脉冲激光沉积NiCo2S4薄膜及其电化学特征

采用脉冲激光沉积法制备了NiCo₂S₄薄膜,利用恒流充放电和循环伏安测试研究了NiCo₂S₄薄膜作为锂离子电池负极材料的电化学性能和充放电机理。采用高分辨电子显微镜和选区电子衍射(TEM&SAED)表征了NiCo₂S₄薄膜首次循环过程中的组成与结构变化。恒流充放电测试结果显示NiCo₂S₄薄膜在3 μA·cm^-2的放电电流下,0~3 V(vs Li⁺/Li)范围内,薄膜的首次放电容量为698 mAh·g^-1,经过200次循环之后的放电容量为365 mAh·g^-1;在循环伏安测试中得到了分步反应的可逆氧化还原峰。TEM和SAED分析结果揭示了NiCo₂S₄薄膜与Li的电化学反应机理：首次放电过程中NiCo₂S₄与Li发生转化反应生成了Li₂S、Ni和Co,充电后生成了CoS和NiS复合薄膜。后续循环为CoS和NiS复合薄膜的可逆分解与形成。研究表明NiCo₂S₄是一种有潜在应用价值的锂离子电池负极材料。     

脉冲激光沉积NiCo2S4薄膜及其电化学特征研究

采用脉冲激光沉积法制备了NiCo₂S₄薄膜,利用恒流充放电和循环伏安测试研究了NiCo₂S₄薄膜作为锂离子电池负极材料的电化学性能和充放电机理。采用高分辨电子显微镜和选区电子衍射(TEM&SAED)表征了NiCo₂S₄薄膜首次循环过程中的组成与结构变化。恒流充放电测试结果显示NiCo₂S₄薄膜在3 μA·cm^-2的放电电流下,0~3 V(vs Li⁺/Li)范围内,薄膜的首次放电容量为698 mAh·g^-1,经过200次循环之后的放电容量为365 mAh·g^-1;在循环伏安测试中得到了分步反应的可逆氧化还原峰。TEM和SAED分析结果揭示了NiCo₂S₄薄膜与Li的电化学反应机理：首次放电过程中NiCo₂S₄与Li发生转化反应生成了Li₂S、Ni和Co,充电后生成了CoS和NiS复合薄膜。后续循环为CoS和NiS复合薄膜的可逆分解与形成。研究表明NiCo₂S₄是一种有潜在应用价值的锂离子电池负极材料。     

Li3V2(PO4)3电极过程及其锂离子脱嵌动力学研究(I)

采用溶胶凝胶法合成了Nasicon化合物Li₃V₂(PO₄)₃, 采用X射线衍射(XRD)对产品进行了物相分析. 采用充放电测试, 循环伏安(CV)研究了化合物的电化学性能和锂离子的脱嵌过程, 计算出Li^＋在固相中的扩散系数(10^－8 cm²•s^－1); 采用交流阻抗测试(EIS)研究了Li₃V₂(PO₄)₃的电极过程; 对两种类型的阻抗图谱提出不同等效电路模型并对结果进行了拟合; 研究了Li₃V₂(PO₄)₃电极过程动力学以及新鲜电极界面在充放电过程中的变化特性.     

Li3V2(PO4)3电极过程及其锂离子脱嵌动力学研究(I)

采用溶胶凝胶法合成了Nasicon化合物Li₃V₂(PO₄)₃, 采用X射线衍射(XRD)对产品进行了物相分析. 采用充放电测试, 循环伏安(CV)研究了化合物的电化学性能和锂离子的脱嵌过程, 计算出Li^＋在固相中的扩散系数(10^－8 cm²•s^－1); 采用交流阻抗测试(EIS)研究了Li₃V₂(PO₄)₃的电极过程; 对两种类型的阻抗图谱提出不同等效电路模型并对结果进行了拟合; 研究了Li₃V₂(PO₄)₃电极过程动力学以及新鲜电极界面在充放电过程中的变化特性.     

