Structural and electrochemical evaluation of bismuth doped lithium titanium oxides for lithium ion batteries

Subburaj, T.,Prasanna, K.,Kim, Ki Jae,Ilango, P. Robert,Jo, Yong Nam,Lee, Chang Woo Elsevier 2015 Journal of Power Sources Vol.280 No.-

<P><B>Abstract</B></P> <P>Micro-sized Li<SUB>4</SUB>Ti<SUB>5−x</SUB>Bi<SUB>x</SUB>O<SUB>12</SUB> (0 ≤ x ≤ 0.15) materials are synthesized using a simple solid state method in air. The structural, morphological, and electrochemical characteristics of Bi-doped lithium titanates and pristine samples are methodically analyzed by X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The XRD and Raman spectroscopy results demonstrate that bismuth-doping do not alter the spinel structure and good crystalline materials are synthesized. The FE-SEM images show that all samples possess the same morphological characteristics, with a particle size distribution of 0.5–1 μm. The electrochemical cycling testing reveals that the Li<SUB>4</SUB>Ti<SUB>4.9</SUB>Bi<SUB>0.10</SUB>O<SUB>12</SUB> sample exhibits discharge capacities of 205.4 mAh g<SUP>−1</SUP>, 160.8 mAh g<SUP>−1</SUP>, and 135.4 mAh g<SUP>−1</SUP> after 50 cycles at 1C, 5C, and 10C-rates, respectively. The differential capacity curves suggest that the Li<SUB>4</SUB>Ti<SUB>4.9</SUB>Bi<SUB>0.10</SUB>O<SUB>12</SUB> sample has a weaker polarization effect than the other samples. The EIS measurements imply that the Li<SUB>4</SUB>Ti<SUB>4.9</SUB>Bi<SUB>0.10</SUB>O<SUB>12</SUB> sample possesses a high electronic conductivity and lithium ion diffusivity, which demonstrate that this new Li<SUB>4</SUB>Ti<SUB>4.9</SUB>Bi<SUB>0.10</SUB>O<SUB>12</SUB> material would be a good candidate as an anode for lithium ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bi-doped Li<SUB>4</SUB>Ti<SUB>5</SUB>O<SUB>12</SUB> anode materials are synthesized by facile solid-state method. </LI> <LI> Bi-doping leads to give high electronic conductivity and lithium diffusivity. </LI> <LI> Also, it is effective to be in stable structure and suppression of polarization effect. </LI> <LI> Li<SUB>4</SUB>Ti<SUB>4.9</SUB>Bi<SUB>0.10</SUB>O<SUB>12</SUB> material would be a good candidate as an anode for lithium ion batteries. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Investigation on high performance electrodes active materials for advanced lithium-ion rechargeable batteries

T. Subburaj 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.S1

High capacity layered Li[Lix(Ni0.3Co0.1Mn0.6)1-x]O2 (x = 0.11) cathode and high voltage Li4Ti5O12 spinel anode for the full cell systems have been studied. With combined this cathode and anode materials in an advanced lithium ion battery, a new electrochemical reaction has been demonstrated. It exhibited the initial discharge capacity of 173 mAhg-1 and also was maintained at the average specific capacity of 170 mAh/g and more than 90% capacity retention. In addition, the battery can cycle at C/10 up to 30 cycles with a very stable capacity delivery. Taking an average voltage of 2.5 V, a specific energy density value of 400 Wh/kg was obtained. These environmentally benign Mn-rich layered cathode and spinel Li4Ti5O12 anode materials are going to be future electrodes for Li-ion rechargeable batteries in hybrid electric vehicle applications.

Effect of monocationic ionic liquids as electrolyte additives on the electrochemical and thermal properties of Li-ion batteries

Subburaj, T.,Jo, Y.N.,Lee, C.W. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.8

The conventional electrolyte system has been compared with the ionic liquid (IL) additive containing electrolyte system at room temperature as well as elevated temperature. In this work, two types of monocationic ILs such as 1-butyl-3-methylpyrrolidinium hexafluorophosphate (Pyr IL) and 1-ethyl-3-methylimidazolium hexafluorophosphate (IMI IL) are added as an additive at two different weight ratios in 1.15 M LiPF<SUB>6</SUB> (EC/EMC = 3/7 v/v) electrolyte solution, the structural, electrochemical and thermal characteristics of LiNi<SUB>0.80</SUB>Co<SUB>0.15</SUB>Al<SUB>0.05</SUB>O<SUB>2</SUB> (NCA)/carbon full-cell in different electrolyte formulations have been reconnoitered. X-ray diffraction (XRD) studies have proved that IL as an electrolyte additive does not alter the structural stability of cathode materials after cycling. Under room temperature, Pyr IL additives at 1 wt% and 3 wt% deliver better cycleability than others, with the retention ratios of 93.62% and 92.8%, respectively. At elevated temperature, only 1 wt% Pyr IL additive is giving stable capacity retention ratio of 80.74%. Ionic conductivity and self-extinguishing time (SET) values are increasing with respect to the amount of additive added to the electrolyte. Thermal studies reveal that 3 wt% Pyr IL is favorable regarding the safety of the battery as it shows shifting of peak to higher temperature of 272.10 <SUP>o</SUP>C. Among the IL additives evaluated in this study, addition of 1 wt% Pyr IL is the most desirable additive for achieving the best cycling performance as well as thermal behavior of Li-ion batteries.

