基于三维亲锂材料的高稳定金属锂负极的构筑

金属锂具有超高理论比容量密度(3680 mA·h·g^?1)和低还原电位(?3.04 V vs.SHE),被认为是高能量密度电池负极材料的“圣杯”.然而,由于锂枝晶不可控生长和对电解质高反应性导致的库仑效率低、循环寿命短及内短路等问题严重制约着金属锂负极的实用化进展.在实际的电化学体系中,集流体作为金属锂沉积/脱出的基底,其表面性质对锂负极的循环稳定性起着至关重要的作用.本文从负极、集流体表面成分以及微结构设计两方面系统总结了构建三维亲锂骨架材料的改性策略.利用金属、金属氧化物、杂原子掺杂、聚合物材料及有机框架材料等高亲锂材料对集流体和负极的界面及结构进行针对性调控修饰,可以有效调控金属锂的电沉积,推进金属锂负极在高能量密度电池体系中的实用化进程.     

亲锂的三维二硫化锡@碳纤维布用于稳定的锂金属负极

金属锂由于其高的比容量,低的电极电势和轻质等特点被认为是下一代高能量密度锂金属二次电池负极材料的最佳选择。然而,充放电循环中不均匀的锂沉积会导致严重的体积变化和大量的锂枝晶形成,从而影响了电池的库伦效率甚至会带来严重的安全隐患。为此,本文设计了一种亲锂的三维二硫化锡@碳纤维布复合基底材料,并作为集流体将其应用于金属锂电池上。一者,高比表面积的三维碳纤维骨架可以适应充放电过程中的体积变化并且有效地降低局部电流密度,从而确保锂的均匀沉积。二者,表面修饰的SnS2层在锂沉积过程中可以形成Li-Sn合金界面层,诱导锂的沉积并降低过电势。最终,实验结果表明:使用所制备的复合集流体与金属锂搭配组成的半电池可以在5 mA·cm^-2的高电流密度下以>98%的库伦效率稳定循环100周以上。此外,在承载10 mAh·cm^-2的金属锂后,复合的锂负极无论是在对称电池还是与磷酸铁锂组装成的实际电池中,均可以在高的电流密度下实现稳定的循环。我们相信这一复合的集流体构建策略对于设计安全稳定的锂金属电池或器件具有重要意义。     

热熔灌输法制备三维骨架支撑金属锂复合负极

金属锂因具有极高的理论比容量(3860 mAh/g)和最低的电化学势(相对于标准氢电极为-3.04 V),被认为是下一代高比能锂离子电池的首选负极材料。然而,金属锂负极在电池循环过程中发生的刺状枝晶生长和体积变化等问题严重阻碍了其产业化应用进程。近年来研究表明,通过在金属锂中引入具有三维(3D)结构的宿主骨架,不但能有效抑制锂枝晶的生长,而且可以缓解金属锂负极的体积变化,从而提高金属锂电池的循环性能与安全性。因此,设计3D骨架/金属锂复合负极被认为是一种能有效解决金属锂问题的新兴策略。本文综述了热熔灌输法制备3D骨架/金属锂复合负极的研究进展。首先讨论了当前基于3D骨架的预存金属锂技术,然后着重分析了热熔灌输策略中3D骨架锂润湿性的影响因素,以及不同3D骨架修饰特征和改性方法。最后对3D骨架/金属锂复合负极和热熔灌输策略现存问题进行了总结并提出未来的发展方向。     

