Recent Developments in the Effects of Different Dopants on the Structure and Property of Lithium Titanate Material

Xi-Yang Li,Qian-Lin Chen,Min Yang,Ya-Nan Li,Jing-Bo Ma 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

The lithium titanium spinel Li4Ti5O12 has attracted more and more attention as anode materials applied in lithium ion batteries. Li4Ti5O12 material has been found to be able to intercalate lithium ions without deformation of the lattice. However, compared with graphite and other anode materials, the low conductivity of Li4Ti5O12 restricts its charging and discharging rate. Doping is deemed to be a businesslike method to enhance ionic and electronic conductivity of Li4Ti5O12. This paper reviews the effects of Li4Ti5O12 with different doping ions on different crystal lattice states. And it has been found by a summary that the doping objective of doping ions at Li4Ti5O12 is also different. Moreover, the applications of ion doping in different fields of Li4Ti5O12 are prospected.

Designed seamless outer surface: Application for high voltage LiNi_0.5Mn_1.5O₄ cathode with excellent cycling stability

Zhang, Kan,Li, Ping,Ma, Ming,Park, Jong Hyeok Elsevier 2016 Journal of Power Sources Vol.336 No.-

<P><B>Abstract</B></P> <P>Suppressing side reactions at the cathode-electrolyte interface (CEI) is critical for alleviating capacity fading of the high-voltage (>5 V) spinel cathode material LiNi<SUB>0.5</SUB>Mn<SUB>1.5</SUB>O<SUB>4</SUB> (LNMO). The primary bottleneck in conventional nanoengineering of LNMO involves an antagonistic relationship between the positive effects of the nanometer particle size and negative effects stemming from the larger CEI area. Inspired by Buckminster Fuller's geodesic domes, we have designed a seamless LNMO hollow sphere (S-LNMO) that comprises average 120 nm-sized triangles and truncated triangle subunits by means of grain growth orientation. The “tensegrity” structure has efficiently hindered the interfacial side reaction, which occurs only within a depth of 5 nm from the surface, thereby improving its electrochemical stability. The embedded layered Li<SUB>2</SUB>TiO<SUB>3</SUB> (LTO) in bulk S-LNMO (LTO:S-LNMO) region further improved the high-rate performance, demonstrating an ∼110 mAh/g capacity with 80.9% retention after 400 cycles at 5 C and remaining stable after 900 cycles at 5 C even after being stored at 50 °C for one week.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Seamless disordered Fd3m-phase LiNi<SUB>0.5</SUB>Mn<SUB>1.5</SUB>O<SUB>4</SUB> hollow spheres are subtly designed. </LI> <LI> The seamless architecture minimized the interfacial side reaction. </LI> <LI> Nanometer depth analysis showed an electrolyte permeation distance of less than 5 nm. </LI> <LI> A layered Li<SUB>2</SUB>TiO<SUB>3</SUB> embedded in LiNi<SUB>0.5</SUB>Mn<SUB>1.5</SUB>O<SUB>4</SUB> enables high-rate performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Design and research of high misalignment tolerant magnetic couplers for dynamic wireless charging systems

Zhenjie Li,Xuezhi Yang,Jun Ma,Mingfei Ban,Yiqi Liu 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.3

This paper proposes a main-auxiliary cooperative receiving coil (MA-coil) with a lower space occupation rate and a simple control based on the time-sharing working principle, which can effectively improve the anti-misalignment capability of a dynamic wireless charging (DWC) system. First, the structure and circuit topology of the MA-coil are designed. The two auxiliary coils (A-coil) are connected in reverse series and symmetrically placed on both sides of the main coil (M-coil). Second, the output performance of the MA-coil in the y-direction is calculated based on the time-sharing working principle. The A-coil works by itself and enhances the output power when side shift occurs. Third, the most suitable ratio of coil width w M and w A is determined. The anti-misalignment performance and the effective side shift range are compared through simulation between the MA-coil in this case and the square coil. Finally, an experimental prototype is built to verify the feasibility of the proposed structure, and experimental results obtained from the prototype are basically consistent with the theoretical analysis. The anti-misalignment capability of the MA-coil is more than 20% higher than that of the square coil.

