One-pot synthesis of nitrogen-doped ordered mesoporous carbon spheres for high-rate and long-cycle life supercapacitors

Phase entropy as a function of lithium filling in the layered oxide S = KB ln(Ω) , Boltzman configuration entropy With Ω the configuration multiplicity (number of ways the inserted lithium cations could be arranged in the host lattice). Under the reasonable assumption of indistinguishable lithium cations, the configuration multiplicity of N lithium cations into the host material with Ns effective total number of sites follows the combinatorial equation below: Notes by MIT Student (and MZB)

Lithium Ion Batteries

Heteroatom Doping: An Effective Way to Boost Sodium Ion Storage

Hollow Carbon Spheres and Their Hybrid Nanomaterials in Electrochemical Energy Storage

Metal fluoride and oxides can store multiple lithium-ions through conversion chemistry to enable high energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage-profiles and the consequent low energy efficiency (< 80%). The physical origins of such hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM), density-functional-theory (DFT) calculations, and galvanostatic intermittent titration technique (GITT) to first correlate the voltage profile of iron fluoride ($FeF_3$), a representative conversion electrode material, with evolution and spatial distribution of intermediate phases in the electrode. The results reveal that, contrary to conventional belief, the phase evolution in the electrode is symmetrical during discharge and charge. However, the spatial evolution of the electrochemically active phases, which is controlled by reaction kinetics, is different. We further propose that the voltage hysteresis in the $FeF_3$ electrode is kinetic in nature. It is the result of Ohmic voltage drop, reaction overpotential, and different spatial distributions of electrochemically-active phases (i.e. compositional inhomogeneity). Therefore, the large hysteresis can be expected to be mitigated by rational design and optimization of material microstructure and electrode architecture to improve the energy efficiency of lithium-ion batteries based on conversion chemistry.

Origins of Large Voltage Hysteresis in High Energy-Density Metal Fluoride Lithium-Ion Battery Conversion Electrodes

Hollow porous carbon spheres with hierarchical nanoarchitecture for application of the high performance supercapacitors

Boron-doped ordered mesoporous carbons for the application of supercapacitors

The controllable morphology and size Li-rich Mn-based layered oxide Li1.2Ni0.13Co0.13Mn0.54O2 with micro/nano structure is successfully prepared through a simple coprecipitation route followed by subsequent annealing treatment process. By rationally regulating and controlling the volume ratio of ethylene glycol (EG) in hydroalcoholic solution, the morphology and size of the final products can be reasonably designed and tailored from rod-like to olive-like, and further evolved into shuttle-like with the assistance of surfactant. Further, the structures and electrochemical properties of the Li-rich layered oxide with various morphology and size are systematically investigated. The galvanostatic testing demonstrates that the electrochemical performances of lithium ion batteries (LIBs) are highly dependent on the morphology and size of Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials. In particular, the olive-like morphology cathode material with suitable size exhibits much better electrochemical performances comp...

Min Liu

Papers

Hollow porous carbon spheres with hierarchical nanoarchitecture for application of the high performance supercapacitors

Boron-doped ordered mesoporous carbons for the application of supercapacitors

Li1.2Ni0.13Co0.13Mn0.54O2 with Controllable Morphology and Size for High Performance Lithium-Ion Batteries

The effects of dual modification on structure and performance of P2-type layered oxide cathode for sodium-ion batteries

Cr-doped Fe2F5·H2O with open framework structure as a high performance cathode material of sodium-ion batteries