Mn4N薄膜与锂的电化学反应性能

采用脉冲激光沉积辅助高压电离的方法在不锈钢基片上制备了Mn₄N薄膜. 用充放电和循环伏安测试对该薄膜电极的电化学性能进行了表征. 该薄膜电极的首次放电容量为420 mAh•g^-1, 第一次充放电不可逆容量约为50%. 采用XRD, XPS, SEM对薄膜的化学组成和表面形貌进行了表征, 并对反应机理进行了研究, 结果表明Mn4N在反应过程中转化为金属Mn和Li₃N, 只有部分的Mn与Li₃N参与了可逆的电化学反应.     

Li4Ti5O12/CMK-3复合材料的制备及其作为锂离子电池负极材料的性能

将LiNO₃和Ti(OC₄H₉)₄填填充在有序介孔碳CMK-3 孔道中, 然后烧结合成了Li₄Ti₅O₁₂/CMK-3复合材料. 利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)对其结构和微观形貌进行了表征. 利用差热-热重分析(TG-DTA)测试复合材料中Li₄Ti₅O₁₂的含量. 利用充放电测试、循环伏安和电化学阻抗技术考察了复合材料作为锂离子电池负极材料的性能. 发现Li₄Ti₅O₁₂分布在CMK-3孔道中及其周围, 复合材料的高倍率充放电性能显著优于商品Li₄Ti₅O₁₂, 复合材料中Li₄Ti₅O₁₂的比容量明显高于除去CMK-3的样品(在1C倍率时比容量为117.8 mAh·g^-1), 其0.5C、1C和5C倍率的放电比容量分别为160、143 和131 mAh·g^-1, 库仑效率接近100%, 5C倍率时循环100次的容量损失率只有0.62%. 本研究结果表明CMK-3明显提高了Li₄Ti₅O₁₂的高倍率充放电性能, 可能是CMK-3特殊的孔道结构和良好的导电性减小了Li₄Ti₅O₁₂的粒径并提高了其电导率.     

脉冲激光沉积GeO2薄膜的电化学性能

采用脉冲激光沉积法在不锈钢基片上制备了GeO₂薄膜。充放电性能显示其具有高达1 336 mAh·g^-1可逆容量，这相当于每个GeO₂可与5.1个Li发生反应。其循环伏安特性显示在1.2 V和0.4 V处出现一对新的氧化还原峰。充放电后薄膜的组成与结构通过非原位高分辨电子显微和选区电子衍射来表征。结果显示在外电场作用下，Ge能够可逆地驱动Li₂O分解和形成。这是金属氧化物的一种新的电化学反应机理。     

三维尖晶石Li4Ti5O12纳米丝网状电极的构置与电化学性能

首次采用电纺丝技术结合高温退火成功地构置了含尖晶石Li₄Ti₅O₁₂的纳米纤维丝三维(3D)网状结构，并测量了三维电池的充放电性能。X射线衍射谱(XRD)、扫描电子显微镜(SEM)和电池循环性能测试等方法表征纤维丝3D结构和电化学性能。研究结果表明了Li₄Ti₅O₁₂纳米丝的零应变特性、构建的3D阵列的结构稳定性和在大电流密度下较好的充放电性能。显示了Li₄Ti₅O₁₂可作为3D电池的电极材料。     

