In Situ Electropolymerization Enables Ultrafast Long Cycle Life and High-Voltage Organic Cathodes for Lithium Batteries

Organic cathode materials have attracted extensive attention because of their diverse structures, facile synthesis, and environmental friendliness. However, they often suffer from insufficient cycling stability caused by the dissolution problem, poor rate performance, and low voltages. An in situ electropolymerization method was developed to stabilize and enhance organic cathodes for lithium batteries. 4,4′,4′′-Tris(carbazol-9-yl)-triphenylamine (TCTA) was employed because carbazole groups can be polymerized under an electric field and they may serve as high-voltage redox-active centers. The electropolymerized TCTA electrodes demonstrated excellent electrochemical performance with a high discharge voltage of 3.95 V, ultrafast rate capability of 20 A g⁻¹, and a long cycle life of 5000 cycles. Our findings provide a new strategy to address the dissolution issue and they explore the molecular design of organic electrode materials for use in rechargeable batteries.     

Light/Electricity Energy Conversion and Storage for a Hierarchical Porous In2S3@CNT/SS Cathode towards a Flexible Li-CO2 Battery

A photoinduced flexible Li-CO₂ battery with well-designed, hierarchical porous, and free-standing In₂S₃@CNT/SS (ICS) as a bifunctional photoelectrode to accelerate both the CO₂ reduction and evolution reactions (CDRR and CDER) is presented. The photoinduced Li-CO₂ battery achieved a record-high discharge voltage of 3.14 V, surpassing the thermodynamic limit of 2.80 V, and an ultra-low charge voltage of 3.20 V, achieving a round trip efficiency of 98.1 %, which is the highest value ever reported (<80 %) so far. These excellent properties can be ascribed to the hierarchical porous and free-standing structure of ICS, as well as the key role of photogenerated electrons and holes during discharging and charging processes. A mechanism is proposed for pre-activating CO₂ by reducing In³⁺ to In⁺ under light illumination. The mechanism of the bifunctional light-assisted process provides insight into photoinduced Li-CO₂ batteries and contributes to resolving the major setbacks of the system.     

高比能锂离子电池层状富锂正极材料改性策略研究进展

层状富锂材料具有超过250 mAh∙g⁻¹的高可逆比容量,被认为是下一代高比能锂离子电池最具商业化前景的正极材料之一。然而,层状富锂材料在实际应用之前仍需解决诸多挑战,如高电压氧释放、层状到岩盐相的结构变化、过渡金属离子迁移等结构劣化,并由此带来了较低的初始库伦效率、电压/容量的衰减以及循环寿命的不足。针对以上问题,进行层状富锂材料改性无疑是一种行之有效的方法。本综述全面介绍了层状富锂材料的结构、组分以及电化学性能,在此基础上对材料改性策略进行了系统阐述,详细介绍了体相掺杂、表面包覆、缺陷设计、离子交换和微结构调控等一系列改性策略的现状以及发展趋势,最终提出了高容量和长循环层状富锂材料和高比能锂离子电池的设计思路。     

Revealing the Reaction and Fading Mechanism of FeSe2 Cathodes for Rechargeable Magnesium Batteries

Rechargeable Mg batteries (RMBs) are advantageous large-scale energy-storage devices because of the high abundance and high safety, but exploring high-performance cathodes remains the largest difficulty for their development. Compared with oxides and sulfides, selenides show better Mg-storage performance because the weaker interaction with the Mg²⁺ cation favors fast kinetics. Herein, nanorod-like FeSe₂ was synthesized and investigated as a cathode for RMBs. Compared with microspheres and microparticles, nanorods exhibit higher capacity and better rate capability with a smaller particle size. The FeSe₂ nanorods show a high capacity of 191 mAh g⁻¹ at 50 mA g⁻¹ and a good rate performance of 39 mAh g⁻¹ at 1000 mA g⁻¹. Ex situ characterizations demonstrate the Mg²⁺ intercalation mechanism for FeSe₂, and a slight conversion reaction occurs on the surface of the particles. The capacity fading is mainly because of the dissolution of Fe²⁺, which is caused by the reaction between Fe²⁺ and Cl⁻ of the electrolyte during the charge process on the surface of the particles. The surface of FeSe₂ is mainly selenium after long cycling, which may also dissolve in the electrolyte during cycling. The present work develops a new type of Mg²⁺ intercalation cathode for RMBs. More importantly, the fading mechanism revealed herein has considered the specificity of Mg battery electrolyte and would assist a better understanding of selenide cathodes for RMBs.     