基于三维集流体的无枝晶锂金属负极

随着电化学储能市场的迅猛发展, 当前商用锂离子电池难以满足人们对高能量密度储能器件的需求. 锂金属具有高比容量和低氧化还原电位等优点, 被认为是下一代二次电池的理想负极材料. 然而, 锂金属负极在充放电过程中会出现体积变化大、 枝晶生长、 界面不稳定等问题, 严重阻碍了其在二次电池中的实际应用. 三维多孔材料具有骨架/空间互穿网络结构、 比表面积大、 孔隙发达和机械性能好等物理特性, 用作金属锂负极的集流体, 在锂沉积/溶解过程中可以起到降低局部有效电流密度、 均匀电场分布和降低锂离子浓度梯度的作用, 有望实现锂的均匀成核和无枝晶沉积, 同时抑制了电极的体积膨胀. 尽管有关三维集流体的研究报道不断出现, 但综合系统评价现有各种三维集流体体系的工作鲜见报道. 本文聚焦锂金属负极三维集流体的构建及应用研究进展, 首先分析了三维集流体抑制锂枝晶生长的基本原理及局限性, 继而重点关注了三维集流体的结构调控、 表面改性和功能化等应对策略对锂成核、 沉积过程的影响, 并对不同材质三维集流体的优缺点进行了归纳总结. 最后, 面向实用化, 分析并展望了三维集流体应用于锂金属电池的发展前景.     

三维大孔/介孔碳-碳化钛复合材料用于无枝晶锂金属负极

金属锂具有超高的理论容量(3860 mAh·g^-1)和低氧化还原电位(-3.04 V vs.标准氢电极),是极具吸引力的下一代高能量密度电池的负极材料。然而,循环过程中的体积膨胀、锂枝晶生长和“死锂”等问题严重的限制了其实际应用。合理设计三维骨架调控金属锂的成核行为是抑制锂枝晶生长的有效策略。本文中,我们发展了一种“软硬双模板”的方法合成了兼具大孔和介孔的三维碳-碳化钛(Three-dimensional macro-/mesoporous C-TiC,表示为3DMM-C-TiC)复合材料。多级孔道为金属锂的沉积提供了足够的空间,缓冲充放电中巨大的体积变化。此外,TiC的引入显著增强多孔骨架的导电性,改善锂金属的成核行为,促进金属锂的均匀成核和沉积,抑制锂枝晶生长。3DMM-C-TiC||Li电池测试表明,在循环300圈以后,库伦效率仍保持在98%以上。此外,所得材料与LiFePO₄ (LFP)组成的全电池也表现出优异的倍率和循环性能。本工作为无枝晶锂金属负极的设计提供了新的思路。     

三维铜基集流体的构筑及在锂金属电池中的应用

锂金属因其具有超高比容量(3860 mAh·g^-1)以及较低的氧化还原电势(-3.04 V vs 标准氢电极),被认为是下一代高能量密度二次电池的理想负极材料。然而“无宿主”的金属锂在金属/电解液界面层进行沉积/剥离,不可避免地会生长枝晶,不仅使电极表面电流分布不均,同时可能会刺穿电池隔膜而导致电池短路。通过构造三维集流体/锂金属复合负极可以有效调控锂沉积行为并抑制枝晶生长,从而提升电池的库仑效率、循环寿命以及倍率性能,该领域近年来一直都是研究的热点。本文首先总结了基于三维集流体抑制锂枝晶的相关原理和模型;其次针对用于负极的铜基集流体,根据构成三维结构基底单元的维度,总结了三维铜基集流体的制备方法及其在锂金属负极保护方面的应用;最后,对三维集流体构造复合锂负极进行了总结和展望。     

功能化固态电解质膜改性锂金属负极的研究进展

对高比能量锂离子电池需求的不断增加激发了锂金属负极的应用研究。锂金属具有高放电比容量(3860 mAh·g^?1),低电极电位(?3.04 V),是锂离子电池的理想负极材料。然而,锂金属在循环过程中会形成不稳定的固态电解质(SEI)膜,而且会生成枝晶,枝晶的生长会引发电池短路等安全问题,极大地阻碍了其应用。理想的SEI膜应具有良好的锂离子传导性、表面电子绝缘性和机械强度,可调控锂离子在表面均匀沉积,促进离子传输,抑制枝晶生长,因此构筑功能化SEI膜是解决锂金属负极所面临挑战的一项有效策略。本综述以锂金属枝晶形成和生长的机理为出发点,分析总结SEI膜的构建策略、不同组成SEI膜的结构和功能特性及其对锂金属负极性能的影响,并对锂金属实用化面临的挑战及未来发展方向进行了展望。     

