A stable TiO2_{2}–graphene nanocomposite anode with high rate capability for lithium-ion batteries

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries. With the assistance of hydrazine hydrate as a reducing agent, graphene oxide was reduced while TiO$_{2}$ nanoparticles were grown in situ on the nanosheets to obtain the nanocomposite material. The morphology of the nanocomposite obtained consisted of TiO$_{2}$ particles with a size of ∼100 nm, uniformly distributed on the reduced graphene oxide nanosheets. The as-prepared TiO$_{2}$–graphene nanocomposite was able to deliver a capacity of 250 mA h g−1 ± 5% at 0.2C for more than 200 cycles with remarkably stable cycle life during the Li+ insertion/extraction process. In terms of high rate capability performance, the nanocomposite delivered discharge capacity of ca. 100 mA h g−1 with >99% coulombic efficiency at C-rates of up to 20C. The enhanced electrochemical performance of the material in terms of high rate capability and cycling stability indicates that the as-developed TiO$_{2}$–rGO nanocomposites are promising electrode materials for future Li-ion batteries

Overcoming the Interfacial Limitations Imposed by the Solid–Solid Interface in Solid‐State Batteries Using Ionic Liquid‐Based Interlayers

Li-garnets are promising inorganic ceramic solid electrolytes for lithium metal batteries, showing good electrochemical stability with Li anode. However, their brittle and stiff nature restricts their intimate contact with both the electrodes, hence presenting high interfacial resistance to the ionic mobility. To address this issue, a strategy employing ionic liquid electrolyte (ILE) thin interlayers at the electrodes/electrolyte interfaces is adopted, which helps overcome the barrier for ion transport. The chemically stable ILE improves the electrodes-solid electrolyte contact, significantly reducing the interfacial resistance at both the positive and negative electrodes interfaces. This results in the more homogeneous deposition of metallic lithium at the negative electrode, suppressing the dendrite growth across the solid electrolyte even at high current densities of 0.3 mA cm$^{-2}$. Further, the improved interface Li/electrolyte interface results in decreasing the overpotential of symmetric Li/Li cells from 1.35 to 0.35 V. The ILE modified Li/LLZO/LFP cells stacked either in monopolar or bipolar configurations show excellent electrochemical performance. In particular, the bipolar cell operates at a high voltage (≈8V) and delivers specific capacity as high as 145 mAh g$^{-1}$ with a coulombic efficiency greater than 99%

Recent advancements of n-doped graphene for rechargeable batteries: A review

Graphene, a 2D carbon structure, due to its unique materials characteristics for energy storage applications has grasped the considerable attention of scientists. The highlighted properties of this material with a mechanically robust and highly conductive nature have opened new opportunities for different energy storage systems such as Li-S (lithium-sulfur), Li-ion batteries, and metal-air batteries. It is necessary to understand the intrinsic properties of graphene materials to widen its large-scale applications in energy storage systems. In this review, different routes of graphene synthesis were investigated using chemical, thermal, plasma, and other methods along with their advantages and disadvantages. Apart from this, the applications of N-doped graphene in energy storage devices were discussed

말안장 구조를 가진 DRAM Cell 소자에서의 주변부 효과

Thesis(masters) --서울대학교 대학원 :전기. 컴퓨터공학부,2010.2.Maste

Graphene in Solid-State Batteries: An Overview

Solid-state batteries (SSBs) have emerged as a potential alternative to conventional Li-ion batteries (LIBs) since they are safer and offer higher energy density. Despite the hype, SSBs are yet to surpass their liquid counterparts in terms of electrochemical performance. This is mainly due to challenges at both the materials and cell integration levels. Various strategies have been devised to address the issue of SSBs. In this review, we have explored the role of graphene-based materials (GBM) in enhancing the electrochemical performance of SSBs. We have covered each individual component of an SSB (electrolyte, cathode, anode, and interface) and highlighted the approaches using GBMs to achieve stable and better performance. The recent literature shows that GBMs impart stability to SSBs by improving Li+ ion kinetics in the electrodes, electrolyte and at the interfaces. Furthermore, they improve the mechanical and thermal properties of the polymer and ceramic solid-state electrolytes (SSEs). Overall, the enhancements endowed by GBMs will address the challenges that are stunting the proliferation of SSBs

