stabilization of Ni-rich layered oxide cathodes.

Lithium-ion batteries (LIBs) are known for their high energy density but exhibit poor cyclic stability and safety risks due to side reactions between the electrode and electrolyte. To address these issues, a novel approach involving construction of a polymer coating layer (PCL) via in situ self-polymerization using 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFBM) as an electrolyte additive on the cathode is proposed. The PCL endows the electrolyte with a high onset oxidation potential (4.78 V) and lithium-ion transference number (0.52). The uniform and robust in situ constructed PCL can effectively inhibit the severe irreversible side reactions and suppress harmful reactions, thus providing a protective barrier against degradation. The resulting Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 batteries exhibit an improved discharge capacity retention of 80% at 1C over 100 cycles. These results demonstrate that the in situ self-polymerization strategy holds promising potential for enhancing LIB performance and long-term stability, especially when high-voltage cathode materials are used.

Niobium pentoxides (Nb 2 O 5 ) present great potential as next-generation anode candidates due to exceptional lithium-ion intercalation kinetics, considerably high capacity, and reasonable redox potential. Although four phases of Nb 2 O 5 including hexagonal, orthorhombic, tetragonal, and monoclinic polymorphs show diverse characteristics in electrochemical performance, stable lifetime, high specific capacity, and fast intercalation properties cannot be delivered simultaneously with a single phase. Herein, this issue is addressed by generating a homogeneous mixture of orthorhombic and monoclinic crystals at the nanoscale. Reversible lithium-ion intercalation/deintercalation of the monoclinic phase is achieved, and exceptional lithium storage sites are created at the interface of the two phases. As a result, electrochemical features of stable lifetime from the orthorhombic phase and high specific performance from the monoclinic phase are harmoniously combined. This dual-phase Nb 2 O 5 /C nanohybrids deliver as high as 380 mA h g -1 (0.01-3.0 V) and 184 mA h g -1 (1.0-3.0 V) after 200 cycles. The essential principle of property enhancement is further confirmed through in situ XRD measurements and DFT calculations. The dual-phase concept can be further applied on electrodes with multiphases to achieve high electrochemical performance.

Ni-rich cathode materials exhibit superior energy densities and have attracted interest among both research and industrial fields; whereas, their practical application is hindered by the intrinsic drawbacks brought by the high nickel content such as structural instability and rapid capacity fading. Herein, in situ formation of a LiBO 2 coating layer and spinel phase layer is achieved on the surface of a Ni-rich cathode material via a boric acid etching method at the precursor state. The spinel phase is considered to have a 3D lithium diffusion tunnel and hence faster diffusion kinetics. Moreover, the LiBO 2 layer possesses excellent (electro)chemical inertness and can suppress electrolyte decomposition, resulting in a more inorganic and stable cathode-electrolyte interface. The surface reconstructed sample exhibits better cyclic stability (93.3% capacity retention vs 85.3% for the pristine sample at 1 C for 100 cycles) and rate performance. The superiority of this surface reconstruction is demonstrated by a series of electrochemical techniques and characterization methods including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), post-mortem X-ray photoelectron spectroscopy (XPS) analysis, and density functional theory (DFT) calculations.

Na-based layered transition metal oxides with an O3-type structure are considered promising cathodes for sodium-ion batteries. However, rapid capacity fading, and poor rate performance caused by serious structural changes and interfacial degradation hamper their use. In this study, a NaPO 3 surface modified O3-type layered NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode is synthesized, with improved high-voltage stability through protecting layer against acid attack, which is achieved by a solid-gas reaction between the cathode particles and gaseous P 2 O 5 . The NaPO 3 nanolayer on the surface effectively stabilizes the crystal structure by inhibiting surface parasitic reactions and increasing the observed average voltage. Superior cyclic stability is exhibited by the surface-modified cathode (80.1% vs 63.6%) after 150 cycles at 1 C in the wide voltage range of 2.0 V-4.2 V (vs Na + /Na). Moreover, benefiting from the inherent ionic conduction of NaPO 3 , the surface-modified cathode presents excellent rate capability (103 mAh g -1  vs 60 mAh g -1 ) at 10 C. The outcome of this study demonstrates a practically relevant approach to develop high rate and durable sodium-ion battery technology., (© 2023 Wiley-VCH GmbH.)

The irreversible capacity loss of lithium-ion batteries during initial cycling directly leads to a decrease in energy density, and promising lithium cathode replenishment can significantly alleviate this problem. In response to the problems of complex preparation, instability in air, and unfavorable residue of the conventional cathode lithium replenishment materials, a Li 2 CO 3 /carbon nanocomposite is prepared and utilized as the lithium replenishment material. With high-speed ball-milling, a nanocomposite with a tight embedment structured Li 2 CO 3 /Ketjen Black (KB) composite composed of nanosized Li 2 CO 3 and KB is synthesized. The decomposition potential of Li 2 CO 3 is effectively decreased to 3.8 V, and the amount of the active lithium ion being released is significantly increased, corresponding to a specific capacity of 645.2 mAh·g -1 during the initial charging cycle. It has been introduced into the full-cells composed of the NCM523 cathode and graphite anode, resulting in a capacity increase of 44 mAh·g -1 in the initial cycle and a 26.4% improvement in capacity retention over 100 cycles. The working mechanism of the Li 2 CO 3 /KB nanocomposite as the lithium replenishment agent has been discussed. The outcome of the work provides a practically feasible route to realize lithium-ion battery technology with improved energy density and cycling life.