锂离子电池正极材料Li1.2Mn0.54-xNi0.13Co0.13ZrxO2的制备及电化学性能

为了改善富锂锰基正极材料Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ 的循环性能,采用燃烧法合成了正极材料Li_1.2Mn_0.54-xNi_0.13Co_0.13Zr_xO₂（x=0.00,0.01,0.02,0.03,0.06）. 通过X射线衍射（XRD）和扫描电镜（SEM）对其结构与形貌进行了表征,利用恒电流充放电测试,循环伏安（CV）及电化学交流阻抗谱（EIS）技术对其电化学性能进行测试. 结果表明,Li_1.2Mn_0.54-xNi_0.13Co_0.13Zr_xO₂（x=0.00,0.01,0.02,0.03,0.06）正极材料均具有α-NaFeO₂型层状结构;在室温,2.0-4.8 V电压范围,以0.1C和1.0C（充放电电流以1.0C=180 mA·g^-1计算）倍率充放电进行测试,样品Li_1.2Mn_0.52Ni_0.13Co_0.13Zr_0.02O₂的首次放电比容量分别为280.3 和206.4 mAh·g^-1. 其中,在1.0C倍率下,100次循环后容量保持率由原来的73.2%提高到88.9%;以5.0C倍率充放电进行测试,经50次循环后,掺杂正极材料的放电比容量为76.5 mAh·g^-1,而未掺杂材料仅有15.0 mAh·g^-1. 在50、25 和-10 ℃,2.0C倍率条件下,掺杂正极材料的电化学性能均得到有效改善,其中,在- 10℃ 经过50 次循环后正极材料Li_1.2Mn_0.52Ni_0.13Co_0.13Zr_0.02O₂比未掺杂的正极材料相比,其放电比容量提高了61.1%.     

一种新型物理交联型凝胶聚合物电解质的制备与表征

以甲氧基聚乙二醇甲基丙烯酸酯(MPEGM)和十六烷基聚乙二醇甲基丙烯酸酯(HPEGM)为单体, 三乙二醇二甲醚(TEGDME)为增塑剂, 与锂盐(高氯酸锂, LiClO₄)和光引发剂(安息香二甲醚, DMPA)复合制成光敏体系, 经紫外(UV)固化得到物理交联型凝胶聚合物电解质(GPE)薄膜. 用红外(IR)光谱、差热分析(DSC)、拉伸测试和交流阻抗(AC) 等方法对聚合物基体和电解质的性能进行了研究.结果表明: 当共聚物P(MPEGM-co-HPEGM)中HPEGM含量为50%(w)时, 十六烷基链段(C₁₆)在聚氧化乙烯(PEO)链段静电斥力的作用下发生聚集, 自组装形成了物理交联, 提高了共聚物的空间稳定性; 温度和电解质中各组分的含量对电导率均有较大的影响, 综合性能较好的电解质在30℃时电导率可达0.87×10^-3 S·cm^-1; 采用循环伏安法测得该电解质的电化学窗口为0~4.5 V (vs. Li/Li⁺), 可以满足锂离子电池的应用要求; 组装成的LiFePO₄/GPE/Li电池, 在30℃下以0.1 C和0.2 C倍率进行充放电测试, 首次放电容量分别为154.7和148.0 mAh·g^-1.     

A novel anode material of antimony nitride for rechargeable lithium batteries

Antimony nitride thin film has been successfully fabricated by magnetron sputtering method and its electrochemistry with lithium was investigated for the first time. The reversible discharge capacity of Sb₃N/Li cells cycled between 0.3 V and 3.0 V was found above 600 mAh/g. By using transmission electron microscopy and selected area electron diffraction measurements, the conversion reaction of Sb₃N into Li₃Sb and Li₃N was revealed during the lithium electrochemical reaction of Sb₃N thin film electrode. The high reversible capacity and the good cycleability made Sb₃N one of promising anode materials for future rechargeable lithium batteries.     

脉冲激光沉积法制备FeSe薄膜电极及其电化学性质

采用脉冲激光溅射Fe和Se粉末的混合靶制备FeSe薄膜并用XRD、充放电和循环伏安测试研究了薄膜的结构和电化学性质. XRD结果显示, 当基片温度为200 ℃时, 薄膜主要由晶态的FeSe组成. 在电压1.0～3.0 V范围内, 该薄膜的可逆容量为360.8 mAh•g^－1, 经过100次循环之后的放电容量为396.5 mAh•g^－1, 具有很好的循环性能. ex situ XRD结果显示FeSe能够和Li发生可逆的电化学反应, 颗粒尺寸大于5 nm的纳米铁颗粒能够驱动Li₂Se的分解并在充电过程中重新生成FeSe. FeSe具有较高的可逆容量和较好的循环性能, 可能成为一种优良的锂二次电池正极材料.     