Ozone-based electrochemical advanced oxidation processes

Novel processes have recently been developed that provide for the enhancement of ozonation through combination with electrochemical treatments. These are processes that can be included among those defined as advanced oxidation processes as they proceed via electrogeneration of highly oxidizing radical species.These processes are generally carried out by sparging ozone in both divided and undivided electrochemical cells in order to promote its decomposition through different mechanisms, depending on the electrode materials adopted, and in some cases still debated.This mini review presents the most recent advances in the field of electrochemically assisted ozonation.In particular, the first section is focused on the process known as electroperoxone (EP) where the ozone decomposition is enhanced by the adoption of carbon-based cathodes, due to the electrogeneration of hydrogen peroxide, while the second section is focused on the process that implies ozonation in a cell adopting metal-based cathodes.     

熔盐法合成电化学性能优异的富锂层状正极材料Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5)

采用氢氧化物共沉淀和熔盐法相结合的方法制备得到了电化学性能优异的富锂锰基Li_(1.5)Ni_(0.25)Mn_(0.75)O_(2.5)正极材料。借助X射线衍射(XRD)分析、扫描电镜(SEM)、感应耦合等离子体原子发射光谱(ICP-AES)、X射线光电子能谱(XPS)、电化学阻抗谱(EIS)和恒电流充放电测试等表征手段对材料的颗粒形貌、晶体结构和电化学性能进行了系统研究。XRD结果表明该材料具有完善的α-NaFeO2层状结构(空间群为R3m)和较低的Li~+/Ni~(2+)阳离子混排。电化学性能测试表明该材料的首次不可逆容量损失较小,且倍率性能和循环稳定性能十分优异。具体而言,在2.0~4.8V,0.1C时的首次不可逆容量损失为50mAh·g~(-1)(首次库伦效率84%);在10C时的放电比容量还能达到102mAh·g~(-1);在0.5C下循环100次后,放电比容量为205mAh·g~(-1)(容量保持率90%)。     

Development of Magnesium Anode-Based Transient Primary Batteries

Biodegradable primary batteries, also known as transient batteries, are essential to realize autonomous biodegradable electronic devices with high performance and advanced functionality. In this work, magnesium, copper, iron, and zinc – metals that exist as trace elements in the human body – were tested as materials for biomedical transient electronic devices. Different full cell combinations of Mg and X (where X = Cu, Fe, and Zn and the anodized form of the metals) with phosphate buffered saline (PBS) as electrolyte were studied. To form the cathodes, metal foils were anodized galvanostatically at a current density of 2.0 mA cm⁻² for 30 mins. Electrochemical measurements were then conducted for each electrode combination to evaluate full cell battery performance. Results showed that the Mg−Cu_anodized chemistry has the highest power density at 0.99 mW/cm². Nominal operating voltages of 1.26 V for the first 0.50 h and 0.63 V for the next 3.7 h were observed for Mg−Cu_anodized which was discharged at a current density of 0.70 mA cm⁻². Among the materials tested, Mg−Cu_anodized exhibited the best discharge performance with an average specific capacity of 2.94 mAh cm⁻², which is comparable to previous reports on transient batteries.     

富锂正极材料Li[Li0.2Mn0.4Fe0.4]O2的表面包覆改性

用共沉淀法合成了富锂正极材料Li[Li0.2Mn0.4Fe0.4]O2,并对其表面进行Al2O3包覆。采用XRD、SEM和电化学测试等方法对样品进行表征。结果表明,与Li[Li0.2Mn0.4Fe0.4]O2相比,包覆改性后的Li[Li0.2Mn0.4Fe0.4]O2具有较好的电化学性能,其初始放电容量未明显降低,而循环寿命大大提高,4.0%Al2O3包覆处理的富锂正极材料经50次充放电循环后,容量衰减量在9%左右。     

Erosion of Thin Foils by Sputtering in Hollow Cathodes

A thin copper foil placed diagonally in a cylindrical copper hollow cathode undergoes fast erosion caused by cathode sputtering. Changes in the foil shape are related to current distribution along the hollow cathode axis. The experimental results aid in understanding the increase in spectral lines intensities emitted from conical bottom hollow cathode lamps.     

Fervent Hype behind Magnesium Batteries: An Open Call to Synthetic Chemists—Electrolytes and Cathodes Needed

Magnesium metal is a superior anode which has double the volumetric capacity of lithium metal and has a negative reduction potential of −2.37 V vs. the standard hydrogen electrode. A major benefit of magnesium is the apparent lack of dendrite formation during charging which is one of the crucial concerns of using a lithium metal anode. In this Review, we highlight the foremost research in the development of electrolytes and cathodes and discuss some of the significant challenges which must be overcome in realizing a practical magnesium battery.