A layered Li[Ni x Co y Mn 1- x - y ]O 2 (NCM)-based cathode is preferred for its high theoretical specific capacity. However, the two main issues that limit its practical application are severe safety issues and excessive capacity decay. A new electrode processing approach is proposed to synergistically enhance the electrochemical and safety performance. The polyimide's (PI) precursor is spin-coated on the LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) electrode sheet, and the homogeneous sulfonated PI layer is in situ produced by thermal imidization reaction. The PI-spin coated (PSC) layer provides improvements in capacity retention (86.47% vs 53.77% after 150 cycles at 1 C) and rate performance (99.21% enhancement at 5 C) as demonstrated by the NCM523-PSC||Li half-cell. The NCM523-PSC||graphite pouch full cell proves enhanced capacity retention (76.62% vs 58.58% after 500 cycles at 0.5 C) as well. The thermal safety of the NCM523-PSC cathode-based pouch cell is also significantly improved, with the critical temperature of thermal safety T 1 (the beginning temperature of obvious self-heating temperature) and thermal runaway temperature T 2 increased by 60.18 and 44.59 °C, respectively. Mechanistic studies show that the PSC layer has multiple effects as a passivation layer such as isolation of electrode-electrolyte contact, oxygen release suppression, solvation structure tuning, and the decomposition of carbonate solvents as well as LiPF 6 inhibition. This work provides a new path for a cost-effective and scalable design of electrode decoration with synergistic safety-electrochemical kinetics enhancement.

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 -1 and a lithium-ion transference number of 0.37 are exhibited. Symmetrical lithium cells with IL-GPE retain stable cycling even after 3000 h under 0.1 mA cm -2 . IL-GPE exhibits good compatibility toward lithium metal, yielding excellent long-term electrochemical kinetic stability. IL-GPE induces the formation of a uniform and robust SEI layer, inhibiting the growth of lithium dendrites and improving the rate performance and cycle stability. Furthermore, Li/LiFePO 4 cells exhibit a specific capacity of 63 mA h g -1 after 150 cycles at 5.0 C, with a capacity retention of 90.2%. It is foreseen that this GPE is a promising candidate to enhance the safety of high-performance lithium metal batteries.

Porous silicon-based anode materials have gained much interest because the porous structure can effectively accommodate volume changes and release mechanical stress, leading to improved cycling performance. Magnesiothermic reduction has emerged as an effective way to convert silica into porous silicon with a good electrochemical performance. However, corrosive HF etching is normally a mandatory step to improve the electrochemical performance of the as-synthesized silicon, which significantly increases the safety risk. This has become one of the major issues that impedes practical application of the magnesiothermic reduction synthesis of the porous silicon anode. Here, a facile HF-free method is reported to synthesize macro-/mesoporous silicon with good cyclic and rate performance by simply increasing the reduction temperature from 700 °C to 800 °C and 900 °C. The mechanism for the structure change resulting from the increased temperature is elaborated. A finite element simulation indicated that the 3D continuous structure formed by the magnesiothermic reduction at 800 °C and 900 °C could undertake the mechanical stress effectively and was responsible for an improved cyclic stability compared to the silicon synthesized at 700 °C., Competing Interests: There are no conflicts of interest to declare.

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 0.85 Co 0.1 Mn 0.05 O 2 (NCM) is developed where we use ethanol to disperse the nanosized LiBO 2 to form the sol and adopt tetrahydrofuran (THF) as antisolvent to prepare the cluster of nanoparticles to be coated on the surface of NCM. The coating thickness can be tuned through the THF addition amount. The LiBO 2 nanorod deposition is formed as well over the crack of the NCM cathode, likely acting as a patch to repair the original defect of the intrinsic crack. The uniform LiBO 2 nanospherical particle coating together with LiBO 2 nanorod wrapping provides a double protection against electrolytes. Compared with the raw material, LiBO 2 -coated LiNi 0.85 Co 0.1 Mn 0.05 O 2 (LiBO 2 -coated NCM) exhibits a high initial Coulombic efficiency of 90.3% at 0.2 C between 2.8 and 4.3 V vs Li + /Li, a superior rate capability, enhanced fast charge property at 3 C, and restricted microcrack formation. This simple in-site modification and repairing technology guarantees a good mechanical integrity of the polycrystalline Ni-rich cathode.

