Structure and electrochemical properties of multiple metal oxide nanoparticles as cathodes of lithium batteries

Abstract

Multiple metal oxide nanoparticles, which are the solid solutions of various kinds of divalent and trivalent metal ion oxides containing a certain amount of cation vacancy, with a uniform particle size less than 20 nm and huge surface area were synthesized by the calcination of layered double hydroxide (LDH) precursors, and their structures were analyzed using XRD and EXAFS. The electrochemical properties of these metal oxide nanoparticles as the cathode electrodes of Li batteries were also investigated by charge-discharge tests and AC-impedance measurements. Among the three kinds of multiple metal oxide nanoparticles prepared in this paper, Ni-V oxide showed the highest charge-discharge capacity of 327 mA h g À1 in the voltage range 4.2-1.0 V. According to the results of ex situ XRD, ex situ EXAFS and AC-impedance measurements, we have concluded that the discharge-charge process proceeds in the two stage reactions of (i) Li + intercalation-deintercalation to the cation vacancy and (ii) formation and decomposition of new surface phase reversibility without significant structural change.

XANES analysis for cation-vacancy distribution induced by doping Al ions in transition-metal-oxide anodes of lithium battery

“…One of the key factors is vacancies to compensate the excess charge of the higher valent vanadium ions and to keep the charge neutrality. They also confirmed Li + ions are inserted into cation vacancies in the Ni-V oxide by using XRD patterns and EXAFS analyses [3]. Moreover, Koo et al showed that a high concentration of cation vacancies in iron-oxide 25 nanoparticles leads a high capacity of about 132 mAhg −1 at a high voltage of 2.5 V without fading during more than 500 charge-discharge cycles [5].…”

“…All the chemicals used in this study were purchased from Kishida chemical (GR grade). A precursor of NiAllayer double hydroxides (LDHs) was synthesized by a coprecipitation method using Ni(NO 3 ) 2 •6H 2 O and Al(NO 3 ) 3 as starting materials [3]. An aqueous solution containing 1M NaOH and 0.1 M Na 2 CO 3 was added dropwise into the aqueous solution containing Ni:Al with a ratio of 2:1.…”

“…In particular, 3d transition metal oxide nanoparticles can reversibly react with lithium, so called conversion reaction (MO+2Li + +2e − Li 2 O + M) [1], to achieve higher capacities of 700 mAhg −1 [1] than that of the graphite one of 370 mAhg −1 which is currently used [2]. Although the nanoparticles also have good cycle performances as well as high reversible capacities, their capacity in the lower voltage region is very limited [3]. Hence, the improvement of the performance in the low voltage region is of great important.…”

A Large‐Sized Reduced Graphene Oxide with Low Charge‐Transfer Resistance as a High‐Performance Electrode for a Nonflammable High‐Temperature Stable Ionic‐Liquid‐Based Supercapacitor

“…[3] Typically,t he energy density of supercapacitors composed of porous activated carbon electrodes in aqueouselectrolyte is about 4-5 Wh kg À1 , [4] which is about one fifth that of lead acid batteries (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) Wh kg À1 ) and much lower than that of lithium ion batteries ( % 180 Wh kg À1 ). [7] Even though those organic electrolytesh ave ah ighero perating voltage than aqueous electrolytes, carefula nd expensive thermal controlsa re required for the necessary security requirementsc aused by the flammability and the high vapor pressure of the electrolytes. [7] Even though those organic electrolytesh ave ah ighero perating voltage than aqueous electrolytes, carefula nd expensive thermal controlsa re required for the necessary security requirementsc aused by the flammability and the high vapor pressure of the electrolytes.…”

“…[5,6] The carbon-based supercapacitors employ aprotics olvents as the electrolyte solutions,t ypicallya cetonitrile (ACN) or carbonate-based solvents such as propylene carbonate, ethylene carbonate. [7] Even though those organic electrolytesh ave ah ighero perating voltage than aqueous electrolytes, carefula nd expensive thermal controlsa re required for the necessary security requirementsc aused by the flammability and the high vapor pressure of the electrolytes. [8] Thus,i ti s essential to construct the suitable electrode materials and optimize the matched electrolytes to produce the efficient and secure supercapacitors with balanced powera nd energy densities.…”