Sulphonated Reduced Graphene Oxide: A High Performance Anode Material for Lithium Ion Battery

Haibo Li,Rui Niu,Sen Liang,Yulong Ma,Min Luo,Jin Li,Lijun He 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4

In this work, the sulfonated reduced graphene oxide (SRGO) was synthesized and proposed as an enhanced anode material for lithium ion battery (LIB). The result shows that the SRGO has an improved battery performance (i.e., ~341.7 mAh/g and ~190.6 mAh/g corresponds to SRGO and RGO at the 100th cycle with a current density of 200 mA/g) and superior cycling stability compared with pristine reduced graphene oxide (RGO). These are attributed to the improved specific surface area (448.35 m2 /g) and conductivity (2.5 x 10-4 S/m). Further, the SRGO exhibits good rate capability and excellent energy density at various current densities ranging from 50 mAh/g to 2000 mAh/g, suggesting that SRGO could be a promising anode material for high capacity LIB.

Promising Carbon Matrix Derived from Willow Catkins for the Synthesis of SnO2/C Composites with Enhanced Electrical Performance for Li-Ion Batteries

Yong Li,Yun Zhao,Canliang Ma,Yongxiang Zhao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.08

Willow catkins as a kind of seasonal biomass are harmful to human health in terms of causing respiratory ailments and skin anaphylaxis every spring. To explore the high-value utilization of willow catkins, in this study, we attempt to develop a kind of tin-based anode materials with willow catkin derived carbon (WCC) as the matrix. A designed solvent-thermal method involving thiourea as stabilizer and acetone–H2O mixture as solvent has been employed to fabricate SnO2–WCC composites, which exhibit uniform deposition of well-dispersed SnO2 nanoparticles on the surface of WCC. As an anode material for lithium-ion batteries (LIBs), the SnO2–WCC composite delivered a stable discharge capacity of 565mAh g -1 at 100mA g -1 after 70 cycles and a good rate capability of 349mAh g -1 at 1000mA g -1. The high dispersity of SnO2 nanoparticles and high conductivity of WCC are both believed to contribute to the excellent electrochemical performances. These results suggest the potential of willow catkins derived carbonaceous materials applied in anode materials of LIBs and shed light on the creation of advanced carbon materials from other biomass materials towards energy storage applications.

Space-Time Quantization and Motion-Aligned Reconstruction for Block-Based Compressive Video Sensing

( Ran Li ),( Hongbing Liu ),( Wei He ),( Xingpo Ma ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.1

The Compressive Video Sensing (CVS) is a useful technology for wireless systems requiring simple encoders but handling more complex decoders, and its rate-distortion performance is highly affected by the quantization of measurements and reconstruction of video frame, which motivates us to presents the Space-Time Quantization (ST-Q) and Motion-Aligned Reconstruction (MA-R) in this paper to both improve the performance of CVS system. The ST-Q removes the space-time redundancy in the measurement vector to reduce the amount of bits required to encode the video frame, and it also guarantees a low quantization error due to the fact that the high frequency of small values close to zero in the predictive residuals limits the intensity of quantizing noise. The MA-R constructs the Multi-Hypothesis (MH) matrix by selecting the temporal neighbors along the motion trajectory of current to-be-reconstructed block to improve the accuracy of prediction, and besides it reduces the computational complexity of motion estimation by the extraction of static area and 3-D Recursive Search (3DRS). Extensive experiments validate that the significant improvements is achieved by ST-Q in the rate-distortion as compared with the existing quantization methods, and the MA-R improves both the objective and the subjective quality of the reconstructed video frame. Combined with ST-Q and MA-R, the CVS system obtains a significant rate-distortion performance gain when compared with the existing CS-based video codecs.

Sodium Alginate-Assisted Synthesis of PdAg Bimetallic Nanoparticles and their Enhanced Activity for Electrooxidation of Ethanol

Yanru Yin,Changna Wen,Ning Ma,Baoyan Wang,Lianying Zhang,Hongliang Li,Peizhi Guo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.9

Palladium and palladium-silver bimetallic nanocrystals have been synthesized hydrothermally by using environmental-friendly sodium alginate as the stabilizer and reducing agent. The pure palladium nanoparticles were spherical-like possibly due to the principle of the lowest surface energy, however, the formation of bimetallic palladium-silver nanoparticles was much more complicated, which was thinner and more irregular nanostructures than pure palladium nanoparticles. Electrochemical measurements showed that the electrocatalytic activity toward ethanol oxidation was increased first with the increase of silver content in bimetallic nanoparticles, from pure palladium of around 1070 mA/mg, to PdAg-20 of 1160 mA/mg and to PdAg-10 of 1750 mA/mg, and declined greatly at a high content of silver, approximately 279 mA/mg. Electrochemical stability test showed that PdAg-10 and PdAg-5 were the best and worst among four palladium-based samples, respectively. Based on the experimental data, the formation mechanism of pure palladium and palladium-silver bimetallic nanoparticles and the structure-property relationship of these samples have been discussed.