Nanosized silicon has attracted considerable attentions as a new-generation anode material for lithium-ion batteries (LIBs) due to its exceptional theoretical capacity and reasonable cyclic stability. However, serious side reactions often take place at the nanosized silicon/electrolyte interface in LIBs, where critical electrochemical properties such as initial Coulombic efficiency (ICE) are compromised. On the basis of this feature, a new method is developed to synthesize nanosilicon-based particles in a facile, scalable way, which are endowed with the function of prelithiation and storage stability in air. A semisolid lithium rechargeable flow battery (SSFB) technology is used for the first time to convert the micrometer-sized silicon raw material into an amorphous-nanosilicon-based material (ANSBM), as a result of the pulverization process induced by the repeated lithiation/delithiation cycles. The particle size is successfully reduced from 1-4 μm to around 30 nm after cycles in the flow battery. Bulk functionalization of the nano silicon is introduced by the unbalanced lithiation/delithiation cyclic process, which endows ANSBM with a unique prelithiation capability universally applicable to different anode systems such as nanosized Si, SiO x , and graphite, as evidenced by the significantly improved ICEs. Superior air stability (10% relative humidity) is exhibited by ANSBM due to surface functionalization by the stable interfacial layer encapsulated by electron-conductive carbon. The outcome of this work provides a promising way to synthesize dual-functionalized nano silicon with good electrochemical performance in terms of improved capacity and increased initial Coulombic efficiency when it is composited with other typical anode materials.

As a promising alternative as lithium-ion anode, niobium dioxide appeals to researchers due to high theoretical capacity and good electron conductivity. However, rarely work about NbO 2 based high performance anode is reported. Here, NbO 2 nanoparticles emcoated in continuous carbon matrix is constructed through CO 2 /H 2 coupling treatment. CO 2 activation introduces unique carbon emcoating structure, which builds interconnected electron conductive network with low carbon content. Furthermore, crystallographic phase of NbO 2 is enhanced during H 2 treatment, which increases the lithium storage ability. Electrochemical performance of NbO 2 anodes is significantly improved based on the carbon emcoating structure. A high reversible capacity of 391 mAh g -1 is retained after 350 cycles at 0.2 C. Additionally, at a current density of 1 A g -1 , the reversible capacity reaches 139 mAh g -1 . Compared with conventional NbO 2 /C nanohybrids, the lithium diffusion coefficient of carbon-emcoated sample shows improvement of three orders of magnitude. Moreover, the in situ XRD investigation shows a reversible lithium insertion behaviour with a limited volume change., (© 2022 Wiley-VCH GmbH.)

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 0.5 Co 0.2 Mn 0.3 O 2 (NCM 523) particle surface via an in situ cross-linking reaction between hydroxy-terminated PDMS and methyl trimethoxy silane promoted by moisture at ambient conditions (MPDMS). Improved electrochemical performance is achieved with the MPDMS binder in terms of reversible capacity (201 vs 185 mAh·g -1 at 0.2C), capacity retention (80 vs 68%, after 300 cycles at 1C), and rate performance (55.6% increase at 5C), as demonstrated by the NCM 523||Li half-cell. The NCM 523||graphite full-cell also shows improved performance at 4.6 V (147 vs 128 mAh·g -1 , 82 vs 76%, after 200 cycles at 1C). The mechanism studies indicate that MPDMS exerts multiple effects, including cathode surface passivation, solvation structure tuning, electrolyte uptake enhancement, and mechanical stress relief. This work provides an inspiring route to realize high-voltage application of lithium-ion battery technology.

Ultrafine SnO 2 /Sn nanoparticles encapsulated into an adjustable meso-/macroporous carbon matrix have been successfully fabricated by the in situ SiO x sacrificial strategy. The control over the void space in the carbon matrix effectively improves the accessibility of the SnO 2 /Sn toward an electrolyte solution. More importantly, the void space also provides an efficient means to accommodate the mechanical stress caused by the volume change of the SnO 2 /Sn over cycles. As a result, the enhanced electrolyte accessibility and suppressed mechanical stress improve the electrochemical performance regarding reversible capacity, cyclic stability, and rate capability. A reversible capacity of 1105 mAh g -1 is still retained after 290 cycles at 200 mAg -1 , and the capacity still can keep at 107 mAh g -1 at a high current density of 10 A g -1 .

