Long Cycle Life Research Articles

Consecutive core–shell SP@PDA-d-δ-MnO2 cathode material for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) based on Zn/MnO2 are highly attractive owing to their low cost, safety, environmental benignity, and elemental abundance. However, the MnO2 cathode is still insufficiently reversible at a high energy density and under long-life cycling owing to its dissolution–redeposition and low electronic conductivity. In this study, core–shell-structured SP@PDA-d-δ-MnO2 with consecutive super p cores and an evenly distributed δ-MnO2 shell was designed and prepared. SP@PDA-d-δ-MnO2, as a cathode material for aqueous ZIBs, shows a high specific capacity, moderate rate, and cycling properties in a 2.0 M ZnSO4 aqueous electrolyte. We determined that the continuously connected conductive carbon inside MnO2 facilitates electron conduction in the cathode material and provides a conductive matrix for the electrodeposition of Mn2+, which contribute to the performance of aqueous ZIBs.

Longer cycle life and higher discharge voltage of a small molecular indanthrone resulting from the extended conjugated framework

Organic cathodes have attracted wide attentions owing to their worthful advantages including higher capacity, abundant reserves and designable structure. However, significant dissolution of active organic materials hinders their practical applications in lithium-ion batteries (LIBs). Extending the conjugated framework in which intermolecular interactions play a crucial role, is an efficient strategy to inhibit the dissolution. Herein, an organic molecule with extended conjugated framework, indanthrone (IDT), is reported for LIBs. The rich carboxyl groups (CO) ensure the high capacity for redox reactions, which is hence utilized as cathodic active centers. Moreover, the presence of CO and amidogen resulted in plentiful intermolecular interactions, leading to insolubility and high stability. The rich functional groups also promote the chelation of oxygen and nitrogen with Li-ion and hence benefit their storage. A specific capacity of 238 mAh g−1 has been achieved for IDT-based cathodes at 0.2C, and a capacity of over 200 mAh g−1 is retained after 1000 cycles with a decay rate of only ∼0.014% per-cycle. It is worth mentioning that there is a visible increase in voltage platform during cycling. The structure design of extending the conjugated framework endows the battery performance with longer cycle life and higher energy density.

Engineering Lithiophilic Silver Sponge Integrated with Ion-Conductive PVDF/LiF Protective Layer for Dendrite-Free and High-Performance Lithium Metal Batteries

Although lithium metal anode has attracted much attention as the “Holy Grail” because of its high specific capacity and the lowest reduction potential, its practical applications are largely hindered by the short circuit resulted from the unfavorable growth of lithium dendrites and the unstable interface caused by the parasitic reactions between the highly active lithium metal and the nonaqueous liquid electrolyte. Herein, a multifunctional bilayer structure integrating the spongelike lithiophilic Ag layer and the ion-conductive polyvinylidene difluoride (PVDF)/LiF layer is fabricated for high-performance lithium metal anode. The porous lithiophilic Ag sponge layer provides abundant lithium nucleation sites and deposition space for the uniform growth of lithium, thereby endowing the compact deposition of lithium without the overgrowth of lithium dendrites. The ion-conductive and electronically insulating PVDF/LiF layer improves the lithium-ion transfer and guarantees the interface stability by suppressing the parasitic reactions between the lithium metal and the nonaqueous electrolyte. Moreover, the artificial PVDF/LiF layer can avoid the probability of unfavorable contact between dendrites and the cathode, even though the spongelike Ag layer is “swollen” by the Li metal. Therefore, the PVDF/LiF–Ag@Cu||Li half cell exhibits a more stable average Coulombic efficiency of ∼98.2% and a longer cycle life than Cu||Li and Ag@Cu||Li half cells. Additionally, the symmetric cell of PVDF/LiF–Ag@Li||PVDF/LiF–Ag@Li exhibits a longer cycling time without short circuit and still retains a lower polarization of ∼35 mV for at least 700 h than compared samples. The PVDF/LiF–Ag@Li||LiFePO4 full cell exhibits the longest cycle life, the best rate performance, and the highest capacity retention, especially with a high LiFePO4 mass loading of ∼10 mg cm–2.

