钾盐添加剂改善天然石墨负极的嵌脱锂性质

于1mol/L LiClO₄/EC+DEC电解液中添加不同的钾盐可以显著降低天然石墨电极首次循环过程中的不可逆容量损失, 提高电极的可逆容量和倍率充放电性能. 交流阻抗和电极表面固体电解质相界面(SEI)膜组分的FTIR分析表明, 添加一定量的钾盐可以降低SEI膜的锂盐含量, 有助于形成Li+迁移性良好的SEI膜.     

植酸对镁锂合金微弧氧化膜的影响

采用微弧氧化技术在镁锂合金表面制备了陶瓷膜,通过扫描电镜、X射线能谱分析、动电位极化曲线等测试技术研究了陶瓷膜的表面和截面形貌、元素组成以及耐蚀性能.采用在基本电解液里添加植酸的方法将其引入陶瓷膜,并讨论植酸质量浓度对成膜过程和陶瓷膜性能的影响.研究结果表明:陶瓷膜厚度随电解液中植酸浓度的增加而变大,膜层表面形貌逐渐改善;膜层中成功地引入了碳、磷元素,随植酸浓度增加,膜层中的碳、磷元素含量增大,镁元素含量降低;植酸的质量浓度为4g/L时所制备的陶瓷膜均匀细致,耐腐蚀性能最好.     

镁锂合金无铬阳极氧化工艺

已有的镁锂合金阳极氧化液舍Cr(Ⅵ),对环境有严重污染.研究了镁锂合金表面阳极氧化成膜工艺,使用无铬环保型电解液得到了有一定耐腐蚀性能的白色氧化膜,分析了电解液中NaOH浓度、氧化时间、电流密度等工艺参数对氧化膜的形成及其耐腐蚀性能的影响.用扫描电镜分析了氧化膜表面形貌,用交流阻抗谱和极化曲线研究了氧化膜的电化学腐蚀行为.结果表明:当电解液组成为50g/L NaOH,40g/LNa2 SiO3·9H2O,20 g/L Na2B4O7·10H2O,40 g/L C6H5Na3O7·2H2O,电流密度为10 mA/cm2,成膜时间为20min时,氧化膜的耐腐蚀性最好;经硅酸盐封孔处理氧化膜耐腐蚀性能得到了进一步提高.     

316L不锈钢在电解液中的耐蚀性能研究

为分析检测316L不锈钢在电解液中钝化膜的耐腐蚀性能,采用Tafel腐蚀极化曲线、电化学阻抗谱、Mott-Schottky进行了表征。极化曲线结果表明：腐蚀电位为-0.955 V,腐蚀电流密度为10^-4.02 A/cm²;电化学阻抗测试结果表明：当成膜电势为0.3 V时,该膜的耐蚀性能均优异于其他电势下形成的膜;由Mott-Schottky分析表明：钝化膜的施体密度基本随成膜电势的增加而降低,钝化膜的厚度基本随成膜电势增加而增加。同时,根据PDM分析可知该膜在该电解液下100 a内将被腐蚀至4.5 mm的深度。     

磷酸盐-重铬酸钾体系中钛合金微等离子体表面陶瓷化

采用微等离子体氧化技术在钛合金表面原位生长一层陶瓷膜。在以磷酸盐体系为电解液的基础之上，为进一步提高膜层的抗腐蚀性能，尝试向电解液中添加重铬酸钾，对所得陶瓷膜与前者进行比较膜的致密性增加。经XPS分析，发现膜层中磷元素增加而且有少量的铬元素出现，经循环伏安测试，表明陶瓷膜的抗点腐蚀能力明显增强，并分析了重铬酸钾对所得陶瓷膜的影响作用。     

