Ganguli Babu

Electrocatalytic Polysulfide Traps for Controlling Redox Shuttle Process of Li-S Batteries.

Stabilizing the polysulfide shuttle while ensuring high sulfur loading holds the key to realizing high theoretical energy of lithium-sulfur (Li-S) batteries. Herein, we present an electrocatalysis approach to demonstrate preferential adsorption of a soluble polysulfide species, formed during discharge process, toward the catalyst anchored sites of graphene and their efficient transformation to long-chain polysulfides in the subsequent redox process. Uniform dispersion of catalyst nanoparticles on graphene layers has shown a 40% enhancement in the specific capacity over pristine graphene and stability over 100 cycles with a Coulombic efficiency of 99.3% at a current rate of 0.2 C. Interaction between electrocatalyst and polysulfides has been evaluated by conducting X-ray photoelectron spectroscopy and electron microscopy studies at various electrochemical conditions.

Electrocatalysis of lithium polysulfides: current collectors as electrodes in li/s battery configuration

Lithium Sulfur (Li/S) chemistries are amongst the most promising next-generation battery technologies due to their high theoretical energy density. However, the detrimental effects of their intermediate byproducts, polysulfides (PS), have to be resolved to realize these theoretical performance limits. Confined approaches on using porous carbons to entrap PS have yielded limited success. In this study, we deviate from the prevalent approach by introducing catalysis concept in Li/S battery configuration. Engineered current collectors were found to be catalytically active towards PS, thereby eliminating the need for carbon matrix and their processing obligatory binders, additives and solvents. We reveal substantial enhancement in electrochemical performance and corroborate our findings using a detailed experimental parametric study involving variation of several kinetic parameters such as surface area, temperature, current rate and concentration of PS. The resultant novel battery configuration delivered a discharge capacity of 700 mAh g−1 with the two dimensional (2D) planar Ni current collectors and an enhancement in the capacity up to 900 mAh g−1 has been realized using the engineered three dimensional (3D) current collectors. The battery capacity has been tested for stability over 100 cycles of charge-discharge.

Power from nature: designing green battery materials from electroactive quinone derivatives and organic polymers

Current lithium ion battery technologies suffer from challenges derived from the eco-toxicity, costliness, and energetic inefficiency of contemporary inorganic materials used in these devices. Small organic molecules containing polycyclic aromatic moieties and polar functional groups have recently been presented as attractive electron donors that bind lithium and other small metal ions. This has endowed them with the potential to replace traditional inorganic electrodes consisting of metal composites. A family of naturally occurring carbonyl compounds, or quinones, have been of particular interest to the scientific community. However, they themselves have been plagued by issues of low voltages, poor conductivity, and capacity fading due to solubility in common polar electrolytes. Herein, we review a number of theoretical and experimental solutions to this problem, which include the use of heterocyclic derivatives, polymers, and conductive supramolecular carbon frameworks as electrochemical property enhancers, or stabilizers, of potential organic electrodes. This review focuses on the benign synthesis, current status, and future direction of organic battery materials with the aim of developing sustainable energy storage systems to meet the demands of a greener future.

Nanoflake driven Mn2O3 microcubes modified with cooked rice derived carbon for improved electrochemical behavior

Mn2O3 microcubes, symmetrically formed out of the systematic stacking of nanoflakes, built with nanoparticles in the 30–50 nm range have been obtained from a simple co-precipitation method. Excluding the requirement of a structure directing additive, the currently adopted synthesis protocol signifies the vital role of the rate of (NH4)HCO3 precursor addition, which has been optimized as 2 h for 300 mL to obtain uniformly stacked nanoflakes of Mn2O3 to form microcubes with desired morphological features. Cooked rice carbon (CRC), obtained from a filth-to-wealth conversion, has been used as conducting additive and an optimum concentration of 20 wt% CRC was found to be sufficient to form Mn2O3/CRC with improved lithium intercalation/de-intercalation behavior. The twin advantages, namely exploitation of a cheap and eco-benign composite additive obtained from a common domestic waste in the form of CRC and the optimized speed of addition of (NH4)HCO3 to form Mn2O3 microcubes obtained from nanoflakes offer advantages in terms of enhanced electronic conductivity and provision to buffer the volume changes of Mn2O3 anode, respectively. The optimized Mn2O3/CRC-20 composite anode exhibits an appreciable capacity of 830 mA h g−1 after formation cycle and an acceptable capacity of 490 mA h g−1 after completing 100 cycles, under the influence of 50 mA g−1 current density. Further, Mn2O3/CRC-20 anode exhibits a reasonable capacity of 450 mA h g−1 at 100 mA g−1 up to 50 cycles and qualifies itself as a potential anode material.

Quasi-Solid Electrolytes for High Temperature Lithium Ion Batteries.