Self-supporting Biomass Li–S Cathodes Decorated with Metal Phosphides–Higher Sulfur Loading, Better Stability, and Longer Cycle Life

Under the premise of high sulfur loading, how to solve the problems of low capacity, short cycle life, and poor rate performance caused by the dynamics of polysulfide and further exert the advantages of the excellent energy density of Li–S batteries is a hot topic nowadays. Herein, the high-S loading self-supporting biomass Li–S cathodes decorated with metal phosphides (MPx, M = Ni, Co, and Fe) were developed. The cattail, an aquatic plant, was employed as a raw material to prepare a three-dimensional self-supporting carbon matrix (SSC) with excellent flexibility. The complex and fluffy structure of the SSC carrier could effectively alleviate volume variation during the cycle of the battery while loading more sulfur, and its carbon nanotube network with favorable conductivity could also achieve rapid electron transfer. In addition, by combining the calculation results of density functional theory with electrochemical properties, we proved that all three phosphides have a strong adsorption and catalytic effect on polysulfides, while further elaborating the specific functions and behaviors of different metal phosphides in promoting polysulfide conversion. Finally, the MPx@SSC-1150 (M = Ni/Co/Fe) not only possesses high initial discharge capacities (1236.96, 1398.45, and 1240.96 mA h g–1, respectively) under a high load (5.5 mg cm–2) but also ensures excellent long-cycle stability. The work opens feasible avenues for the selection and preparation of compounds for the catalytic conversion of polysulfides in Li–S batteries with high-S loading.

Data-Based Approach to Educational Programs Quality Management

The purpose of this article is to describe and justify the approach to assessing the quality of educational programs that have been developed and tested at ITMO University since 2019. The article presents the main indicators of assessment and the results of testing this approach at the university. The main unit of quality is an educational program, as it has a long-life cycle and meets the needs of most stakeholders of the educational organization. Taking into account all the features of an educational program, the authors propose a comprehensive set of indicators to assess its quality, which makes it possible to objectively manage it data-based. In conclusion, for completing the task of analyzing the life cycle of an educational program, the authors present an internal rating of educational programs, concise examples of recommendations based on its results. The advantages of the approach to managing educational programs are described, and ways for further development are presented. The article may be of interest to the managers and management teams of institutions of higher education, as well as to the researchers in this field.

Towards commercializing the “made in Sri Lanka” Lithium-ion batteries

Energy plays a crucial role in the human civilization. Today, the whole world is facing an energy crisis with the rising energy demand, fluctuating prices, supply constraints, and environmental concerns. While renewable energy resources can alleviate some of the global energy security challenges, their intermittency and non-dispatchability can cause problems. Therefore, robust energy storage systems (ESSs) are also important in the sustainable energy transition. Among the many ESS technologies, battery energy storage system (BESS) is one of the most popular methods, as they can be easily adapted to distributed applications and quickly deployed. The Lithium-ion battery (LIB) has significant benefits over other batteries. They have a longer life cycle, higher energy density, faster charge and discharge cycles, quick manufacturing and deploying processes, and lower maintenance requirements. LIB technology is one of the best candidates for a BESS, and its market share and R&D efforts are growing fast [1], [2]. Over the last 30 years, the LIB has come a long way with various improvements to make it more compact and safe while simultaneously enhancing the energy density and cycle life.

Study of the cross-transportation of V(II)/V(III) in vanadium flow batteries based on online monitoring of nonlinear absorption spectra

In vanadium flow batteries (VFBs), the concentration and volume imbalances cause continual capacity loss during the long charge/discharge cycles due to the accumulation of vanadium cross-transportation. To detect these imbalances, the total vanadium concentration (TVC) and state of charge (SOC) need to be simultaneously monitored online. In this work, the absorption spectra of the negative electrolyte are calibrated to further obtain empirical formulas for the absorbance at 605 nm and 640 nm versus the concentrations of V(II) and V(III). Real-time TVC and SOC can be obtained by solving the equations formed by the empirical equations during online monitoring. Compared with the potentiometric titration, this method demonstrates high accuracy and resolution. Based on this, the specific behavior of vanadium cross-transportation during 200 charge/discharge cycles is studied and confirmed that the vanadium is transported from the positive electrolyte to the negative electrolyte during charging and vice versa during discharging. Vanadium cross-transportation amount and its contribution to the capacity loss are further quantified. The absorption spectra online monitoring method proves to be an excellent way to detect the imbalances of negative electrolyte and is expected to effectively guide the design of VFBs with higher capacity and longer cycle life.