Thin film nonstoichiometric chromium oxide-based cathode material for rechargeable and primary lithium batteries

The application of nonstoichiometric chromium oxide-based thin film cathodes in lithium rechargeable and primary batteries operating at high rates has been demonstrated. Films of varying composition have been obtained by anionic Cr (VI) species electrodeposition on a 1X18N10Т grade stainless steel cathode from fluoride-containing electrolytes. The effect of film doping by Li⁺ ions during its electrosynthesis has been сonsidered. As-prepared films were studied by scanning and transmission electron microscopies, 3D optical profiler, thermogravimetric analysis, chemical analysis, and X-ray diffraction (XRD). The main phase components of the electrodeposited films regardless of Li⁺ in an electrolyte are Cr₂O₃, α-CrOOH, β-CrOOH, and metallic chromium as shown by XRD pattern refinement. The electrochemical reduction rate in a non-aqueous electrolyte (1 M LiClO₄ in PC/DME) correlates with the chromium oxide-hydroxide component content of film. Primary CrO _x -Li CR2325 mock-up cathode coating can be discharged in a pulsed mode at 10 Ω external resistance with 80–84 mA cm^?2 current densities for 10–100 ms. Thin film cathodes electrodeposited in the presence of lithium ions become rechargeable when the lithium content of the film reaches 0.02 wt.%. Mock-ups of CR2325 coin battery with a thin film cathode doped with lithium ions can be discharged more than 40 times with 136 mAh g^?1 specific capacity, 461 Wh kg^?1 specific energy and 154 W kg^?1 power density at 30 kΩ external resistance. The simplicity of thin film preparation makes this technology promising for thin film lithium batteries.     

Lithium electrochemistry of NiSe2: A new kind of storage energy material

NiSe₂ thin film has been successfully fabricated by reactive pulsed laser deposition and was investigated for its electrochemistry with lithium for the first time. The reversible discharge capacities of NiSe₂/Li cells cycled between 1.0 V and 3.0 V were found in the range of 314.9–467.5 mA h g⁻¹ during the first 200 cycles. By using ex situ X-ray diffraction, transmission electron microscopy, and selected-area electron diffraction measurements, the intermediates of β-NiSe, and Ni₃Se₂ were identified during the reversible conversions of NiSe₂ into metal nickel and Li₂Se. Both cation (nickel) and anion (selenium) in NiSe₂ provide the redox active centers in its electrochemical reaction with lithium, indicating one of the features of its lithium electrochemistry. The high reversible capacity and good cycle ability of NiSe₂ electrode made it become a promising cathode material for future rechargeable lithium batteries.     

Cu3V2O8 Nanoparticles as Intercalation‐Type Anode Material for Lithium‐Ion Batteries

Cu₃V₂O₈ nanoparticles with particle sizes of 40–50 nm have been prepared by the co‐precipitation method. The Cu₃V₂O₈ electrode delivers a discharge capacity of 462 mA h g^?1 for the first 10 cycles and then the specific capacity, surprisingly, increases to 773 mA h g^?1 after 50 cycles, possibly as a result of extra lithium interfacial storage through the reversible formation/decomposition of a solid electrolyte interface (SEI) film. In addition, the electrode shows good rate capability with discharge capacities of 218 mA h g^?1 under current densities of 1000 mA g^?1. Moreover, the lithium storage mechanism for Cu₃V₂O₈ nanoparticles is explained on the basis of ex situ X‐ray diffraction data and high‐resolution transmission electron microscopy analyses at different charge/discharge depths. It was evidenced that Cu₃V₂O₈ decomposes into copper metal and Li₃VO₄ on being initially discharged to 0.01 V, and the Li₃VO₄ is then likely to act as the host for lithium ions in subsequent cycles by means of the intercalation mechanism. Such an “in situ” compositing phenomenon during the electrochemical processes is novel and provides a very useful insight into the design of new anode materials for application in lithium‐ion batteries.     

