Lithium difluoro(oxalate)borate‐based novel nanocomposite polymer electrolytes for lithium ion batteries

BACKROUND: HF formation and poor thermal stability found in commercial lithium ion batteries comprising LiPF₆ (and other salts) have hampered the replacement of LiPF₆. Therefore, a new kind of electrolyte salt is necessary to replace the one commercially available. RESULTS: A novel lithium difluoro(oxalate)borate (LiDFOB)‐based nanocomposite polymer electrolyte has been prepared in a matrix of poly[(vinylidene fluoride)‐co‐(hexafluoropropylene)] (PVdF‐HFP). The electrolyte contains ethylene carbonate and diethyl carbonate as plasticizers and nanoparticulate Sb₂O₃ as a filler. Membranes obtained by a solution casting technique were characterized by AC impedance, thermogravimetry and tensile strength measurements and morphological studies. Membranes with 5 wt% Sb₂O₃ exhibit a room‐temperature conductivity of 0.298 mS cm^?1, and are thermally stable up to ca 130 °C. Furthermore, the nanocomposite membranes show a 125% increase in mechanical stability as compared to filler‐free membranes. The structural change from α to β phases was confirmed by Raman studies. CONCLUSION: One of the important advantages of using LiDFOB lies in its bulkier DFOB anion, which also acts as solid plasticizer, thus improving the basic requirements of the electrolyte, such as mechanical and thermal stabilities, as well ionic conductivity and with a lower filler content. The overcharge tolerance of LiDFOB salt at higher temperature is also to be noted, because of the oxalate moieties. Preliminary investigations confirmed the possibility of using Sb₂O₃ nanoparticle‐filled membranes in industry in the near future. Copyright © 2008 Society of Chemical Industry     

P(VDF-HFP)/Al2O3基聚合物电解质薄膜的研究

采用溶液浇注和电解液吸收的方法制得了P（VDF-HFP)/Al2O3基聚合物凝胶电解质薄膜，用这种方法得到的共混薄膜具有较高的电解液吸收率及良好的机械性能，电化学阻抗谱的结果表明，与纳米粒径Al2O3共混得到的薄膜和镍电极具有较低的界面电阻，另外，由于该结构的半结晶性，DSC测试并没有发现该共混薄膜的玻璃化转变温度Tg。将此电解质隔膜组装成半电池后表现出优良的充放电性能。     

基于BC03蓝牙模组的无线有源音箱设计

给出了一种采用蓝牙模组的无线通信系统。将CSR的BC03蓝牙模组与TDA2030AOCL功放置于音箱中,通过C8051F020单片机UART0完成与蓝牙模组通信和控制,实现蓝牙手机或者PC电脑与BC03蓝牙模组的互连,完成HFP和A2DP功能,采用4×5键盘完成数据和音频控制指令的输入,并通过TS1602 LCD完成基本的数据和控制指令显示等。实验结果表明：本系统能够成功实现蓝牙手机或者PC设备与BC03蓝牙模组的互连,完成蓝牙模组的HFP和A2DP功能,音频最大输出功率可以达到14W（RL=4Ω）,可以直接驱动4Ω或者8Ω的音箱负载。     

Lewis acid–base property of P(VDF‐co‐HFP) measured by inverse gas chromatography

Poly (vinylidene fluoride‐co‐hexafluoropropylene) P(VDF‐co‐HFP) is an excellent material for polymer electrolytes of lithium ion battery. To enhance the lithium ion transference number, some metal oxides were often embedded into P(VDF‐co‐HFP). The promising mechanism for the increase in lithium ionic conductivity was Lewis acid‐base theory. In this experiment, the Lewis acid–base properties of P(VDF‐co‐HFP) were measured by inverse gas chromatography (IGC). The Lewis acid constant K_a of P(VDF‐co‐HFP) is 0.254, and the base constant K_b is 1.199. Compared with other polymers characterized by IGC, P(VDF‐co‐HFP) is the strongest Lewis basic polymers. Except aluminum ion, lithium ion is the strongest Lewis acidic ion according to their η value of Lewis acids. Therefore, a strong Lewis acid–base interaction will exist between lithium ion and P(VDF‐co‐HFP). This will restrict the transference of lithium ion in P(VDF‐co‐HFP). To enhance the lithium ion transference by blending other metal ions into P(VDF‐co‐HFP), it is suggested that the preferential ions should be Al³⁺, Mg²⁺, Na⁺, and Ca²⁺ because these metal ions have relative large η values. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

