集流体对可充镁电池电解液电化学性能的影响

系统研究了铂、镍、不锈钢(SS)、铜、铝五种金属集流体和碳纤维、石墨箔、碳布三种碳纸集流体对“一代” (Mg(AlCl₂BuEt)₂/THF)、“二代” ((PhMgCl)₂-AlCl₃/THF)可充镁电池电解液阳极氧化分解电位和镁沉积-溶出性能的影响。金属镍、不锈钢、铜、铝作为可充镁电池正极的集流体时, 充电至一定电压时自身均会发生腐蚀。其中, 镍和不锈钢可用作充电电压在2.1V(vs Mg/Mg²⁺)以下正极材料的集流体; 铜可用作充电电压在1.8V(vs Mg/Mg²⁺)以下正极材料的集流体。碳集流体比金属集流体具有更高的稳定性, 其中, 碳布作为集流体, 适用于充电电压在2.25V(vs. Mg)(对“一代”电解液)和2.95V(vs Mg/Mg²⁺)(对“二代”电解液)以下的正极材料。     

Rapid evaluation of the rechargeability of c-MnO2 in alkaline media by abrasive stripping voltammetry

Cyclic abrasive stripping voltammetry is shown to provide the experimental basis for the evaluation of the rechargeability of γ-MnO₂ in 9 M KOH. Relative discharge capacities at different depths of discharge (DOD) with respect to the first one-electron reduction of γ-MnO₂ are compared when metal ions such as Ba²⁺ or Zn²⁺ are additionally present in the electrolyte solution. At about 30% DOD, resulting relative discharge capacities are essentially equal to those of AA cells either in the absence or presence of Ba²⁺ ions from about 10 discharge/charge cycles. However, the corresponding time scales are substantially different. While it takes about 2.7 h to complete 20 discharge/charge cycles in the case of abrasive stripping voltammetric characterization, some 360 h are needed to cycle an AA-sized battery in the conventional manner. Received: 25 November 1997 / Accepted: 20 January 1998     

First-principles calculations of the effect of Ge content on the electronic,mechanical and acoustic properties of Li17Si4-xGex

The electronic, mechanical and acoustic properties of Li₁₇Si_4-xGe_x (x = 0, 2.3, 3.08, 3.53, and 4) have been investigated by using first-principles calculations based on the density functional theory (DFT). The research shows that the bulk modulus B, Young's modulus E, shear modulus G, and hardness H_v gradually decrease with the increasing Ge content. Li₁₇Si_4-xGe_x have the brittle nature from the analysis of B/G ratio and Cauchy pressure. The maximum Young's moduli are all along [1 1 0] plane, and the sequence of degree of anisotropic property is Li₁₇Ge₄ > Li₁₇Si_0.48Ge_3.52 > Li₁₇Si_0.92Ge_3.08 > Li₁₇Si_1.7Ge_2.3 > Li₁₇Si₄. The analysis of acoustic velocity shows that all the sound velocities decrease with the increasing Ge content for Li₁₇Si_4-xGe_x (x = 0, 2.3, 3.08, 3.53, and 4), and the longitudinal wave along [111] direction is fastest for the studied compounds. Debye temperature Θ_D, v_t and v_l decrease with the increasing Ge content. The minimum thermal conductivity decreases with the increasing Ge content, and Li₁₇Si_4-xGe_x have low thermal conductivities and are not potential thermal conductors. The analysis of electronic properties indicates that Li₁₇Si_4-xGe_x have the metal nature and anisotropic electrical conductivity. The electric conduction is improved with the increasing Ge content.     

Mutual indirect probing of platinized platinum/tungstate nanostructural features

The comparative study of isopolytungstates immobilized on smooth Pt and platinized Pt (Pt/Pt) provides a possibility to separate several specific effects on H- and O-upd at an external platinum surface and inside the pores of Pt/Pt. In the former case, a solid rechargeable product is formed (nonstoichiometric tungsten bronze), which an inherent porous structure allows solution penetration and does not prevent charging of the Pt/solution interface. Electrochemical responses of smooth Pt give more precise information on the film behaviour, when adsorption phenomena are clarified on the basis of data for Pt/Pt. Electrocatalytic tests (nitrate reduction) confirm unambiguously that the major part of the internal Pt/Pt surface area is modified by adsorbed polytungstate. This result gives, in its turn, new understanding of the size of Pt/Pt pores on the nanometre scale.

导电含硫材料/聚苯胺复合物作为镁二次电池的正极材料

使用通过简单加热聚丙烯腈(PAN)和硫单质而得到的导电含硫材料(conductive sulfur-containing material, CSM)及其与聚苯胺(PAn)的复合物作为镁二次电池的正极材料. X射线衍射(XRD)和傅立叶红外光谱(FT-IR)测试表明, 导电含硫材料的结构由类似石墨的微晶相及无定形相所组成, 材料骨架为含有S—S键的脱水嘧啶型基质. 该导电含硫材料与聚苯胺复合并掺杂Cu(II)后, 其放电比容量和电化学可逆性大大提高, 放电比容量可达117.3 mAh·g-1, 22次循环后容量保持大约78％(相对于第二次放电容量). 聚苯胺不仅起到电化学催化剂的作用, 同时也是电极活性物质, 并且在分子水平上改善了活性材料的导电性能. 该复合物研究结果为镁二次电池正极材料结构设计的开发提供了新的思路.     