InP as new anode material for lithium ion batteries

InP thin film has been successfully fabricated by pulsed laser deposition (PLD) and was investigated for its electrochemistry with lithium for the first time. InP thin film presented a large reversible discharge capacity around 620 mAh g^?1. The reversibility of the crystalline structure and electrochemical reaction of InP with lithium were revealed by using ex situ XRD and XPS measurements. The high reversible capacity and stable cycle of InP thin film electrode with low overpotential made it one of the promise energy storage materials for future rechargeable lithium batteries.     

Electrochemical reactions of lithium with CuP2 and Li1.75Cu1.25P2 synthesized by ballmilling

Copper phosphide (CuP₂) and lithium copper phosphide (Li_1.75-Cu_1.25P₂) were synthesized by high-energy ballmilling at room temperature. The electrochemical reactions between lithium and these samples have been studied. The first lithium insertion into the CuP₂ phase till 0.0 V vs. Li leads to copper reduction and the formation of lithium phosphide (Li₃P), corresponding to a long voltage plateau. The subsequent lithium extraction until 1.3 V vs. Li presents three voltage plateaus related to the formation of new phases such as Li₂CuP, giving a reversible capacity about 810 mAh/g and faradic yield about 61%. It means that both copper and phosphorus face a change of the oxidation state for the electrochemical insertion and extraction. Lithium copper phosphide exhibits a similar reaction process. However, it provides a reversible capacity of 750 mAh/g and faradic yield of 100% at the first cycle.     

Enhancement of thin film tin oxide negative electrodes for lithium batteries

Thin films of pure SnO₂, of the Sn/Li₂O layered structure, and of Sn/Li₂O were fabricated by sputtering method, while a `lithium-reacted tin oxide thin film' was assembled by the evaporation of lithium metal onto a SnO₂ thin film. Film structure and charge/discharge characteristics were compared. The lithium-reacted tin oxide thin film, the Sn/Li₂O layered structure, and the Sn/Li₂O co-sputtered thin films did not show any irreversible side reactions of forming Li₂O and metallic Sn near 0.8 V vs Li/Li⁺. The initial charge retention of the Sn/Li₂O layered structure and Sn/Li₂O co-sputtered thin films was about 50% and a similar value was found for the lithium-reacted tin oxide thin film (more than 60%). Sn/Li₂O layered structure and Sn/Li₂O co-sputtered thin films showed better cycling behavior over 500 cycles than the pure SnO₂ and lithium-reacted tin oxide thin film in the cut-off range from 1.2 to 0 V vs Li/Li⁺.     

Materials for all-solid-state thin-film rechargeable lithium batteries by sol-gel processing

A novel all-solid-state thin-film lithium battery has been fabricated by spin coating V₂O₅ and LiClO₄-SiO₂ thin films on a stainless steel substrate. The LiClO₄-SiO₂ electrolyte has been synthesized using a new sol-gel route and it has been characterized by electrochemical impedance spectroscopy. The Li⁺ ion conductivity of the spin-coated thin film thus measured is in the order of 10^–6 S/cm, at 25 °C, which is sufficient for electrolytes in such thin-film batteries. The battery shows a typical discharge capacity of about 150 μAh/mg and satisfactory cathodic efficiency and cycle-life performance. Electronic Publication     

Ionic processes in solid-electrolyte passivating films on lithium

The electrochemical behaviour of a Li electrode in solutions of LiAlCl₄ in thionyl chloride, LiBF₄ in γ-butyrolactone and LiClO₄ in the mixed solvent propylene carbonate (PC) + dimethoxyethane (DME) in the process of cell storage has been investigated by the methods of electrode impedance spectroscopy and pulse voltammetry. Analogous studies have been carried out in PC + DME solution with the Li electrode coated with a specially formed protecting film of Li₂CO₃. The results have been compared with those obtained earlier for other lithium electrochemical systems. The general regularities of the Li electrode electrochemical kinetics attributed to the process of Li⁺ ion transport through a passivating film coating a lithium surface have been discussed. Received: 22 February 1999 / Accepted: 20 June 1999