A thermoregulating separator based on black phosphorus/MOFs heterostructure for thermo-stable lithium-sulfur batteries

Apart from the traditional problems of shuttling effect of polysulfides and unmanageable growth of lithium dendrites, lithium-sulfur batteries (LSBs) could also unavoidably undergo drastic changes in internal temperature for high-rate charging/discharging process, which could shorten the cycle lifespan of the batteries. Herein, a novel asymmetric thermoregulating separator based on MOFs/black phosphorus heterostructure (UiO66@BP) was developed to address the issues above-mentioned effectively. The asymmetric separator was fabricated by encapsulating the phase-change material of paraffin wax (PW) in polyacrylonitrile nanofibers followed by vacuum filtration of UiO66@BP hybrids onto the surface of the electrospun separator. The block-adsorb-catalyze process of polysulfides in UiO66@BP heterostructure interface contributed to the smooth and effective conversion of the captive polysulfides, therefore the cell exhibited ultralow fading rate of 0.016% per cycle over 1000 cycles, which was comparable to other relative reports of Li-S cells. Moreover, the thermoregulating separator could alleviate the internal temperature rise timely since the melting process of PW could absorb large amounts of heat. The experimental results also showed that the heat absorption and preservation properties of the encapsulated PW endowed the separator with good performance in temperature adjustment, therefore the cells presented smooth and stable cycling stability as well as stable coulomb efficiency compared to none PW-based separator. This work proposed a new insight of phase-change material-based separator contributing to stable solid electrolyte interface and cycling stability of the battery in temperature-varying condition, anticipating its promising application in stable and long-life cycles Li-S batteries.

Iodine-Ion-Assisted Galvanic Replacement Synthesis of Bismuth Nanotubes for Ultrafast and Ultrastable Sodium Storage.

Bismuth (Bi) has emerged as a promising anode material for fast-charging and long-cycling sodium-ion batteries (SIBs). However, its dramatically volumetric variations during cycling will undesirably cause the pulverization of active materials, severely limiting the electrochemical performance of Bi-based electrodes. Constructing hollow nanostructures is recognized as an effective way to resolve the volume expansion issues of alloy-type anodes but remains a great challenge for metallic bismuth. Here, we report a facile iodine-ion-assisted galvanic replacement approach for the synthesis of Bi nanotubes (NTs) for high-rate, long-term and high-capacity sodium storage. The hollow tubular structure effectively alleviates the structural strain during sodiation/desodiation processes, resulting in excellent structural stability; the thin wall and large surface area enable ultrafast sodium ion transport. Benefiting from the structural merits, the Bi NT electrode exhibits extraordinary rate capability (84% capacity retention at 150 A g-1) and outstanding cycling stability (74% capacity retention for 65,000 cycles at 50 A g-1), which represent the best rate performance and longest cycle life among all reported anodes for SIBs. Moreover, when coupled with the Na3(VOPO4)2F cathode in full cells, this electrode also demonstrates excellent cycling performance, showing the great promise of Bi NTs for practical application. A combination of advanced research techniques reveals that the excellent performance originates from the structural robustness of the Bi NTs and the fast electrochemical kinetics during cycling.