Preparation and electrochemical study of a new magnesium intercalation material Mg1.03Mn0.97SiO4

Orthorhombic magnesium manganese silicate (Mg_1.03Mn_0.97SiO₄) was prepared and evaluated as a new cathode material for rechargeable magnesium batteries. Although the electrochemical activity of the Mg_1.03Mn_0.97SiO₄ synthesized by high-temperature solid-state reaction is low, the magnesium storage capacity of nanosized Mg_1.03Mn_0.97SiO₄ prepared by modified sol–gel route and in situ carbon coating reaches 244 mAh g⁻¹. The capacity increase mechanism during charge/discharge cycling was also preliminary studied.     

Empowering Zn Electrode Current Capability Along Interfacial Stability by Optimizing Intrinsic Safe Organic Electrolytes

Metallic Zn is one of the most promising anodes, but its practical application has been hindered by dendritic growth and serious interfacial reactions in conventional electrolytes. Herein, ionic liquids are adopted to prepare intrinsically safe electrolytes via combining with TEP or TMP solvents. With this synergy effect, the blends of TEP/TMP with an IL fraction of ≈25 wt% are found to be promising electrolytes, with ionic conductivities comparable to those of standard phosphate-based electrolytes while electrochemical stabilities are considerably improved; over 1000 h at 2.0 mA cm⁻² and ≈350 h at 5.0 mA cm⁻² with a large areal capacity of 10 mAh cm⁻². The use of functionalized IL turns out to be a key factor in enhancing the Zn²⁺ transport due to the interaction of Zn²⁺ ions with IL-zincophilic sites resulting in reduced interfacial resistance between the electrodes and electrolyte upon cycling leading to spongy-like highly porous, homogeneous, and dendrite-free zinc as an anode material.     

Rechargeable Biomass Battery for Electricity Storage/generation and Concurrent Valuable Chemicals Production

The development of a rechargeable battery that can produce valuable chemicals in both electricity storage and generation processes holds great promise for increasing the electron economy and economic value. However, this battery has yet to be explored. Herein, we report a biomass flow battery that generates electricity while producing furoic acid, and store electricity while yielding furfuryl alcohol. The battery is composed of a rhodium-copper (Rh₁Cu) single-atom alloy as anode, a cobalt-doped nickel hydroxide (Co_0.2Ni_0.8(OH)₂) as cathode, and furfural-containing anolyte. In a full battery evaluation, this battery displays an open circuit voltage (OCV) of 1.29 V and a peak power density up to 107 mW cm⁻², surpassing most catalysis-battery hybrid systems. As a proof-of-concept, we demonstrate that this battery produces 1 kg furoic acid with 0.78 kWh electricity output, and yields 0.62 kg furfuryl alcohol when 1 kWh electricity is stored. This work may shed light on the design of rechargeable batteries with value-added functionality such as chemicals production.     

Free-standing vanadium pentoxide nanoribbon film as a high-performance cathode for rechargeable sodium batteries

Vanadium pentoxide(V_2O_5·nH_2O) nanoribbons are synthesized via a hydrothermal process. These ribbons are 20 nm thick, 200 nm to 1 μm wide and several tens of micrometers long. Free-standing binder-free films are prepared by using these nanoribbons with multi-walled carbon nanotubes(MWCNTs) and used as the cathode for rechargeable sodium batteries. The large interlayer space between the V_2O_5 bilayers can enhance the kinetics of sodium ion intercalation/deintercalation. In addition, the intertwining network of the V_2O_5·0.34 H_2O film provides efficient electron conduction pathways and shortens diffusion distances of sodium ion. The electrochemical tests prove that the freestanding V_2O_5 · 0.34 H_2O film cathode delivers high reversible specific capacities(190 mAh/g) and good cycling stabilities(170 mAh/g after 150 cycles) in the voltage range between 1.5 V and 3.5 V.     

Strategies of Removing Residual Lithium Compounds on the Surface of Ni‐Rich Cathode Materials†

Ni‐rich cathode materials have become one of the most promising cathode materials for advanced high‐energy Li‐ion batteries (LIBs) owing to their high specific capacity. However, Ni‐rich cathode materials are sensitive to the trace H₂O and CO₂ in the air, and tend to react with them to generate LiOH and Li₂CO₃ at the particle surface region (named residual lithium compounds, labeled as RLCs). The RLCs will deteriorate the comprehensive performances of Ni‐rich cathode materials and make trouble in the subsequent manufacturing process of electrode, including causing low initial coulombic efficiency and poor storage property, bringing about potential safety hazards, and gelatinizing the electrode slurry. Therefore, it is of considerable significance to remove the RLCs. Researchers have done a lot of work on the corresponding field, such as exploring the formation mechanism and elimination methods. This paper investigates the origin of the surface residual lithium compounds on Ni‐rich cathode materials, analyzes their adverse effects on the performance and the subsequent electrode production process, and summarizes various kinds of feasible methods for removing the RLCs. Finally, we propose a new research direction of eliminating the lithium residuals after comparing and summing up the above. We hope this work can provide a reference for alleviating the adverse effects of residual lithium compounds for Ni‐rich cathode materials’ industrial production.