Advanced Electrochemical Storage Research Articles

Bacterial assisted sustainable production of Three-Dimensional defective carbon from rice straw for supercapacitor

Defective carbon nanomaterials with three-dimensional (3D) structure are showing great potential for advanced electrochemical storage and conversion devices, but its application is restricted by the synthesis, which is usually involved with complicate and energy-intensive processes. Herein, pyrolysis of rice straw (RS) residue, of which is collected from the bacterial assisted hydrolysis, is proposed by us here, and the obtained bio-char is defective with 3D structure and rich in oxygen-containing functional groups. Compared to the pristine one, specific surface area of the representative RS carbon (RSC2) was increased from 428.8 to 1131.7 m2 g−1. The assembled supercapacitor with RSC2 showed a high specific capacitance of 331F g−1 at a charge–discharge current density of 0.5 A g−1, and a capacity retention of 97.6% was maintained at 5 A g−1 even after 10,000 cycles.

Nickel as a key element in the future energy

The review discusses the complex properties of nickel and its role as a critical element for ensuring a confident transition to a new technological paradigm from fossil fuels in favor of using advanced electrochemical storage and energy conversion systems. The main classes of nickel-containing materials of the positive electrode (cathode) for metal-ion batteries are discussed, the place of nickel among other 3<i>d</i>-metals used in the industry of electrochemical energy storage is determined. The main methods and approaches for the synthesis of state-of-the-art and next generation cathode materials based on layered Ni-containing oxides are presented. The crystal and electronic structures of these materials, including their evolution in the process of (de)intercalation of alkali metal cations, are considered in the context of their electrochemical properties. The most acute problems facing modern materials science on the way to commercialization and industrial production of new generation highenergy density cathode materials are determined. At the end of the review, promising directions for the further development of nickelcontaining cathode materials are outlined.<br> The bibliography includes 252 references.

Volume Changes of Graphite Anodes Revisited: A Combined Operando X-ray Diffraction and In Situ Pressure Analysis Study

Lithium intercalation into graphite is one of the electrochemically best studied solid-state reactions, and its application in lithium-ion batteries was a pioneering step in the development of advanced electrochemical storage devices. Therefore, one might expect that virtually any aspect of this important reaction has been examined both qualitatively and quantitatively. All the more, it is surprising that there are only a few experimental studies on the volume expansion of graphite, especially under cycling conditions. To the best of our knowledge, there exists no comprehensive set of structural data as a function of lithium content. Here, we present this missing information using combined results from electrochemical testing and operando X-ray diffraction. The changes in lattice parameters and unit cell volume are examined and related to the different intercalation stages and phase transition regimes. A total volume expansion (from space-group-independent evaluation) of 13.2% is observed when C6 is fully...

A fast and mild in-situ oxidization method to fabricate the nickel–cobalt layered double hydroxides on Ni foam as the high-performance electrode materials

In this work, a fast and mild in-situ oxidization hydrothermal method was developed to fabricate the nickel–cobalt layered double hydroxides (Ni–Co LDHs) on Ni foam. The Ni–Co LDHs with the nanoarrays and nanopetals structures were synthesized by in situ oxidizing Ni foam in a mixed solvent of cobalt chloride hexahydrate (CoCl[Formula: see text]H2O) and hydrogen peroxide (H2O2) at 90[Formula: see text]C for 3[Formula: see text]h. The electrochemical performance tests indicate the Ni–Co LDHs electrodes have a high areal capacitance value about 17.3[Formula: see text]F/cm2 at 5.0[Formula: see text]mA/cm2. After 1000 cycles at 50[Formula: see text]mA/cm2, the as-prepared electrodes have the high capacitance retention of 83%. Thus, the binder-free Ni–Co LDHs with high electrochemical performance are the promising electrode materials for advanced electrochemical storage energy devices including flexible power sources and supercapacitors in modern electronic systems.

Ethylene Glycol Intercalated Cobalt/Nickel Layered Double Hydroxide Nanosheet Assemblies with Ultrahigh Specific Capacitance: Structural Design and Green Synthesis for Advanced Electrochemical Storage.

Because of the rapid depletion of fossil fuels and severe environmental pollution, more advanced energy-storage systems need to possess dramatically improved performance and be produced on a large scale with high efficiency while maintaining low-enough costs to ensure the higher and wider requirements. A facile, energy-saving process was successfully adopted for the synthesis of ethylene glycol intercalated cobalt/nickel layered double hydroxide (EG-Co/Ni LDH) nanosheet assembly variants with higher interlayer distance and tunable transitional-metal composition. At an optimized starting Co/Ni ratio of 1, the nanosheet assemblies display a three-dimensional, spongelike network, affording a high specific surface area with advantageous mesopore structure in 2-5 nm containing large numbers of about 1.2 nm micropores for promoting electrochemical reaction. An unprecedented electrochemical performance was achieved, with a specific capacitance of 4160 F g(-1) at a discharge current density of 1 A g(-1) and of 1313 F g(-1) even at 50 A g(-1), as well as excellent cycling ability. The design and optimization of EG-Co/Ni LDH nanosheets in compositions, structures, and performances, in conjunction with the easy and relatively "green" synthetic process, will play a pivotal role in meeting the needs of large-scale manufacture and widespread application for advanced electrochemical storage.