Methyl-functionalized hydrangea-like vanadium pentoxide cathode for aqueous zinc ion batteries with high-rate and long-term cycling stability

Vanadium Pentoxide (V 2 O 5 ) is an appealing cathode candidate for Zinc-ion batteries (ZIBs) owing to its modifiable interlayer structure and changeable chemical redox states. However, the extensive practical application is deeply plagued by either poor rate capability or cycling stability performance. Herein, the methyl group decorated V 2 O 5 with hydrangea-like morphology was successfully fabricated by a facile solvothermal method to solve the problem. Such a hydrangea-shaped architecture containing numerous nanosheets is advantageous for the rapid ions/electrons transfer. The extended interlayer distance stemmed from the pillar effect of the methyl-functionalized V 2 O 5 contributes a comparatively steady and rapid Zn 2+ intercalation/deintercalation. When applied in ZIBs, it delivers a superior rate capability (123 mA h g −1 at 4.0 A g −1 ) and an excellent long-life cycling (capacity retention of 112.7 % after 1000 cycles at 4.0 A g −1 ). Electrochemical kinetics investigations of methyl-functionalized V 2 O 5 microsphere show that the capacity is dominantly contributed from pseudocapacitance. As well, mechanism of zinc ion storage has been explored. Such a structural design of electrode materials can be exploited to promote extensive applications of ZIBs in future. Pillaring effect of methyl group in the hydrangea-like V 2 O 5 microsphere ensures the expanded interlayer spacing for advanced Zn storage. • Methyl-functionalized V 2 O 5 is successfully prepared via a simple solvothermal method. • Pillaring effect of methyl group endows the favorable interlayer expansion and structural stability. • Methyl-functionalized V 2 O 5 is a promising cathode material for Zn-ion batteries.

Unveiling the Mystery of Lithium Bis(fluorosulfonyl)imide as a Single Salt in Low-to-Moderate Concentration Electrolytes of Lithium Metal and Lithium-Ion Batteries

This work aims to unveil the mystery about the suitability of using lithium bis(fluorosulfonyl)imide (LiFSI) as a single salt in low-to-moderate concentration electrolytes of Li metal and Li-ion batteries by studying the corrosion behavior of Al and stainless steel (SS) in 3:7 (wt) ethylene carbonate/ethyl methyl carbonate electrolytes. It is found that regardless of LiFSI concentrations (0.8–1.8 m), there is a ∼4.3 V vs Li/Li+ of “threshold potential,” above which Al suffers uncontrollable corrosion. This finding is confirmed in graphite/LiNi0.80Co0.15Al0.05O2 pouch cells, however, none of Li/LiNi0.80Co0.10Mn0.10O2 coin cells can be charged to 4.2 V in the first charge. Post-mortem analysis of the failed coin cells reveals that the failure is due to anodic corrosion of the SS spacer. Further study on two types of spacers, made by SS304 and SS316L, indicates that the SS316L spacer is more corrosion resistant, however, it still cannot support batteries for long-life cycling. The suitability for using LiFSI as a single electrolyte solute in Li-ion batteries can be guaranteed as long as, at the cathode, the charge voltage is strictly limited to the “threshold potential” and the SS components are avoided. This conclusion is further verified by using four different sources of LiFSI.

Multifunctional cationic molecular brushes-assisted fabrication of two-dimensional MoS2/carbon composites for ultrafast and long-term sodium storage

Molybdenum disulfide (MoS2) is considered as a promising anode for sodium-ion batteries (SIBs) because of its large interlayer space and high theoretical capacity. However, its practical application is seriously hampered by low electrical conductivity, sluggish reaction kinetics, and huge volumetric change. Herein, a class of two-dimensional (2D) sandwich-like carbon hybrids with MoS2-carbon nanoplates anchored on reduced graphene oxide (rGO) (rGO@MoS2–C) is successfully fabricated by homogeneously immobilizing abundant Mo anion on the surface of multifunctional cationic molecular brushes. The homogeneously dispersed MoS2 provides a large sodium-storage capacity, while the 2D rGO skeleton enables high electrical conductivity and rich surfaces/interfaces, and the amorphous carbon layers act as robust framework to address the volumetric expansion of MoS2. Benefiting from the elaborately integration of these merits, the rGO@MoS2–C with a MoS2 mass loading up to 87 wt% can realize excellent rate capability (348 mA h g−1 at 5 A g−1) as well as long-life cycling performance (305 mA h g−1 at 1 A g−1 after 2100 cycles), demonstrating great potential for practical application of SIBs.