Interface in Solid-State Lithium Battery: Challenges, Progress, and Outlook

All-solid-state batteries (ASSBs) based on inorganic solid electrolytes promise improved safety, higher energy density, longer cycle life, and lower cost than conventional Li-ion batteries. However, their practical application is hampered by the high resistance arising at the solid-solid electrode-electrolyte interface. Although the exact mechanism of this interface resistance has not been fully understood, various chemical, electrochemical, and chemo-mechanical processes govern the charge transfer phenomenon at the interface. This paper reports the interfacial behavior of the lithium and the cathode in oxide and sulfide inorganic solid-electrolytes and how that affects the overall battery performance. An overview of the recent reports dealing with high resistance at the anodic and cathodic interfaces is presented and the scientific and engineering aspects of the approaches adopted to solve the issue are summarized.</p

Microstructure evolution and transport properties of garnet-type Li_6.5La_2.5Ba_0.5TaZrO₁₂ electrolyte for all-solid-state Li-ion batteries

The garnet-type Li6.5La2.5Ba0.5TaZrO12 (LLBTZO) electrolyte for Li-ion battery was synthesized by doping tantalum (Ta) and barium (Ba) in Li7La3Zr2O12 (LLZO) via solid-state method at different sintering temperatures (1100, 1150 and 1200 °C). The as-prepared sintered compositions were characterized for their physical properties using X-ray diffraction (XRD) which confirmed the formation of desired cubic phase of LLBTZO. The material was further investigated by using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and He-pycnometer to study morphological and electrochemical properties. Increasing the sintering temperature from 1100 to 1200 °C led to more than 60-fold increase in the ionic conductivity at 26 °C from 1.07 × 10−6 to 6.62 × 10−5 S/cm, which can be attributed to evolution of microstructures. With increasing sintering temperature, more of the powder surface is eliminated, the density of the resulting pellet was increased, and thus the total conductivity was enhanced.</p

Anodic WO₃ Mesosponge @ Carbon: A Novel Binder-less Electrode for Advanced Energy Storage Devices

A novel design for an anodic WO₃ mesosponge @ carbon has been introduced as a highly stable and long cyclic life Li-ion battery electrode. The nanocomposite was successfully synthesized via single-step electrochemical anodization and subsequent heat treatment in an acetylene and argon gas environment. Morphological and compositional characterization of the resultant materials revealed that the composite consisted of a three-dimensional interconnected network of WO₃ mesosponge layers conformally coated with a 5 nm thick carbon layer and grown directly on top of tungsten metal. The results demonstrated that the carbon-coated mesosponge WO₃ layers exhibit a capacity retention of 87% after completion of 100 charge/discharge cycles, which is significantly higher than the values of 25% for the crystalline (without carbon coating) or 40% for the as-prepared mesosponge WO₃ layers. The improved electrochemical response was attributed to the higher stability and enhanced electrical conductivity offered by the carbon coating layer

Coupling Particle Ordering and Spherulitic Growth for Long-Term Performance of Nanocellulose/Poly(ethylene oxide) Electrolytes

Development of lithium-ion batteries with composite solid polymer electrolytes (CPSEs) has attracted attention due to their higher energy density and improved safety compared to systems utilizing liquid electrolytes. While it is well known that the microstructure of CPSEs affects the ionic conductivity, thermal stability, and mechanical integrity/long-term stability, the bridge between the microscopic and macroscopic scales is still unclear. Herein, we present a systematic investigation of the distribution of TEMPO-oxidized cellulose nanofibrils (t-CNFs) in two different molecular weights of poly(ethylene oxide) (PEO) and its effect on Li+ ion mobility, bulk conductivity, and long-term stability. For the first time, we link local Li-ion mobility at the nanoscale level to the morphology of CPSEs defined by PEO spherulitic growth in the presence of t-CNF. In a low-MW PEO system, spherulites occupy a whole volume of the derived CPSE with t-CNF being incorporated in between lamellas, while their nuclei remain particle-free. In a high-MW PEO system, spherulites are scarce and their growth is arrested in a non-equilibrium cubic shape due to the strong t-CNF network surrounding them. Electrochemical strain microscopy and solid-state 7Li nuclear magnetic resonance spectroscopy confirm that t-CNF does not partake in Li+ ion transport regardless of its distribution within the polymer matrix. Free-standing CSPE films with low-MW PEO have higher conductivity but lack long-term stability due to the existence of uniformly distributed, particle-free, spherulite nuclei, which have very little resistance to Li dendrite growth. On the other hand, high-MW PEO has lower conductivity but demonstrates a highly stable Li cycling response for more than 1000 h at 0.2 mA/cm2 and 65 °C and more than 100 h at 85 °C. The study provides a direct link between the microscopic dynamic, Li-ion transport, bulk mechanical properties and long-term stability of the derived CPSE and, and as such, offers a pathway towards design of robust all-solid-state Li-metal batteries