Increasing the working voltage of lithium-ion batteries (LIBs) is an efficient way to increase energy density. However, high voltage triggers excessive electrolyte decomposition at the electrode-electrolyte interfaces, where the electrochemical performance such as cyclic stability and rate capability is seriously deteriorated. A new synergistic positive and passive approach is proposed in this work to construct a stable electrode-electrolyte interface at high voltage. As a positive approach, inorganic lithium sulfide salt (Li 2 S) is used as an electrolyte additive to build a stable cathode electrolyte interface (CEI) at the LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cathode surface. In a passive way, acetonitrile (AN) is applied as a solvent additive to suppress oxidative decomposition of a carbonate electrolyte via preferential solvation with a lithium ion. Because of the synergistic interaction between the positive and passive approaches, the cyclic stabilities of NCM523/Li cells improved with a tiny amount of Li 2 S (0.01 mg mL -1 ) and AN (0.5 vol %). The capacity retention increased to 80.74% after 200 cycles compared to the cells with the blank electrolyte (67.98%) and AN-containing electrolyte (75.8%). What is more, the capacity retention of the NCM523/graphite full cell is increased from 65 to 81% with the addition of the same amount of Li 2 S and AN after 180 cycles. The mechanism is revealed on the basis of the theoretical calculations and various characterizations. The products derived from the preferential adsorption and oxidation of Li 2 S on the surface of NCM523 effectively increase the content of inorganic ingredients. However, the presence of AN prevents oxidation of the solvent. This study provides new principle guiding studies on a high-voltage lithium-ion battery with excellent electrochemical performance.

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 LiNi 0.5 Co 0.2 Mn 0.3 O 2 (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.

Gel polymer electrolytes (GPEs) have attracted ever-increasing attention in Li-ion batteries, due to their great thermal stability and excellent electrochemical performance. Here, a flexible poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP)-based GPE doped with an appropriate proportion of the PEO and SiO 2 is developed through a universal immersion precipitation method. This porous PVDF-HFP-PEO-SiO 2 GPE with high ionic conductivity and lithium-ion transference number ( t Li + ) can enhance the electrochemical performance of LiFePO 4 cells, leading to superior rate capability and excellent cycling stability. Moreover, the PVDF-HFP-PEO-SiO 2 GPE effectively inhibits the lithium dendrite growth, thereby improving the safety of Li-ion batteries. In view of the simplicity in using the gel polymer electrolyte, it is believed that this novel GPE can be used as a potential candidate for high-performance Li-ion batteries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Antimony (Sb) has been regarded as one of the most promising anode materials for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) and attracted much attention in recent years. Alleviating the volumetric effect of Sb during charge and discharge processes is the key point to promote Sb-based anodes to practical applications. Carbon dioxide (CO 2 ) activation is applied to improve the rate performance of the Sb/C nanohybrid anodes caused by the limited diffusion of Li/Na ions in excessive carbon components. Based on the reaction between CO 2 and carbon, CO 2 activation can not only reduce the excess carbon content of the Sb/C nanohybrid but also create abundant mesopores inside the carbon matrix, leading to enhanced rate performance. Additionally, CO 2 activation is also a fast and facile method, which is perfectly suitable for the fabrication system we proposed. As a result, after CO 2 activation, the average capacity of the Sb/C nanohybrid LIB anode is increased by about 18 times (from 9 mA h g -1 to 160 mA h g -1 ) at a current density of 3300 mA g -1 . Moreover, the application of the CO 2 -activated Sb/C nanohybrid as a SIB anode is also demonstrated, showing good electrochemical performance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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 (CF 3 SO 3 H). Through a low-concentration and low-temperature CF 3 SO 3 H 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.

Silicon is regarded as one of the most promising next generation lithium-ion battery anodes due to its exceptional theoretical capacity, appropriate voltage profile, and vast abundance. Nevertheless, huge volume expansion and drastic stress generated upon lithiation cause poor cyclic stability. It has been one of the central issues to improve cyclic performance of silicon-based lithium-ion battery anodes. Constructing hierarchical macro-/mesoporous silicon with a tunable pore size and wall thickness is developed to tackle this issue. Rational structure design, controllable synthesis, and theoretical mechanical simulation are combined together to reveal fundamental mechanisms responsible for an improved cyclic performance. A self-templating strategy is applied using Stöber silica particles as a templating agent and precursor coupled with a magnesiothermic reduction process. Systematic variation of the magnesiothermic reduction time allows good control over the structures of the porous silicon. Finite element mechanical simulations on the porous silicon show that an increased pore size and a reduced wall thickness generate less mechanical stress in average along with an extended lithiation state. Besides the mechanical stress, the evolution of strain and displacement of the porous silicon is also elaborated with the finite element simulation.

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., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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.

Substantial effort has been devoted to both scientific and technological developments of wearable, flexible, semitransparent, and sensing electronics (e.g., organic/perovskite photovoltaics, organic thin-film transistors, and medical sensors) in the past decade. The key to realizing those functionalities is essentially the fabrication of conductive electrodes with desirable mechanical properties. Conductive polymers (CPs) of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have emerged to be the most promising flexible electrode materials over rigid metallic oxides and play a critical role in these unprecedented devices as transparent electrodes, hole transport layers, interconnectors, electroactive layers, or motion-sensing conductors. Here, the current status of research on PEDOT:PSS is summarized including various approaches to boosting the electrical conductivity and mechanical compliance and stability, directly linked to the underlying mechanism of the performance enhancements. Along with the basic principles, the most cutting edge-progresses in devices with PEDOT:PSS are highlighted. Meanwhile, the advantages and plausible problems of the CPs and as-fabricated devices are pointed out. Finally, new perspectives are given for CP modifications and device fabrications. This work stresses the importance of developing CP films and reveals their critical role in the evolution of these next-generation devices featuring wearable, deformable, printable, ultrathin, and see-through characteristics., Competing Interests: The authors declare no conflict of interest., (© 2019 The Authors. Published by WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.)