锂金属负极人造保护膜的研究进展

金属锂因其具有极高的理论容量(3860 mAh·g^?1)、最低的电极电位(?3.04 V vs.标准氢电极)和低的密度(0.534 g·cm^?3),被认为是最具潜力的负极材料。但循环过程中不可控的枝晶生长及不稳定的固体电解质相界面膜所引起的安全隐患和电池库伦效率低等问题严重阻碍了锂金属负极的发展。通过在电极表面构建人造保护膜可以有效调控锂离子沉积行为,因此人造保护膜的构建是一种简单高效抑制锂枝晶生长的策略。本综述将从聚合物保护膜、无机保护膜、有机-无机复合保护膜和合金保护膜总结了人造保护膜的构建方法、抑制锂枝晶生长机理,为促进高比能锂金属电池的商业化应用提供借鉴参考作用。     

多孔金属有机框架材料作为锂金属负极保护层助力长寿命锂氧气电池

在众多能源储存系统中,锂氧气电池以其高达3500 Wh·kg^-1的理论能量密度有望在性能上超越商用锂离子电池.然而,在电池充放电过程中,金属锂不可控的枝晶生长和严重的腐蚀问题极大地阻碍了锂氧气电池的发展.为了解决以上问题,制备了一种具有高比表面积、丰富孔道结构的金属有机框架材料（MOF-801）,并将其设计成金属锂负极的保护层应用在锂氧气电池中.在本工作中,成功合成了具有高达762.9 m²·g^-1比表面积,边长约为800 nm的立方体状纯净MOF-801材料.并且这种材料表现出对于有机电解液体系（四乙二醇二甲醚1 mol·L^-1三氟甲基磺酸锂）和强还原性的金属锂都具有很好的稳定性.得益于该材料丰富的孔道结构以及高比表面积,锂离子得以更均匀地分布在电极表面促进金属锂均匀沉积,有效避免了由于枝晶刺破隔膜而导致的短路甚至火灾事故.此外,MOF-801保护层本身的阻隔作用和材料捕捉水的特性可以帮助减少污染物质（水、氧气、强氧化性物质等）的穿梭效应带来的副反应,缓解锂氧气电池中金属锂负极的腐蚀情况.因此,将经过保护的金属锂组装成的对称电池进行测试,循环寿命长达800 h,同时充/放电过电势仅为0.023 V（未经保护的电池寿命仅为254 h,最终充/放电过电势高达5 V）,且循环阻抗大大降低,证明了这种策略有效地稳定了金属锂/电解液界面.将经过MOF材料保护的电极实际应用在锂氧气电池中,在限容量1000 mAh·g^-1,限电流500 mA·g^-1条件下,可以实现长达170圈的稳定长寿命的循环（是未经保护的电池寿命的2.88倍）.使用MOF-801保护层的锂氧气电池还表现出了高达8935 mAh·g^-1的高比容量.因此,本工作所报道的保护层策略为未来的碱金属空气电池负极保护领域提供了新颖的视角.     

追踪锂金属负极的压力与形貌变化（英文）

采用高载量氧化物正极(>4mAh·cm^-2)和超薄锂金属负极(<50μm)可以构建高比能锂金属二次电池。然而,该类电池的循环寿命和安全性受到锂金属不可控沉积的严重制约。高比表面积的锂枝晶和锂“苔藓”导致了较低的库伦效率,前者有一定可能穿刺隔膜,造成电池内短路,是亟待解决的安全隐患。因此,提升锂金属二次电池的循环寿命和安全性的关键在于实现锂金属的致密沉积。文献中已有多种化学方法可达到这样的效果。由于锂金属较软,受力容易发生形变,对锂金属电池施加机械压力是另一种促进锂金属致密沉积和提高循环性能的方法。然而,机械压力、锂金属形态的演变、和循环性能之间的关系尚未被完全理解。本文报道了一种基于薄膜压力传感器的电池压力测量装置,可以实时跟踪纽扣型锂金属电池内部的压力变化,并且探究外加机械压力对电池循环性能的影响。研究发现,在纽扣电池和高比能的软包电池(5 Ah,>380 Wh·kg^-1)中,一定程度的压力可以促进锂金属的致密沉积,改善电池循环性能;而过大的压力则会导致锂金属向负极内部沉积,造成负极变形和电池性能恶化。我们的研究结果凸显了...     