锂离子电池硅基负极材料研究进展

锂离子电池硅基负极材料由于具有高的理论比容量,低的脱嵌锂电位,与电解液反应活性低等优点而成为研究热点。本文综述了近年来硅基材料作为锂离子负极材料的研究进展,包括纳米硅、硅基薄膜、硅-金属复合材料、硅-碳材料,分析硅基材料作为锂离子电池负极材料的研究前景和发展方向。     

新离子型添加剂对高镍锂离子电池性能影响研究

研究了一种新离子型负极成膜添加剂2D对NMC811/石墨电池性能的影响,并与当前最常用商业化负极成膜添加剂VC进行对比试验。微分容量dQ/dV显示2D先于EC和VC在2.1 V左右还原,在石墨负极形成较稳定的SEI膜,交流阻抗结果表明含2D成膜阻抗明显低于VC;含2D、VC、2D和VC复合电解液的NMC811/石墨电池的倍率循环、高温存储和高温循环等测试结果表明,含2D电解液电池的石墨负极钝化膜更加稳定,有效提升锂离子电池的循环、存储和倍率性能,60℃存储含2D电池的电压和电阻变化较小,高温循环200周后,不含2D添加剂电池容量损失达15%,含2D电池容量保持率在92%以上。     

锂离子电池硅基负极研究进展

硅由于具有超石墨10倍的高理论容量和相对适中的放电平台而备受关注,是最具潜力的下一代锂离子电池负极材料之一。然而,硅的本征电导率低,且在嵌锂的过程中有着巨大的体积变化(300%),会导致材料粉化,电极崩塌,失去电接触。此外,在电解液中硅表面的SEI膜重复形成也导致了极化增大,库伦效率降低和电解液消耗等问题。为了解决上述问题,实现硅电极的商业化应用,改善硅基电极的途径主要有:制备新型硅基材料抑制体积效应和提高电导率,改进粘结剂来加强电极结构防止电极崩塌,改进电解液以提高SEI膜质量和库伦效率。当前,改进硅基负极材料性能的主要策略是纳米化、孔隙化和复合化。粘结剂的改性也可分为开发新型粘结剂和修饰已有粘结剂。主要从硅基材料和粘结剂两方面论述了近年来的发展状况,并展望了其未来的发展方向。     

锂离子电池中电解液与石墨类负极活性材料的相容性

选择了一种具有良好贮锂结构的人造石墨试样作为锂离子电池负极活性材料，考察了它在六种不同电解液中的恒电流充、放电性能和循环伏安特性，采用傅立叶变换红外光谱分析了不同电解液在试样颗粒表面发生还原反应时所形成的固体电解质中间相膜的成份和含量。据此得出的结论是：电解液与石墨类负极活性材料能否相容的问题，实质上就是所选定的电解液能否与其颗粒表面发生缓和的还原反应、生成薄而致密的只允许锂离子通过的固体电解质中间相膜。     

热浸镀Galfan表面镧盐转化膜的生长和耐腐蚀性能的研究

在热浸镀Galfan镀层表面制备了镧盐转化膜,采用扫描电镜及能谱分析(SEM/EDS)、X射线光电子能谱分析(XPS)、原子力扫描探针显微分析(AFM)研究镧盐转化膜的表面形貌、化学成分和结构。通过中性盐雾试验、电化学极化分析和电化学阻抗研究膜层的耐腐蚀性能,确定最佳成膜时间。结果表明:镧盐转化膜成膜不均匀,优先在晶界或相界等活性区域;随着处理时间的延长,膜层的厚度增加;膜层上存在裂纹,且裂纹随着处理时间的延长而变宽,处理时间超过30 min时,膜层脱落,耐腐蚀性能降低;镧盐转化膜由La的氧化物/氢氧化物以及少量的Al和Zn的氧化物/氢氧化物组成。与未经处理的热浸镀Galfan镀层相比,镧盐转化膜显著减低基体的腐蚀速率,明显提高其耐腐蚀性能。     

Surface reaction of LiCoO2/Li system under high-voltage conditions by X-ray spectroscopy and two-dimensional correlation spectroscopy (2D-COS)