Super-small sized TiO 2 nanoparticles are in situ co-composited with carbon and nickel nanoparticles in a facile scalable way, using difunctional methacrylate monomers as solvent and carbon source. Good control over crystallinity, morphology, and dispersion of the nanohybrid is achieved because of the thermosetting nature of the resin polymer. The effects of the nickel nanoparticle on the composition, crystallographic phase, structure, morphology, tap density, specific surface area, and electrochemical performance as both lithium-ion and sodium-ion battery anodes are systematically investigated. It is found that the incorporation of the in situ formed nickel nanoparticles with certain content effectively enhances the electrochemical performance including reversible capacities, cyclic stability and rate performance as both lithium-ion and sodium-ion battery anodes. The experimental I-V profiles at different temperatures and theoretical calculations reveal that the charge carriers are accumulated in the amorphous carbon regions, which act as scattering centers to the carriers and lower the carrier mobility for the composite. With increasing nickel content, the mobility of the charge carriers is significantly increased, while the number of the charge carriers maintains almost constant. The nickel nanoparticles provide extra pathways for the accumulated charge, leading to reduced scatterings among the charge carriers and enhanced charge-carrier transportation., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reversible anionic (oxygen) redox in lithium-rich cathode oxides has been becoming a blooming research topic to further boost the energy density in lithium-ion batteries. There are numerous experimental observations and theoretical calculations to illustrate the importance of defects on anionic redox activity, but how the defects on the surface and bulk control the kinetics of anionic redox is not well understood. Here, we uncover this intriguing ambiguity on the correlation among defects states, Li-ion diffusion, and oxygen redox reaction. It is found that the surface-defective microstructure has fast Li-ion diffusion to achieve superior cationic redox activities/kinetics, whereas the bulk-defective microstructure corresponds to a slow Li-ion diffusion to result in poor cationic redox activities/kinetics. By contrast, both surface and bulk defects can be of benefit to the enhancement of oxygen redox activities/kinetics. Moreover, a positive correlation is also established among charge-transfer resistance, interface reaction charge-transfer activation energy, and oxygen redox activity in these electrode materials. This study on defect-anionic activity provides a new insight for controlling anionic redox reaction in lithium-rich cathode materials for real-world application.

An aluminum anode with pre-constructed two-layer conductive buffers was prepared to restrict the expanding Al-Li alloy inside, and provide continuous electron pathways for promising electrical contact. The full cell demonstrates superior cycling stability (0.0352% capacity decay per cycle for 400 cycles at 0.2C) and outstanding rate capability.

Electrochemical prelithiation is a facile, effective and extensively used method to improve the initial coulombic efficiency of SiO. However, much less research attention has been devoted to prelithiation effect on initial several cycles. Here, we introduce a new perspective to evaluate the prelithiation behaviors, which could understand in depth the electrochemical prelithiation behaviors and their effects on the following two cycles. Then X-ray photoelectron spectroscopy was further performed to pinpoint the reaction products. It has been found that the quantity of irreversible Li 4 SiO 4 , Li 2 O and SEI (Li 2 CO 3 and LiF) and reversible Li x Si are increasing as the prelithiation time extending. When the prelithiation time extending over 20 min, only alloy reaction of Si has been revealed. The regeneration of SEI discloses at least 7% capacity loss in the first cycle which depends on the prelithiated time. However, the reformation of SEI in the second cycles reveals 3% capacity loss. Because the coulombic efficiencies are independent on prelithiated time in the second cycle which indicates only one discharge/charge cycle is enough to form integrated SEI and adequate irreversible Li 4 SiO 4 and Li 2 O except part of unreactive SiO x ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Li 4 Ti 5 O 12 (LTO) is regarded as a promising lithium-ion battery anode due to its stable cyclic performance and reliable operation safety. The moderate rate performance originated from the poor intrinsic electron and lithium-ion conductivities of the LTO has significantly limited its wide applications. A facile scalable synthesis of hierarchical Li 4 Ti 5 O 12 /C nanohybrids with supersmall LTO nanoparticles (ca. 17 nm in diameter) homogeneously embedded in the continuous submicrometer-sized carbon matrix is developed. Difunctional methacrylate monomers are used as solvent and carbon source to generate TiO 2 /C nanohybrid, which is in situ converted to LTO/C via a solid-state reaction procedure. The structure, morphology, crystallinity, composition, tap density, and electrochemical performance of the LTO/C nanohybrid are systematically investigated. Comparing to the control sample of the commercial LTO composited with carbon, the reversible specific capacity after 1000 cycles at 175 mA g -1 and rate performance at high current densities (875, 1750, and 3500 mA g -1 ) of the Li 4 Ti 5 O 12 /C nanohybrid have been significantly improved. The enhanced electrochemical performance is due to the unique structure feature, where the supersmall LTO nanoparticles are homogeneously embedded in the continuous carbon matrix. Good tap density is also achieved with the LTO/C nanohybrid due to its hierarchical micro-/nanohybrid structure, which is even higher than that of the commercial LTO powder.

