Novel Gel—like Process for Synthesizing Submicron LiaNi0.8Co0.2O2 Powders Used in Lithium Ion Batteries

A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders,using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity in the obtained precursor. The results of electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. Its initial capacity reached 181.6 mAh/g and reversible efficiency at the first cycle is about 88.6%.     

PVC DISULFIDE AS CATHODE MATERIALS FOR SECONDARY LITHIUM BATTERIES

PVC disulfide (2SPVC) was synthesized by solution crosslink and its molecular structure was confirmed by infrared spectrum. 2SPVC's specific area is 36.1 m2·g-1 tested by stand BET method, and granularity experiment gives out the particle size of d0.5= 11.3μm. With SEM (Scanning Electron Microscope) experiment the surface morphology and particle shape of 2SPVC were observed. Cyclic voltammetry (scan rate: 0.5 mV·s-1) shows that 2SPVC experience an obvious S-S redox reaction in charge-discharge process. When 2SPVC was used as cathode material for secondary lithium battery in a 1 mol·L-1 solution of lithium bis(trifluoromethylsulfonyl) imide (Li(CF3SO2)2N) in a 5:45:50 volume ratio mixture of o-xylene (oxy), diglyme (DG) and dimethoxymethane (DME) at 30℃, the first discharge capacity of 2SPVC is about 400.3 mAh·g-1 which is very close to its theoretical value (410.5 mAh·g-1) at a constant discharge current of 15 mA·g-1. It can retain at about 346.1 mAh·g-1 of discharge capacity after 30 charge-discharge cycles. So 2SPVC is a very promising cathode candidate for rechargeable lithium batteries.     

Molten salt synthesis (MSS) of Cu2Mo6S8—New way for large-scale production of Chevrel phases

The Chevrel phase (CP), Mo₆S₈, was found to be an excellent cathode material for rechargeable magnesium batteries. Mo₆S₈ is obtained by a leaching process of Cu₂Mo₆S₈, which removes the copper. A new method of Cu₂Mo₆S₈ production was developed. In contrast to the well-known solid-state synthesis of CP, the method is based on the reaction in a molten salt media (KCl). A fast kinetics of this reaction allows using less active, but more convenient precursors (sulfides instead of sulfur), decreasing temperature and synthesis duration, as well as operation in the inert atmosphere instead of dynamic evacuated systems. It was shown that the composition and the electrochemical behavior of the products obtained by MSS and by the solid-state synthesis are identical. Thus, the molten salt method is extremely attractive for the large-scale production of the active materials for Mg batteries.     

Impact Responses of Prismatic Lithium-Ion Battery Based on the Membrane Factor Method北大核心CSCD

Aimed at the internal short circuit problem due to large deformation of the prismatic lithium-ion battery cell under impact loadings, a simplified battery model was first established. Then the motion equations of velocity and displacement based on the membrane factor method were proposed. With the effects of the face-sheet thickness and the densification region on the normalized final deflection, impact response characteristics of prismatic battery cells were investigated in detail. The results show that, the improved motion equations involving the membrane factor can reflect the dynamic response mechanisms of the prismatic battery cell under impact loadings, and the large deflection under high-speed impact can be predicted. With the increase of the face-sheet thickness, the deflection of the battery cell’s lower part decreases obviously. However, the densification region expands with the face-sheet thickness. The deflection and the densification region of the cell’s lower part both increase with the inner core density of the battery. This proposed impact model provides a theoretical guidance for the multi-functional integrated dynamic design of prismatic battery cells. © 2022 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

碳包覆LiFePO4的一步固相法制备及高温电化学性能

Carbon coated LiFePO₄ cathode material was synthesized by one-step solid-state reaction and characterized by X-ray diffraction (XRD), field-emission-scanning electron microscope (FESEM). Electrochemical performances of the material as cathode in lithium-ion battery were investigated at medium and elevated temperature (30 and 55 ℃) by galvanostatic charge-discharge and A.C. impedance tests. The results show that carbon coated LiFePO₄ powder exhibits a well-crystallized olivine structure and spherical morphology with an average particle size of about 500 nm. Galvanostatic charge-discharge tests show that the reversible discharge capacity at 1 C and 1.5 C rates was improved from 121 and 105 mAh·g^-1 at 30 ℃ to 136 and 123 mAh·g^-1 at 55℃, respectively, while the enhancement of high temperature on electrochemical performance is less obvious at a rate lower than 0.5 C. Impedance spectra analyses indicate that the cathode material has a remarkably higher lithium-ion diffusivity at 55 ℃ than that at 30 ℃, which improves the electrochemical performance at high temperature.     