Rechargeable batteries capable of operating at high temperatures have significant use in various targeted applications. Expanding the thermal stability of current lithium ion batteries requires replacing the electrolyte and separators with stable alternatives. Since solid-state electrolytes do not have a good electrode interface, we report here the development of a new class of quasi-solid-state electrolytes, which have the structural stability of a solid and the wettability of a liquid. Microflakes of clay particles drenched in a solution of lithiated room temperature ionic liquid forming a quasi-solid system has been demonstrated to have structural stability until 355 °C. With an ionic conductivity of ∼3.35 mS cm(-1), the composite electrolyte has been shown to deliver stable electrochemical performance at 120 °C, and a rechargeable lithium battery with Li4Ti5O12 electrode has been tested to deliver reliable capacity for over several cycles of charge-discharge.

Ionic Liquid–Organic Carbonate Electrolyte Blends To Stabilize Silicon Electrodes for Extending Lithium Ion Battery Operability to 100 °C

Fabrication of lithium-ion batteries that operate from room temperature to elevated temperatures entails development and subsequent identification of electrolytes and electrodes. Room temperature ionic liquids (RTILs) can address the thermal stability issues, but their poor ionic conductivity at room temperature and compatibility with traditional graphite anodes limit their practical application. To address these challenges, we evaluated novel high energy density three-dimensional nano-silicon electrodes paired with 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfonyl)imide (Pip) ionic liquid/propylene carbonate (PC)/LiTFSI electrolytes. We observed that addition of PC had no detrimental effects on the thermal stability and flammability of the reported electrolytes, while largely improving the transport properties at lower temperatures. Detailed investigation of the electrochemical properties of silicon half-cells as a function of PC content, temperature, and current rates reveal that capacity increases with PC content and temperature and decreases with increased current rates. For example, addition of 20% PC led to a drastic improvement in capacity as observed for the Si electrodes at 25 °C, with stability over 100 charge/discharge cycles. At 100 °C, the capacity further increases by 3-4 times to 0.52 mA h cm(-2) (2230 mA h g(-1)) with minimal loss during cycling.

Graphene-decorated graphite–sulfur composite as a high-tap-density electrode for Li–S batteries

Establishing the efficient electronic conductivity of a sulfur cathode without compromising the volumetric energy density and confining dissolved polysulfides within the cathode of the cell are first-order research priorities in the area of Li–S batteries. The emerging nanotechnology-based approaches, especially the use of porous nanocarbon in the formation of the sulfur electrode, stand to negatively affect the volumetric energy due to the low tap-density of C–S cathodes. In order to address these issues, we study the effects of the porosity and density of different carbons such as graphite, graphene and graphite–graphene hybrids on the overall volumetric capacity of the electrode. Although graphene–sulfur (GS) and graphene-decorated graphite–sulfur (GGS) electrodes show similar gravimetric capacities (~1050 mA h g−1), the GGS electrode exhibits a high volumetric capacity (745 mA h cm−3) without compromising the electrochemical stability over 50 cycles. Furthermore, an excellent cycle stability of the GGS electrode over 100 cycles is achieved by coating a thin layer of poly(methyl methacrylate) (PMMA) on the GGS electrode. Maintaining a high tap-density along with porosity is key in achieving high volumetric capacity in C–S cathodes.

Atomic Cobalt Covalently Engineered Interlayers for Superior Lithium‐Ion Storage

With the unique-layered structure, MXenes show potential as electrodes in energy-storage devices including lithium-ion (Li+ ) capacitors and batteries. However, the low Li+ -storage capacity hinders the application of MXenes in place of commercial carbon materials. Here, the vanadium carbide (V2 C) MXene with engineered interlayer spacing for desirable storage capacity is demonstrated. The interlayer distance of pristine V2 C MXene is controllably tuned to 0.735 nm resulting in improved Li-ion capacity of 686.7 mA h g-1 at 0.1 A g-1 , the best MXene-based Li+ -storage capacity reported so far. Further, cobalt ions are stably intercalated into the interlayer of V2 C MXene to form a new interlayer-expanded structure via strong V-O-Co bonding. The intercalated V2 C MXene electrodes not only exhibit superior capacity up to 1117.3 mA h g-1 at 0.1 A g-1 , but also deliver a significantly ultralong cycling stability over 15 000 cycles. These results clearly suggest that MXene materials with an engineered interlayer distance will be a rational route for realizing them as superstable and high-performance Li+ capacitor electrodes.

A common tattoo chemical for energy storage: henna plant-derived naphthoquinone dimer as a green and sustainable cathode material for Li-ion batteries

The burgeoning energy demands of an increasingly eco-conscious population have spurred the need for sustainable energy storage devices, and have called into question the viability of the popular lithium ion battery. A series of natural polyaromatic compounds have previously displayed the capability to bind lithium via polar oxygen-containing functional groups that act as redox centers in potential electrodes. Lawsone, a widely renowned dye molecule extracted from the henna leaf, can be dimerized to bislawsone to yield up to six carbonyl/hydroxyl groups for potential lithium coordination. The facile one-step dimerization and subsequent chemical lithiation of bislawsone minimizes synthetic steps and toxic reagents compared to existing systems. We therefore report lithiated bislawsone as a candidate to advance non-toxic and recyclable green battery materials. Bislawsone based electrodes displayed a specific capacity of up to 130 mA h g−1 at 20 mA g−1 currents, and voltage plateaus at 2.1–2.5 V, which are comparable to modern Li-ion battery cathodes.