Silicon (Si) has been regarded as one of the most promising anodes for next-generation lithium-ion batteries (LIBs) due to its exceptional capacity, appropriate voltage profile, and reliable operation safety. However, poor cyclic stability and moderate rate performance have been critical drawbacks to hamper the practical application of Si-based anodes. It has been one of the central issues to develop new strategies to improve the cyclic and rate performance of the Si-based lithium-ion battery anodes. In this work, super-small metal nanoparticles (2.9 nm in diameter) are in situ synthesized and homogeneously embedded in the in situ formed nitrogen-doped carbon matrix, as demonstrated by the Si/Ag/C nanohybrid, where epoxy resin monomers are used as solvent and carbon source. With tiny amount of silver (2.59% by mass), the Si/Ag/C nanohybrid exhibits superior rate performance compared to the bare Si/C sample. Systematic structure characterization and electrochemical performance tests of the Si/Ag/C nanohybrids have been performed. The mechanism for the enhanced rate performance is investigated and elaborated. The temperature-dependent I-V behavior of the Si/Ag/C nanohybrids with tuned silver contents is measured. Based on the model, it is found that the super-small silver nanoparticles mainly increase charge carrier mobility instead of the charge carrier density in the Si/Ag/C nanohybrids. The evaluation of the total electron transportation length provided by the silver nanoparticles within the electrode also suggests significantly enhanced charge carrier mobility. The existence of tremendous amounts of super-small silver nanoparticles with excellent mechanical properties also contributes to the slightly improved cyclic stability compared to that of simple Si/C anodes.

Fluorinated electrolytes based on fluoroethylene carbonate (FEC) have been considered as promising alternative electrolytes for high-voltage and high-energy capacity lithium-ion batteries (LIBs). However, the compatibility of the fluorinated electrolytes with graphite negative electrodes is unclear. In this paper, we have systematically investigated, for the first time, the stability of fluorinated electrolytes with graphite negative electrodes, and the result shows that unlike the ethylene carbonate (EC)-based electrolyte, the FEC-based electrolyte (EC was totally replaced by FEC) is incapable of forming a protective and effective solid electrolyte interphase (SEI) that protects the electrolyte from runaway reduction on the graphite surface. The reason is that the lowest unoccupied molecular orbital energy levels are also lowered by the introduction of fluorine into the solvent, and the FEC solvent has poorer resistance against reduction, leading to instability on the graphite negative electrode. To tackle this problem, two lithium salts of lithium bis(oxalato)borate and lithium difluoro(oxalato)borate (LiDFOB) have been investigated as negative-electrode film-forming additives. Incorporation of only 0.5 wt % LiDFOB to a FEC-based electrolyte [1.0 M LiPF 6 in 3:7 (FEC-ethyl methyl carbonate)] results in excellent cycling performance of the graphite negative electrode. This improved property originates from the generation of a thinner and better quality SEI film with little LiF by the sacrificial reduction of the LiDFOB additive on the graphite negative electrode surface. On the other hand, this additive can stabilize the electrolyte by scavenging HF. Meanwhile, the incorporated LiDFOB additive has positive influence on the interphase layer on the positive electrode surface and significantly decreases the amount of HF formation, finally leading to improved cycling stability and rate capability of LiNi 0.5 Mn 1.5 O 4 electrodes at a high cutoff voltage of 5 V. The data demonstrate that the LiDFOB additive not only exhibits a superior compatibility with graphite but also improves the electrochemical properties of high-voltage spinel LiNi 0.5 Mn 1.5 O 4 positive electrodes considerably, confirming its potential as a prospective, multifunctional additive for 5 V fluorinated electrolytes in high-energy capacity lithium-ion batteries (LIBs)., Competing Interests: The authors declare no competing financial interest.

Separators with high security, reliability, and rate capacity are in urgent need for the advancement of high power lithium ion batteries. The currently used porous polyolefin membranes are critically hindered by their low thermal stability and poor electrolyte wettability, which further lead to low rate capacity. Here we present a novel promising porous polybenzimidazole (PBI) membrane with super high thermal stability and electrolyte wettability. The rigid structure and functional groups in the PBI chain enable membranes to be stable at temperature as high as 400 °C, and the unique flame resistance of PBI could ensure the high security of a battery as well. In particular, the prepared membrane owns 328% electrolyte uptake, which is more than two times higher than commercial Celgard 2325 separator. The unique combination of high thermal stability, high flame resistance and super high electrolyte wettability enable the PBI porous membranes to be highly promising for high power lithium battery.