Modern Supercapacitors Technologies and Their Applicability in Mature Electrical Engineering Applications

Supercapacitors can store a million times more energy per unit mass or volume compared to electrolytic capacitors. Due to their low internal resistance, they are capable of driving or absorbing pulsative high currents. Over the last quarter, century supercapacitor (SC) manufacturers have developed several families of mass-scale devices with high-power density and a longer cycle life that helped the end-users to improve their energy storage systems and products. Today, there are three common device families, namely, (i) symmetrical double-layer capacitors (EDLCs), (ii) hybrid capacitors with a lithium electrode, and (iii) battery capacitors based on pseudo capacitance concepts. This review paper compares these families and provides an overview of several state-of-the-art applications in electric vehicles (EVs), microgrids, and consumer electronics.

MOF-derived heterostructured C@VO2 @V2O5 for stable aqueous zinc-ion batteries cathode

Rationally designed cathode materials with high specific capacity and excellent cycling stability are indispensable for stable and highly efficient aqueous zinc-ion batteries (AZIBs). The mesoporous nanocomposite C@VO2 @V2O5 is successfully synthesized using the vanadium-based metal-organic framework as precursor by carbonization and subsequent oxidation processes. As the AZIBs cathode, the MOF-derived heterostructured materials display a high specific capacity (376 mAh g−1 at 0.05 A g−1), excellent rate capability (178 mAh g−1 at 5 A g−1) and outstanding long-life cycling (90.3% capacity retention for 2000 cycles at 5 A g−1). The promising electrochemical performance is attributed to abundant Zn2+ active sites and rapid intercalation kinetics of Zn2+ originated from the heterojunction structure at the two-phase (VO2 @V2O5) interface and mesoporous structure, and the enhanced electron transport efficiency brought by the the porous carbon skeleton with high conductivity. Furthermore, the synergistic effect of dual-ion co-intercalated energy storage mechanism endows C@VO2 @V2O5 with impressive electrochemical performance. This work demonstrates MOF-derived hetero-structured materials as an alternative cathode for high cyclic stability AZIBs in the future.

Application of Graphene Nanoplatelets in Supercapacitor Devices: A Review of Recent Developments.

As worldwide energy consumption continues to increase, so too does the demand for improved energy storage technologies. Supercapacitors are energy storage devices that are receiving considerable interest due to their appealing features such as high power densities and much longer cycle lives than batteries. As such, supercapacitors fill the gaps between conventional capacitors and batteries, which are characterised by high power density and high energy density, respectively. Carbon nanomaterials, such as graphene nanoplatelets, are being widely explored as supercapacitor electrode materials due to their high surface area, low toxicity, and ability to tune properties for the desired application. In this review, we first briefly introduce the theoretical background and basic working principles of supercapacitors and then discuss the effects of electrode material selection and structure of carbon nanomaterials on the performances of supercapacitors. Finally, we highlight the recent advances of graphene nanoplatelets and how chemical functionalisation can affect and improve their supercapacitor performance.

Carbon-Yarn-Based Supercapacitors with In Situ Regenerated Cellulose Hydrogel for Sustainable Wearable Electronics.

Developing sustainable options for energy storage in textiles is needed to power future wearable “Internet of Things” (IoT) electronics. This process must consider disruptive alternatives that address questions of sustainability, reuse, repair, or even a second life application. Herein, we pair stretch-broken carbon fiber yarns (SBCFYs), as current collectors, and an in situ regenerated cellulose-based ionic hydrogel (RCIH), as an electrolyte, to fabricate 1D fiber-shaped supercapacitors (FSCs). The areal specific capacitance reaches 433.02 μF·cm–2 at 5 μA·cm–2, while the specific energy density is 1.73 × 10–2 μWh·cm–2. The maximum achieved specific power density is 5.33 × 10–1 mW·cm–2 at 1 mA·cm–2. The 1D FSCs possess a long-life cycle and 92% capacitance retention after 10 000 consecutive voltammetry cycles, higher than similar ones using the reference PVA/H3PO4 gel electrolyte. Additionally, the feasibility and reproducibility of the produced devices were demonstrated by connecting three devices in series and parallel, showing a small variation of the current density in flat and bent positions. An environmentally responsible approach was implemented by recovering the active materials from the 1D FSCs and reusing or recycling them without compromising the electrochemical performance, thus ensuring a circular economy path.