Estimating the State-of-Charge of Lithium-Ion Batteries Using an H-Infinity Observer with Consideration of the Hysteresis Characteristic

Xie, Jiale,Ma, Jiachen,Sun, Yude,Li, Zonglin The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

The conventional methods used to evaluate battery state-of-charge (SOC) cannot accommodate the chemistry nonlinearities, measurement inaccuracies and parameter perturbations involved in estimation systems. In this paper, an impedance-based equivalent circuit model has been constructed with respect to a LiFePO₄ battery by approximating the electrochemical impedance spectrum (EIS) with RC circuits. The efficiencies of approximating the EIS with RC networks in different series-parallel forms are first discussed. Additionally, the typical hysteresis characteristic is modeled through an empirical approach. Subsequently, a methodology incorporating an H-infinity observer designated for open-circuit voltage (OCV) observation and a hysteresis model developed for OCV-SOC mapping is proposed. Thereafter, evaluation experiments under FUDS and UDDS test cycles are undertaken with varying temperatures and different current-sense bias. Experimental comparisons, in comparison with the EKF based method, indicate that the proposed SOC estimator is more effective and robust. Moreover, test results on a group of Li-ion batteries, from different manufacturers and of different chemistries, show that the proposed method has high generalization capability for all the three types of Li-ion batteries.

Electrocatalytic oxygen reduction of three-dimensional carbon fiber-based composites for seawater oxygen-dissolved battery

Yu Juxin,Ma Li,Duan Tigang,Xin Yonglei,Lv Yanzhuo,Zhang Haibing 한국탄소학회 2022 Carbon Letters Vol.32 No.2

One-step hydrothermal reduction method was used to prepare three-dimensional carbon fiber brush-based graphene–platinum (CFB/Pt–G) composites to improve the electrocatalytic oxygen reduction activity of cathode materials for seawater oxygen-dissolved battery. Characterization results show that the reduced graphene oxide of as-prepared graphene–platinum composite displays the few-layer folded structure. In addition, Pt nanoparticles with the polycrystalline structure dispplay a preferential growth along the crystal plane of (111) and are mainly distributed around the defect cavities of folded graphene. Electrochemical results show that the diffusion-limited current density of CFB/Pt–G composite tested with 1600 rpm/min in 3.5% NaCl solution reaches 5 mA/cm2, while that of CFB/G is only 2.64 mA/cm2. Battery discharge results show that the maximum volume power density of CFB/Pt–G–Mg battery with a stable open voltage of 1.73 V is 81 times as much as the commercial seawater battery SWB1200.

Estimating the State-of-Charge of Lithium-Ion Batteries Using an H-Infinity Observer with Consideration of the Hysteresis Characteristic

Jiale Xie,Jiachen Ma,Yude Sun,Zonglin Li 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

The conventional methods used to evaluate battery state-of-charge (SOC) cannot accommodate the chemistry nonlinearities, measurement inaccuracies and parameter perturbations involved in estimation systems. In this paper, an impedance-based equivalent circuit model has been constructed with respect to a LiFePO₄ battery by approximating the electrochemical impedance spectrum (EIS) with RC circuits. The efficiencies of approximating the EIS with RC networks in different series-parallel forms are first discussed. Additionally, the typical hysteresis characteristic is modeled through an empirical approach. Subsequently, a methodology incorporating an H-infinity observer designated for open-circuit voltage (OCV) observation and a hysteresis model developed for OCV-SOC mapping is proposed. Thereafter, evaluation experiments under FUDS and UDDS test cycles are undertaken with varying temperatures and different current-sense bias. Experimental comparisons, in comparison with the EKF based method, indicate that the proposed SOC estimator is more effective and robust. Moreover, test results on a group of Li-ion batteries, from different manufacturers and of different chemistries, show that the proposed method has high generalization capability for all the three types of Li-ion batteries.