We studied the surface reactions of a LiCoO(2)/Li cell under high-voltage conditions using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and two-dimensional correlation spectroscopy (2D-COS). 2D XPS correlation spectra show that Li(2)CO(3) is formed first by decomposition of the organic solvents, and then polycarbonate, which is formed by polymerization of the electrolytes, is produced on the cathode surface of the LiCoO(2)/Li system under high-voltage conditions. XAS measurements also confirm that the solid electrolyte interface (SEI) layer is formed on the LiCoO(2) electrode by decomposition of the organic solvents. The thickness of the SEI layer is less than 100 ?.     

Distinct Solid‐Electrolyte‐Interphases on Sn (100) and (001) Electrodes Studied by Soft X‐Ray Spectroscopy

Soft X‐ray absorption spectroscopy with different probe depth was employed to characterize the solid electrolyte interphases (SEIs) formed on β‐Sn single crystals with two different surface orientations. Based on comparative studies of C‐K, O‐K, and F‐K absorption spectra between the SEIs and reference samples, SEI on Sn (100) mainly consists of porous Li₂CO₃ species with electrolyte uptake, while SEI on Sn (001) essentially consists of LiF and organic molecules, with a small amount of –CO₃ and electrolyte buried inside. Theoretical calculation suggests that Sn (001) surface is more reactive than (100), especially after air exposure. The reactive (001) surface facilitates the decomposition of LiPF₆ to form a LiF layer. In contrast, SEI on (100) surface is predominately from the typical decomposition of carbonate‐based electrolyte. While the LiF passivates Sn (001) electrode after one cycle, the porous carbonate layer on (100) surface does not prevent further decomposition of electrolyte after many cycles. This leads to drastically different electrochemical behavior and morphology of the two SEIs. The result is a direct proof that surface properties of active materials could strongly impact the SEI formation on electrodes even with the same electrolyte. Such effect could lead to distinct SEI formation and electrochemical performance.     

Tuning the Solid Electrolyte Interphase for Selective Li‐ and Na‐Ion Storage in Hard Carbon

Solid‐electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li‐ and Na‐ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li‐ or Na‐based electrolyte, and that ionic transport can be kinetically controlled. Selective Li‐ and Na‐based SEI membranes are produced using Li‐ or Na‐based electrolytes, respectively. The Na‐based SEI allows easy transport of Li ions, while the Li‐based SEI shuts off Na‐ion transport. Na‐ion storage can be manipulated by tuning the SEI layer with film‐forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g^?1; ≈ 1/10 of the normal capacity (250 mAh g^?1). Unusual selective/preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion‐selective conductors using electrochemical approaches.     

An Inorganic-Rich SEI Layer by the Catalyzed Reduction of LiNO3 Enabled by Surface-Abundant Hydrogen Bonding for Stable Lithium Metal Batteries

Lithium (Li) metal anodes (LMAs) are promising anode candidates for realizing high-energy-density batteries. However, the formation of unstable solid electrolyte interphase (SEI) layers on Li metal is harmful for stable Li cycling; hence, enhancing the physical/chemical properties of SEI layers is important for stabilizing LMAs. Herein, thiourea (TU, CH₄N₂S) is introduced as a new catalyzing agent for LiNO₃ reduction to form robust inorganic-rich SEI layers containing abundant Li₃N. Due to the unique molecular structure of TU, the TU molecules adsorb on the Cu electrode by forming Cu S bond and simultaneously form hydrogen bonding with other hydrogen bonds accepting species such as NO₃⁻ and TFSI⁻ through its N H bonds, leading to their catalyzed reduction and hence the formation of inorganic-rich SEI layer with abundant Li₃N, LiF, and Li₂S/Li₂S₂. Particularly, this TU-modified SEI layer shows a lower film resistance and better uniformity compared to the electrochemically and naturally formed SEI layers, enabling planar Li growth without any other material treatments and hence improving the cyclic stability in Li/Cu half-cells and Li@Cu/LiFePO₄ full-cells.     