Stable Lithium Electrodeposition in Liquid and Nanoporous Solid Electrolytes

High energy and safe electrochemical storage are critical components in multiple emerging fields of technology where portability is a requirement for performance and large-scale deployment. From advanced robotics, autonomous aircraft, to hybrid electric vehicles, the number of technologies demanding advanced electrochemical storage solutions is rising. The rechargeable lithium ion battery (LIB) has received considerable attention because of its high operating voltages, low internal resistance and minimal memory effects. Unfortunately LIBs are currently operating close to their theoretical performance limits due to the relatively low capacity of the anode LiC6 and the lithiated cathode materials (LiCoO2 and LiFePO4) in widespread use. It has long been understood that a rechargeable lithium metal battery (LMB), which eschewed the use of a carbon host at the anode can lead to as much as a ten-fold improvement in anode storage capacity (from 360 mAh g-1 to 3860 mAh g-1) and would open up opportunities for high energy un-lithiated cathode materials such as sulfur and oxygen, among others. Together, these advances would lead to rechargeable batteries with step-change improvements in storage capacity relative to today’s state of the art LIBs.A grand challenge in the field concerns the development of electrolytes, electrode, and battery systems configurations that prevent uneven electrodeposition of lithium and other metal anodes, and thereby eliminate dendrites at the nucleation step. It is understood that without significant breakthroughs in this area, the promise of LMBs, as well as of storage platforms based on more earth abundant metals such as Na and Al metal cannot be realized. Specifically, after repeated cycles of charge and discharge growing metal dendrites can bridge the inter-electrode space, producing internal short circuits in the cell. In a volatile electrolyte, ohmic heat generated by these shorts may lead to thermal runaway and catastrophic cell failure, which places obvious safety and performance limitations on the cells. The ohmic heat generated during a short-circuit may also locally melt dendrites to create regions of “orphaned” or electrically disconnected metal that results in a steady decrease in storage capacity as a battery is cycled. Lithium-ion batteries (LiB) are designed to remove these risks by hosting the lithium in a conductive carbon host at the anode. However, the small potential difference that separates lithium insertion into versus plating onto carbon can potentially lead to similar failure modes in an overcharged or too quickly charged LiB. Thus, the need for materials that prevent non-uniform electrodeposition of metals such as Li is also implicit in new fast charging LIB technology targeted for electric-drive vehicles. We have investigated electrodeposition of lithium in simple liquid electrolytes such as propylene carbonate, ethylene carbonate and diethyl carbonate, and in nanoporous solids infused with liquid electrolytes. We find that simple liquid electrolytes reinforced with LiXA blends exhibit stable long-term cycling at room temperature, often with no signs of deposition instabilities over hundreds of cycles of charge and discharge and thousands of operating hours. We rationalize these observations with the help of surface energy data for the electrolyte/lithium interface and impedance analysis of the interface during different stages of cell operation. Our findings provide support for an important recent theoretical prediction that the surface mobility of lithium is significantly enhanced in the presence of LiXA.

Design and Preparation of Materials for Advanced Electrochemical Storage

To meet the growing global demand for energy while preserving the environment, it is necessary to drastically reduce the world's dependence on non-renewable energy sources. At the core of this effort will be the ability to efficiently convert, store, transport and access energy in a variety of ways. Batteries for use in small consumer devices have saturated society; however, if they are ever to be useful in large-scale applications such as automotive transportation or grid-storage, they will require new materials with dramatically improved performance. Efforts must also focus on using Earth-abundant and nontoxic compounds so that whatever developments are made will not create new environmental problems. In this Account, we describe a general strategy for the design and development of new insertion electrode materials for Li(Na)-ion batteries that meet these requirements. We begin by reviewing the current state of the art of insertion electrodes and highlighting the intrinsic material properties of electrodes that must be re-engineered for extension to larger-scale applications. We then present a detailed discussion of the relevant criteria for the conceptual design and appropriate selection of new electrode chemical compositions. We describe how the open-circuit voltage of Li-ion batteries can be manipulated and optimized through structural and compositional tuning by exploiting differences in the electronegativity among possible electrode materials. We then discuss which modern synthetic techniques are most sustainable, allowing the creation of new materials via environmentally responsible reactions that minimize the use of energy and toxic solvents. Finally, we present a case study showing how we successfully employed these approaches to develop a large number of new, useful electrode materials within the recently discovered family of transition metal fluorosulfates. This family has attracted interest as a possible source of improved Li-ion batteries in larger scale applications and benefits from a relatively "green" synthesis.