锂及锂离子蓄电池有机溶剂研究进展

从有机溶剂对电池安全性的影响，氧化稳定性，与负极的相容性及对电解液电导率的影响四个方面，论述了锂及锂离子蓄电池有机溶剂的化学和电化学，介绍了碳酸酯类，醚类和羧酸酯类溶剂的性质与电极的相容性及在有机电解液中的应用，对含硫，硼基及胺类有机溶剂等也作了论述。     

层状LiMnO2的固相合成及电化学性能

以Mn₂O₃和氢氧化锂为原料，通过焙烧合成出o-LiMnO₂。用X射线衍射和扫描电镜对不同温度下合成的粉末样品进行了表征，并研究了材料的电化学性能。通过对不同温度条件下烧结样品的晶胞参数、布拉格(110)晶面峰半高宽及电化学性能研究发现：600 ℃下合成样品的半高宽最大，堆垛层错率高，同时电化学性能也最好，首次放电容量达到156 mAh·g^-1，20次循环后仍保持在140 mAh·g^-1以上。中高温固相合成的o-LiMnO₂材料，在晶粒范围大小相近时，材料电化学性能与材料堆垛层错率相关。     

锂离子电池负极合金CoSn和Cu-Sn的制备与表征

CoSn alloy and Cu-Sn samples were synthesized by H₂-reduction following solid-state reaction between Co(Ⅱ)， Cu(Ⅱ)， Sn(Ⅳ) and NaOH at ambient temperature. The samples were characterized by XRD， SEM. The results showed that CoSn alloy (80～200nm) is globe-shaped， ultrafine hexagonal material， and Cu-Sn alloy powder consists of two phases， i.e. Cu₆Sn₅ and Cu₃Sn. Cu-Sn powder has spherical morphology and the particle size is estimated to be 60～70nm. The electrochemical performances of CoSn alloy and Cu-Sn powder were studied using lithium-ions model cell Li/LiPF₆ (EC+DMC)/CoSn (or Cu-Sn). It was demonstrated the reversible discharge capacities for 10 cycles keep above 280mAh·g^-1 for nanophase Cu-Sn， and 60mAh·g^-1 for CoSn alloy. Differ-ential capacity plots showed that the reaction mechanisms of Cu-Sn with lithium were reversible.     

Facile hydrothermal construction of Nb_2CT_x/Nb_2O_5 as a hybrid anode material for high-performance Li-ion batteries

Herein,a simple yet efficient hydrothermal strategy is developed to in-situ convert multi-layered niobium-based MXene(Nb_2 CT_x) to hierarchical Nb2 CTx/Nb_2O_5 composite.In the hybrid,the Nb_2O_5 nanorods are well dispersed in and/or on the Nb_2 CTx.Thanks to the synergetic contributions from the high capacity of Nb_2O_5 and superb electrical conductivity of the two-dimensional Nb_2 CT_x itself,the resultant Nb_2 CTx/Nb_2O_5 hybrid exhibits excellent rate behaviors and stable long-term cycling behaviors,when evaluated as anodes for Li-ion batteries.     

Electrolytic Co3O4 for thin-layer anodes of lithium-ion batteries

Electrolytic (e) cobalt oxide of a spinel structure, e-Co₃O₄, is obtained from the sulfate and nitrate (aqueous, water-alcohol) solutions containing Co²⁺ with the aim of using it in thin-layer anodes of lithium-ion batteries. The physicochemical and structural properties of the synthesized compounds are examined using thermal and x-ray diffraction analyses, absorption IR spectroscopy, and atomic force microscopy. The electrochemical characteristics of e-Co₃O₄ are determined in breadboards of lithium power sources and in the lithiumion system LiCoO₂/e-Co₃O₄.