High-Performance Solid Lithium Metal Batteries Enabled by LiF/LiCl/LiIn Hybrid SEI via InCl3-Driven In Situ Polymerization of 1,3-Dioxolane

The use of poly(1,3-dioxolane) (PDOL) electrolyte for lithium batteries has gained attention due to its high ionic conductivity, low cost, and potential for large-scale applications. However, its compatibility with Li metal needs improvement to build a stable solid electrolyte interface (SEI) toward metallic Li anode for practical lithium batteries. To address this concern, this study utilized a simple InCl₃-driven strategy for polymerizing DOL and building a stable LiF/LiCl/LiIn hybrid SEI, confirmed through X-ray photoelectron spectroscopy (XPS) and cryogenic-transmission electron microscopy (Cryo-TEM). Furthermore, density functional theory (DFT) calculations and finite element simulation (FES) verify that the hybrid SEI exhibits not only excellent electron insulating properties but also fast transport properties of Li⁺. Moreover, the interfacial electric field shows an even potential distribution and larger Li⁺ flux, resulting in uniform dendrite-free Li deposition. The use of the LiF/LiCl/LiIn hybrid SEI in Li/Li symmetric batteries shows steady cycling for 2000 h, without experiencing a short circuit. The hybrid SEI also provided excellent rate performance and outstanding cycling stability in LiFePO₄/Li batteries, with a high specific capacity of 123.5 mAh g⁻¹ at 10 C rate. This study contributes to the design of high-performance solid lithium metal batteries utilizing PDOL electrolytes.     

Protecting the Li‐Metal Anode in a Li–O2 Battery by using Boric Acid as an SEI‐Forming Additive

The Li–O₂ battery (LOB) is considered as a promising next‐generation energy storage device because of its high theoretic specific energy. To make a practical rechargeable LOB, it is necessary to ensure the stability of the Li anode in an oxygen atmosphere, which is extremely challenging. In this work, an effective Li‐anode protection strategy is reported by using boric acid (BA) as a solid electrolyte interface (SEI) forming additive. With the assistance of BA, a continuous and compact SEI film is formed on the Li‐metal surface in an oxygen atmosphere, which can significantly reduce unwanted side reactions and suppress the growth of Li dendrites. Such an SEI film mainly consists of nanocrystalline lithium borates connected with amorphous borates, carbonates, fluorides, and some organic compounds. It is ionically conductive and mechanically stronger than conventional SEI layer in common Li‐metal‐based batteries. With these benefits, the cycle life of LOB is elongated more than sixfold.     

Ionic conductive polymers as artificial solid electrolyte interphase films in Li metal batteries – A review

Lithium (Li) metal has been considered as the ultimate anode material for next-generation rechargeable batteries due to its ultra-high theoretical specific capacity (3860 mAh g⁻¹) and the lowest reduction voltage (−3.04 V vs the standard hydrogen electrode). However, the dendritic Li formation, uncontrolled interfacial reactions, and huge volume variations lead to unstable solid electrolyte interphase (SEI) layer, low Coulombic efficiency and hence short cycling lifetime. Designing artificial solid electrolyte interphase (artificial SEI) films on the Li metal electrode exhibits great potential to solve the aforementioned problems and enable Li–metal batteries with prolonged lifetime. Polymer materials with good ionic conductivity, superior processability and high flexibility are considered as ideal artificial SEI film materials. In this review, according to the ionic conductive groups, recent advances in polymeric artificial SEI films are summarized to afford a deep understanding of Li ion plating/stripping behavior and present design principles of high-performance artificial SEI films in achieving stable Li metal electrodes. Perspectives regarding to the future research directions of polymeric artificial SEI films for Li–metal electrode are also discussed. The insights and design principles of polymeric artificial SEI films gained in the current review will be definitely useful in achieving the Li–metal batteries with improved energy density, high safety and long cycling lifetime toward next-generation energy storage devices.     