A Ripple Rejection Inherited RPWM for VSI Working with Fluctuating DC Link Voltage

T. Jarin,P. Subburaj,Shibu J V Bright 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.5

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal referencerandom carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

A Ripple Rejection Inherited RPWM for VSI Working with Fluctuating DC Link Voltage

Jarin, T.,Subburaj, P.,Bright, Shibu J V The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.5

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

Elucidation of cube-like red iron oxide @ carbon nanofiber composite as an anode material for high performance lithium-ion storage

P. Santhoshkumar,T. Subburaj,K. Karuppasamy,A. Kathalingam,Dhanasekaran Vikraman,박현창,김현석 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

Herein, a red iron oxide @ carbon fiber (RIO@CF) composite is prepared via a simple and effective singlehydrothermal and calcination process. The physico-chemical characteristics of as-prepared electrodeactive materials are examined by X-ray photoelectron spectroscopy, high resolution field emissionscanningelectron microscopy and field emission-tunneling electron microscopy analyses. When usedas the anode material in the Li-ion battery, as-prepared RIO@CF composite have shown a specific capacityof 1138 mAh g 1 after 150 cycles with a capacity retention of 86% at a current density of 100 mA g 1. Moreover, a specific capacity of 825 mAh g 1 is achieved in the first cycle at a current density of about5000 mA g 1. Thus, when compared to the pristine nano-cube-like red iron oxide (RIO) electrode material,the RIO@CF composite electrode exhibits an outstanding cyclic stability and rate capacity. This electrochemicalenhancement facilitates effective lithium ion transport into the RIO@CF composite electrode,thus improving the electrical conductivity. In addition, the application of a homogeneous carbon fibercoating can provide effective contact between the electrode surface and the electrolyte to further benefitthe electrochemical performance.

Physical and electrochemical performance of LiNi_1/3Co_1/3Mn_1/3O₂ cathodes coated by Sb₂O₃ using a sol–gel process

Ilango, P. Robert,Subburaj, T.,Prasanna, K.,Jo, Yong Nam,Lee, Chang Woo Elsevier 2015 Materials chemistry and physics Vol.158 No.-

<P><B>Abstract</B></P> <P>Sb<SUB>2</SUB>O<SUB>3</SUB>-coated LiNi<SUB>1/3</SUB>Co<SUB>1/3</SUB>Mn<SUB>1/3</SUB>O<SUB>2</SUB> cathode materials have been prepared using a sol–gel process. The surface-coated cathode materials have been physically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and field emission transmission electron microscopy (FE-TEM). The electrochemical characteristics have been investigated by electrochemical impedance spectroscopy (EIS), galvanostatic cycler, and cyclic voltammetry (CV). Moreover, the Sb<SUB>2</SUB>O<SUB>3</SUB> coating does not affect the crystal structure of LiNi<SUB>1/3</SUB>Co<SUB>1/3</SUB>Mn<SUB>1/3</SUB>O<SUB>2</SUB> but instead form a thin compact layer on the surface. The 1wt% of Sb<SUB>2</SUB>O<SUB>3</SUB>-coated LiNi<SUB>1/3</SUB>Co<SUB>1/3</SUB>Mn<SUB>1/3</SUB>O<SUB>2</SUB> cathode coated shows stable cyclability with capacity retention of 98% after the 30 cycles, which is higher than the bare and 2 wt% Sb<SUB>2</SUB>O<SUB>3</SUB>-coated cathodes and the EIS and CV tests illustrate the suppressed charge transfer resistance and good reversibility for the optimized coating concentration on the cathode.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We successfully prepared Sb<SUB>2</SUB>O<SUB>3</SUB>-coated LiNi<SUB>1/3</SUB>Co<SUB>1/3</SUB>Mn<SUB>1/3</SUB>O<SUB>2</SUB> cathodes by a sol–gel process. </LI> <LI> Sb<SUB>2</SUB>O<SUB>3</SUB> has been used as an additive to give a protection layer from HF attack. </LI> <LI> Electrochemical performance of 1 wt% Sb<SUB>2</SUB>O<SUB>3</SUB>-coated LiNi<SUB>1/3</SUB>Co<SUB>1/3</SUB>Mn<SUB>1/3</SUB>O<SUB>2</SUB> was superior. </LI> <LI> 1 wt% Sb<SUB>2</SUB>O<SUB>3</SUB>-coated LiNi<SUB>1/3</SUB>Co<SUB>1/3</SUB>Mn<SUB>1/3</SUB>O<SUB>2</SUB> cathodes reveal good cyclability at high rates. </LI> </UL> </P>

Influence of doping iron ions into Cu(In,Ga)Se2 films in the morphology and photovoltaic properties of thin-film solar cells

Guan-Lin Chiu,T. Subburaj,Sudipta Som,Chang-Ying Ou,Chung-Hsin Lu 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.10

The iron-ion doped Cu(In, Ga)Se2 thin films were prepared on flexible stainless steel substrates via a non-vacuum spin-coatingprocess. The influence of iron-ion doping in the morphology and properties of Cu(In, Ga)Se2 solar cells was investigated indetail. When the molar ratio of iron ions to the total amount of indium and gallium ions in Cu(In, Ga)Se2 was increased, thegrain sizes of the Cu(In, Ga)Se2 thin films were reduced and the grain morphology became angular. Iron-ion doping in Cu(In,Ga)Se2 thin films substantially facilitated the formation of grain boundaries and additional shunt paths, leading to highprobability of electron-hole recombination. As a result, the conversion efficiency of the prepared Cu(In, Ga)Se2 solar cellsdecreased dramatically due to iron-ion doping.