(Digital Presentation) Ultra-Thick Electrodes Utilizing Short Diffusion Path Via Novel Micro-Casting Process for Lithium-Ion Batteries

For achieving high energy density, one effective way is to increase the active materials which makes thick electrodes for Lithium-ion Batteries (LIBs). However, thickening electrode limits the charge transport and generates significant mechanical stress that results in poor performance and eventually failure. In this work, a novel micro-casting (µ-casting) process has been introduced to fabricate ultra-thick and 3D structured electrodes which can address the issues with low charge transport by establishing short diffusion path (SDP). SDP reduces the intercalation-induced stress, improves energy density and long-term stability. The µ-casting allows ultra-thick (~280 µm) cathode (NMC 811, LiNi0.8Mn0.1Co0.1O2) and anode (MCMB, MesoCarbon MicroBeads) to achieve 40% higher specific capacity and 30% higher areal capacity after 200 cycles, high C-rate performance and longer cycle life with a intensive high mass loading of 35.7 mg/cm2.

Recent Advances Towards Practical LiNiO2 Cathode Materials: Optimised Calcination and Modification with W Via a Single Step Synthesis Route

LiNiO2 has been long considered as a promising cathode material owing to its high practical energy density [1,2]. However, structural and surface instabilities, coupled with complexities in the synthesis, have thus far prevented its commercialisation [3]. In this talk I will review our recent work towards the use of LiNiO2 as an actual cathode solution, via carefully controlled calcination conditions [4,5] and stabilization especially in terms of elemental substitution (doping) [6,7], but also of protective surface coating.To address issues with the material’s stability during synthesis and cycling, the use of an ammonium tungstate flux to modify both the LiNiO2 crystal structure and primary particle morphology without introducing additional steps into the synthesis will be discussed here in particular detail. The successful preparation of LiNiO2 modified with an industrially relevant amount of W (< 5 mol %) was confirmed using a combination of electron microscopy and synchrotron-based X-ray diffraction (XRD). Refinement of structural models against the data suggests tungsten dopant ions occupy the Ni site and concurrently induce migration of Ni2+ to the Li sites. Moreover, W enrichment at grain boundaries has been observed under some of the synthesis conditions. Variable temperature XRD was used to highlight the improved stability of the W-doped materials during the calcination at high temperatures. Electrochemical characterisation shows that W-doped LiNiO2 offers improved cycle life at the expense of little specific capacity. The structural consequences of tungsten doping on the behaviour of the material during electrochemical cycling was also investigated using operando XRD, showing reduced mechanical stress upon cycling. In conclusion, we will show that LiNiO2 modified by W with a simple route and no additional processing steps exhibits structural stability at high temperatures, offering a path towards the reliable synthesis of LiNiO2 with controlled morphology, improved chemomechanics and longer cycling life. Reference s : [1] Dahn et al., Structure and Electrochemistry of Li1+-yNiO2 and a New Li2NiO2 Phase with the Ni(OH)2 Structure, Solid State Ionics 1990, 44 (1-2), 87-97.[2] Rougier et al., Optimization of the composition of the Li1-zNi1+zO2 electrode materials: Structural, magnetic, and electrochemical studies, Journal of the Electrochemical Society 1996, 143 (4), 1168-1175[3] Bianchini et al., There and Back Again-The Journey of LiNiO2 as a Cathode Active Material. Angew. Chem., Int. Ed. 2019, 58, 10434−10458.[4] Kurzhals et al., The LiNiO2 Cathode Active Material: A Comprehensive Study of Calcination Conditions and their Correlation with Physicochemical Properties. Part I. Structural Chemistry, Journal of the electrochemical society, 2021, 168 (11) 110518.[5] Riewald et al., The LiNiO2 Cathode Active Material: A Comprehensive Study of Calcination Conditions and their Correlation with Physicochemical Properties. Part II. Morphology, Journal of the electrochemical society, 2022, 10.1149/1945-7111/ac4bf3[6] Goonetilleke et al., Single step synthesis of W-modified LiNiO2 using an ammonium tungstate flux, Journal of Materials Chemistry A 2022, 10.1039.D1TA10568J.[7] Weber et al., Tracing Low Amounts of Mg in the Doped Cathode Active Material LiNiO2, Journal of the electrochemical society, 2022, 10.1149/1945-7111/ac5b38.