As rechargeable Li-ion batteries have expanded their applications into on-board energy storage for electric vehicles, the energy and power must be increased to meet the new demands. Li-rich layered oxides are one of the most promising candidate materials; however, it is very difficult to make them compatible with high volumetric energy density and power density. Here, we develop an innovative approach to synthesize three-dimensional (3D) nanoporous Li-rich layered oxides Li[Li 0.144 Ni 0.136 Co 0.136 Mn 0.544 ]O 2 , directly occurring at deep chemical delithiation with carbon dioxide. It is found that the as-prepared material presents a micrometer-sized spherical structure that is typically composed of interconnected nanosized subunits with narrow distributed pores at 3.6 nm. As a result, this unique 3D micro-/nanostructure not only has a high tap density over 2.20 g cm -3 but also exhibits excellent rate capability (197.6 mA h g -1 at 1250 mA g -1 ) as an electrode. The excellent electrochemical performance is ascribed to the unique nanoporous micro-nanostructures, which facilitates the Li + diffusion and enhances the structural stability of the Li-rich layered cathode materials. Our work offers a comprehensive designing strategy to construct 3D nanoporous Li-rich layered oxides for both high volumetric energy density and power density in Li-ion batteries.

Porous silicon has found wide applications in many different fields including catalysis and lithium-ion batteries. Three-dimensional hierarchical macro-/mesoporous silicon is synthesized from zero-dimensional Stöber silica particles through a facile and scalable magnesiothermic reduction process. By systematic structure characterization of the macro-/mesoporous silicon, a self-templating mechanism governing the formation of the porous silicon is proposed. Applications as lithium-ion battery anode and photocatalytic hydrogen evolution catalyst are demonstrated. It is found that the macro-/mesoporous silicon shows significantly improved cyclic and rate performance over the commercial nanosized and micrometer-sized silicon particles. After 300 cycles at 0.2 A g -1 , the reversible specific capacity is still retained as much as 959 mAh g -1 with a high mass loading density of 1.4 mg cm -2 . With the large current density of 2 A g -1 , a reversible capacity of 632 mAh g -1 is exhibited. The coexistence of both macro- and mesoporous structures is responsible for the enhanced performance. The macro-/mesoporous silicon also shows superior catalytic performance for photocatalytic hydrogen evolution compared to the silicon nanoparticles.

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas-solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g(-1) with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g(-1) still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

A new facile scalable method has been developed to synthesize silicon oxycarbide (SiOC)/carbon nanohybrids using difunctional dental methacrylate monomers as solvent and carbon source and the silane coupling agent as the precursor for SiOC. The content (from 100% to 40% by mass) and structure (ratio of disordered carbon over ordered carbon) of the free carbon matrix have been systematically tuned by varying the mass ratio of methacryloxypropyltrimethoxysilane (MPTMS) over the total mass of the resin monomers from 0.0 to 6.0. Compared to the bare carbon anode, the introduction of MPTMS significantly improves the electrochemical performance as a lithium-ion battery anode. The initial and cycled discharge/charge capacities of the SiOC/C nanohybrid anodes reach maximum with the MPTMS ratio of 0.50, which displays very good rate performance as well. Detailed structures and electrochemical performance as lithium-ion battery anodes have been systematically investigated. The structure-property correlation and corresponding mechanism have been discussed.

A new strategy to synthesize hierarchical, porous titania/carbon (TiO2/C) hybrid microspheres via solvothermal reaction in N,N'-dimethyl formamide (DMF) has been developed. In situ formed polystyrene (PS) colloids have been used as templating agent and carbon source, through which TiO2/PS microspheres with a diameter of ca. 1 μm are built by packed TiO2 nanoparticles of tens of nanometers. The TiO2/PS microspheres are converted to TiO2/C microspheres with different amounts of carbon under controlled calcination condition. The mechanism investigation unveils that the introduction of concentrated HCl creates surface tension between PS and DMF, leading to the formation of PS colloids in solution. The solvothermal treatment further promotes the formation of PS colloids and integration of the titania nanoparticles within the PS colloids. The morphology, crystallinity, nature and content of carbon, UV-Vis absorption, carbon doping, pore size distribution, pore volume, and BET surface area of the TiO2 microspheres with different amounts of carbon have been measured. The applications of the TiO2/C hybrid microspheres as photo catalyst for water splitting and lithium-ion battery anode have been demonstrated. Superior photo catalytic activity for hydrogen conversion under both full spectrum and visible light illumination compared to commercial P25 has been observed for the TiO2/C microspheres with 2 wt% of carbon. Besides, the TiO2/C microspheres with 8 wt% of carbon as lithium-ion battery anode showed a much higher capacity than the bare TiO2 microsphere anode. The origin for the enhanced performance as photo catalyst and lithium-ion battery anode is discussed., (Copyright © 2016 Elsevier Inc. All rights reserved.)