FTIR and DSC studies on gamma irradiated P(VdF-HFP) fluoropolymers applied to dosimetry

Radiation effects on semicrystalline poly(fluorovinylidene-co-hexafluoropropylene) copolymer [P(VdF-HFP)] induced by high-energy irradiation were investigated. Films with 150 μm thickness were irradiated with gamma doses ranging from 1.0 kGy to 3.0 MGy. Fourier transform infrared (FTIR) spectroscopy was used to follow the radio-induction of new molecular bonds. Differential scanning calorimetry (DSC) was employed to study the crystalline degradation of the irradiated samples. P(VdF-HFP) copolymers have fluorinated monomers [-CF₂-CF-CF₃-] randomly added to the [-CH₂-CF₂-] main chain of PVdF homopolymer. In this case, the [-CF₃-] molecular bonds are branched to the main chain. There is an increasing interest about the effect of high gamma radiation dose on the P(VdF-HFP) radiolysis, once it could enhance some of their already known interesting properties such as biomedical applications and electrostrictive transducers/actuators. FTIR spectroscopic data revealed two optical absorption bands at 1730 and 1754 cm⁻¹ whose intensities are unambiguously related to gamma delivered dose ranging from 0.0 to 1000 kGy. Fading analysis has demonstrated no loss of signal until 11 months after irradiation. DSC and XRD data revealed a continuous decrease in both the melting latent heat and crystalline dimensions for doses ranging from 250 to 3000 kGy. Because of the low fading and the linear behavior with respect to delivered gamma doses of the absorption band at 1754 cm⁻¹, P(VdF-HFP) copolymers are good candidates for being explored for high gamma dose dosimetry application.     

改性四氟乙烯—六氟丙烯共聚体的制造方法

针对四氟乙烯－六氟丙烯共聚过程，分析了低分子量改性剂使聚合物晶体中的自由基失活的机理，并通过实例阐述了低分子量改性剂对挤膜加工的改性作用。     

聚全氟乙丙烯聚合技术研究进展

综述了聚全氟乙丙烯制备技术中聚合介质改进、共聚反应控制方法研究、聚合物改性技术等方面的进展,并提出了值得关注的工程技术问题.     

Using high‐HFP‐content cathode binder for mitigation of heat generation of lithium‐ion battery

We investigate the effects of thermally sensitive binder (TSB) on the temperature increase of lithium‐ion battery (LIB) coin cell subjected to severe mechanical abuse. The TSB is poly(vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP), similar to conventional poly(vinylidenefluoride) (PVDF) binder but with a significant hexafluoropropylene (HFP) content. The testing data show that by using TSB, the peak temperature increase of nail‐penetrated LIB coin cell can be reduced by 20% to 40%, attributed to the softening of TSB that begins from ~80°C. The cycling performance of the LIB cells is also characterized. This research sheds light on the development of thermal‐runaway mitigation techniques.     

Flexible carbon nanotube--Cu2O hybrid electrodes for li-ion batteries

This study demonstrates the formation of a flexible and free-standing carbon nanotube-copper oxide-poly(vinylidene fluoride) (CNT-Cu(2) O-PVDF) nanocomposite and its application as an electrode-separator material for Li-ion batteries. Binder-free hybrid electrodes are obtained by conformally coating CNTs with Cu(2) O via electrodeposition and then embedding the resulting architecture into a porous poly(vinylidene fluoride-hexafluoropropylene) PVDF-HFP-SiO(2) polymer electrolyte membrane. The synergistic presence of high-capacity transition metal oxides and conductive CNTs results in twice the reversible areal capacity of 2.3 mAh cm(-2) as compared to 1.2 mAh cm(-2) for pure CNTs.     

车载蓝牙免提系统研究

通过对蓝牙技术的介绍,分析了蓝牙免提协议(HFP)的结构,结合实际项目介绍了蓝牙在车载免提系统中的应用,并且给出了该系统实现的详细方案,包括硬件结构,软件流程.最后对蓝牙技术在嵌入式系统中应用的前景进行了展望.