Electrodeposition of Lithium Manganese Oxide Cathodes for Lithium-Ion Batteries

Lithium manganese oxides (LMOs) have drawn significant interest as cathode materials for lithium (Li)-ion batteries due to their high thermal stability, high energy density, and a longer cycle life at a lower cost than lithium cobalt oxides. A significant amount of research has been conducted to prepare cathode materials for Li-ion batteries ex-situ and then to integrate them into electrodes after forming a slurry with the binder and deposition onto the current collector. An alternative pathway to achieve active LMO cathodes is to directly synthesize them on the current collector via electrodeposition (ED). Using ED not only could improve active material utilization and electrode mechanical properties, but it may also reduce the cost of electrode fabrication as well as provide a pathway for facile recycling of spent manganese from a number of applications (e.g. alkaline batteries). To date, a few studies have reported the synthesis of LMOs by electrodeposition [1,2]. When doing this, the first step of the process is to deposit manganese oxide (s), MnxOy. Then, the oxide is lithiated to form the LMOs (i.e. LiMnxOy). Despite the fact that this process has been demonstrated, and active materials with reasonable capacity have been shown, it is presently unknown what LiMnxOy phase or phases are active. It is also not definitively known which MnxOy phase(s) is(are) involved in the transformation. To move the application of direct deposition of manganese oxide active phases closer to reality, a critical understanding of the solid-state chemistry for its conversion and energy storage is needed. In this study, Mn oxides were electrochemically prepared by potentiostatic deposition on multiple substrates and treated by lithium hydroxide. After that, the heat treatment of the lithiated deposits gave a mixture of LMOs as the cathode materials on the substrate. This talk will discuss the likely reactions for the formation of LMOs as well as their chemistry during charge/discharge. The morphology and the elemental composition of LMOs will be shown by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The composition and presence of crystalline Mn oxides and LMOs will be clarified by X-ray diffraction. Lastly, results will be shown regarding the cycle performance of the electrochemically prepared LMOs as well as the crystalline phases present after charge-discharge.

An Aqueous Binary Binder for Silicon-Based Electrodes

The relatively low coulombic efficiency (CE), especially the high initial capacity loss (ICL), and short cycle life are two major obstacles limit the wide adoption of Si-based materials as anodes of commercial lithium-ion batteries (LIBs). In this work, we introduced an aqueous binary binder composed of polyacrylic acid (PAA) and a water-soluble polymer to a Si-based electrode. Used as anodes of LIBs, the Si-based electrodes with the binary binder exhibited lower ICL and longer cycle life than those with PAA binder. The improved battery performance is ascribed to the unique electrode structure with the binary binder. The analysis from Fourier-transform infrared spectroscopy (FTIR) reveals that the intermolecular hydrogen bonds has been formed between PAA and the new polymer. The formation of hydrogen bonds could affect the properties of slurry for electrode coating and the structure of dried electrodes. Compared to the PAA binder, the new binary binder increases the viscosity of aqueous slurries at low shear rates and prompts the shear thinning, which benefit the preparation of slurries with high stability. Observations from the electron microscopy reveal that a relative porous structure was generated in the electrodes with the binary binder, compared with those with PAA binder. The porous structure could not only facilitate the electrolyte transport, but also accommodate the large volume expansion of Si during the charge/discharge processes. In addition, a thin solid-electrolyte-interface (SEI) film was found at the surface of cycled electrodes with the binary binder.Key words: aqueous binder coulombic efficiency Si-based anode lithium-ion battery