A Stable Solid Electrolyte Interphase for Magnesium Metal Anode Evolved from a Bulky Anion Lithium Salt

Rechargeable magnesium (Mg) metal batteries are a promising candidate for “post-Li-ion batteries” due to their high capacity, high abundance, and most importantly, highly reversible and dendrite-free Mg metal anode. However, the formation of passivating surface film rather than Mg²⁺-conducting solid electrolyte interphase (SEI) on Mg anode surface has always restricted the development of rechargeable Mg batteries. A stable SEI is constructed on the surface of Mg metal anode by the partial decomposition of a pristine Li electrolyte in the electrochemical process. This Li electrolyte is easily prepared by dissolving lithium tetrakis(hexafluoroisopropyloxy)borate (Li[B(hfip)₄]) in dimethoxyethane. It is noteworthy that Mg²⁺ can be directly introduced into this Li electrolyte during the initial electrochemical cycles for in situ forming a hybrid Mg²⁺/Li⁺ electrolyte, and then the cycled electrolyte can conduct Mg-ion smoothly. The existence of this as-formed SEI blocks the further parasitic reaction of Mg metal anode with electrolyte and enables this electrolyte enduring long-term electrochemical cycles stably. This approach of constructing superior SEI on Mg anode surface and exploiting novel Mg electrolyte provides a new avenue for practical application of high-performance rechargeable Mg batteries.     

废人造石墨用作锂电池负极的表面氧化成膜改性

废人造石墨在室温下经30%的双氧水氧化, 真空干燥后进一步用LiOH浸渍处理或与Li₂CO₃共混后在N₂保护下升温处理, 在人造石墨表面形成类SEI膜用作锂离子电池的负极材料. X射线衍射和X射线光电子能谱测试分析表明, 表面氧化成膜处理使得人造石墨表面形成以Li₂CO₃为主要成分的膜层, 石墨颗粒表面的氧含量增加, 含氧官能团增多. 样品的充放电测试结果表明: 氧化成膜样品的放电容量均超过323mAh/g, 均大于处理前的255.5 mAh/g, 前50次循环的可逆放电容量基本没有衰减, 仍保持在317mAh/g以上, 说明氧化成膜处理有利于减少形成SEI膜时锂离子的消耗, 抑制溶剂和电解质的分解, 充放电效率提高.     

A Highly Reversible,Dendrite-Free Lithium Metal Anode Enabled by a Lithium-Fluoride-Enriched Interphase

Metallic lithium is the most competitive anode material for next-generation lithium (Li)-ion batteries. However, one of its major issues is Li dendrite growth and detachment, which not only causes safety issues, but also continuously consumes electrolyte and Li, leading to low coulombic efficiency (CE) and short cycle life for Li metal batteries. Herein, the Li dendrite growth of metallic lithium anode is suppressed by forming a lithium fluoride (LiF)-enriched solid electrolyte interphase (SEI) through the lithiation of surface-fluorinated mesocarbon microbeads (MCMB-F) anodes. The robust LiF-enriched SEI with high interfacial energy to Li metal effectively promotes planar growth of Li metal on the Li surface and meanwhile prevents its vertical penetration into the LiF-enriched SEI from forming Li dendrites. At a discharge capacity of 1.2 mAh cm⁻², a high CE of >99.2% for Li plating/stripping in FEC-based electrolyte is achieved within 25 cycles. Coupling the pre-lithiated MCMB-F (Li@MCMB-F) anode with a commercial LiFePO₄ cathode at the positive/negative (P/N) capacity ratio of 1:1, the LiFePO₄//Li@MCMB-F cells can be charged/discharged at a high areal capacity of 2.4 mAh cm⁻² for 110 times at a negligible capacity decay of 0.01% per cycle.