A facile scalable synthesis of TiO2/C nanohybrids inspired by polymeric dental restorative materials has been developed, which creates ultrasmall TiO2 nanoparticles homogeneously embedded in the carbon matrix. The average size of the nanoparticles is tuned between about 1 and 5 nm with the carbon content systematically increased from 0% to 65%. Imaging analysis and a scattering technique have been applied to investigate the morphology of the TiO2 nanoparticles. The composition, nature of carbon matrix, crystallinity, and tap density of the TiO2/C nanohybrids have been studied. The application of the TiO2/C nanohybrids as lithium-ion battery anode is demonstrated. Unusual discharge/charge profiles have been exhibited, where characteristic discharge/charge plateaus of crystalline TiO2 are significantly diminished. The tap density, cyclic capacities, and rate performance at high current densities (10 C, 20 C) of the TiO2/C nanohybrid anodes have been effectively improved compared to the bare carbon anode and the TiO2/C nanohybrids with larger particle size.

A lithium-rich cathode material Li1.14 Mn0.54 Ni0.14 Co0.14 O2 (LNMCO) is prepared by a co-precipitation method. The issue of voltage decay in long-term cycling is largely eliminated by control of the charge-discharge voltage range. The LNMCO material exhibits 9.8 % decay in discharge voltage over 200 cycles between 2.0-4.6 V, during which the working voltage decays significantly, from 3.57 V to 3.22 V. The decay was decelerated by a factor of six by using a voltage window of 2.0-4.4 V, from 3.53 V to 3.47 V. IR and Raman spectra reveal that the transformation of layered structure to spinel is significantly retarded under 2.0-4.4 V cycling conditions. Transmission electron microscopy (TEM) was also applied for examining phase change in an individual particle during cycling, showing that the spinel phase occurs both at 2.0-4.6 V and at 2.0-4.4 V, but is not dominant in the latter. Normalization of Li can remove the additional impact on the voltage decay which is brought by different amounts of Li intercalation. The mechanism of no voltage decay at 2.0-4.4 V cycling is raised and electrochemical impedance spectrum data also support the hypothesis., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Separators with high reliability and security are in urgent demand for the advancement of high performance lithium ion batteries. Here, we present a new and practical porous membrane with three-dimension (3D) heat-resistant skeleton and high curvature pore structure as a promising separator candidate to facilitate advances in battery safety and performances beyond those obtained from the conventional separators. The unique material properties combining with the well-developed structural characteristics enable the 3D porous skeleton to own several favorable properties, including superior thermal stability, good wettability with liquid electrolyte, high ion conductivity and internal short-circuit protection function, etc. which give rise to acceptable battery performances. Considering the simply and cost-effective preparation process, the porous membrane is deemed to be an interesting direction for the future lithium ion battery separator.

Electrode films fabricated with lithium-rich layered 0.3Li2MnO3-0.7LiNi5/21Co5/21Mn11/21O2 cathode materials have been successfully modified with ZnO coatings via a reactive magnetron sputtering (RMS) process for the first time. The morphology and chemical composition of coating films on the electrodes have been in deep investigated by transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS) characterizations. The results clearly demonstrate that ZnO film coatings are ultrathin, dense, uniform, and fully covered on the electrodes. The RMS-2 min (deposition time) coated electrode exhibits much higher initial discharge capacity and coulombic efficiency with 316.0 mAh g(-1) and 89.1% than that of the pristine electrode with 283.4 mAh g(-1) and 81.7%. In addition, the discharge capacity also reaches 256.7 and 187.5 mAh g(-1) at 0.1 and 1.0 C-rate, as compared to that of 238.4 and 157.8 mAh g(-1) after 50 cycles. The improved electrochemical performances of RMS-coated electrodes are ascribed to the high-quality ZnO film coatings that reduce charge transfer resistance and effectively protect active material from electrolyte oxidation.

A green facile scalable method inspired by polymeric dental restorative composite is developed to synthesize TiO2/carbon nanocomposites for manipulation of the intercalation potential of TiO2 as lithium-ion battery anode. Poorly crystallized TiO2 nanoparticles with average sizes of 4-6 nm are homogeneously embedded in carbon matrix with the TiO2 mass content varied between 28 and 65%. Characteristic discharge/charge plateaus of TiO2 are significantly diminished and voltage continues to change along with proceeding discharge/charge process. The tap density, gravimetric and volumetric capacities, and cyclic and rate performance of the TiO2/C composites are effectively improved.

Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li(+)/Na(+) mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li(+) insertion/extraction reaction, and the other mainly relates to Na(+) extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg(-1) and 25 Wh kg(-1) based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li(+) and Na(+) due to its specific mechanism unlike the traditional "rocking-chair" lithium-ion batteries. Hence, the Li(+)/Na(+) mixed-ion batteries offer promising applications in energy storage and Li(+)/Na(+) separation.