Lithiophilic Sites in Doped Graphene Guide Uniform Lithium Nucleation for Dendrite-Free Lithium Metal Anodes

Lithium (Li) metal is the most promising electrode for next-generation rechargeable batteries. However, the challenges induced by Li dendrites on a working Li metal anode hinder the practical applications of Li metal batteries. Herein, nitrogen (N) doped graphene was adopted as the Li plating matrix to regulate Li metal nucleation and suppress dendrite growth. The N-containing functional groups, such as pyridinic and pyrrolic nitrogen in the N-doped graphene, are lithiophilic, which guide the metallic Li nucleation causing the metal to distribute uniformly on the anode surface. As a result, the N-doped graphene modified Li metal anode exhibits a dendrite-free morphology during repeated Li plating and demonstrates a high Coulombic efficiency of 98 % for near 200 cycles.     

Lithiophilic Sites in Doped Graphene Guide Uniform Lithium Nucleation for Dendrite‐Free Lithium Metal Anodes

Lithium (Li) metal is the most promising electrode for next‐generation rechargeable batteries. However, the challenges induced by Li dendrites on a working Li metal anode hinder the practical applications of Li metal batteries. Herein, nitrogen (N) doped graphene was adopted as the Li plating matrix to regulate Li metal nucleation and suppress dendrite growth. The N‐containing functional groups, such as pyridinic and pyrrolic nitrogen in the N‐doped graphene, are lithiophilic, which guide the metallic Li nucleation causing the metal to distribute uniformly on the anode surface. As a result, the N‐doped graphene modified Li metal anode exhibits a dendrite‐free morphology during repeated Li plating and demonstrates a high Coulombic efficiency of 98 % for near 200 cycles.     

锂金属负极的挑战与改善策略研究进展

锂金属由于其高比容量和低电极电势等优点被认为是下一代高比能量电池体系中最有潜力的负极材料。然而由于锂金属的高活性,锂负极在循环过程中会产生大量的枝晶,导致SEI(solid-electrolyte interphase)破裂,并且枝晶增加了电极与电解液的接触面积,使得副反应进一步增加。此外,脱落的枝晶形成死锂,从而降低电池的充放电库仑效率。并且不可控的锂枝晶持续生长会刺穿隔膜引发电池短路,伴随着电池热失控等安全问题。本综述基于锂负极存在的主要挑战,结合理解锂枝晶的成核生长模型等机理总结并深度分析近些年来在液态和固态电解质体系中改善锂金属负极的主要策略及其作用机理,为促进高比能量锂金属电池的应用提供借鉴参考作用。     

Three-Dimensional Graphene/Ag Aerogel for Durable and Stable Li Metal Anodes in Carbonate-Based Electrolytes

The use of Li metal as the anode for Li-based batteries has attracted considerable attention due to its ultrahigh energy density. However, the formation of Li dendrites, uneven deposition, and huge volume changes hinder its reliable implementation. These issues become much more severe in commercial carbonate-based electrolytes than in ether-based electrolytes. Herein, a rationally designed three-dimensional graphene/Ag aerogel (3D G-Ag aerogel) is proposed for Li metal anodes with long cycle life in carbonate-based electrolytes. The modified lithiophilic nature of G-Ag aerogel, realized through decoration with Ag NPs, effectively decreases the energy barrier for Li nucleation, regulating uniform Li deposition behavior. Moreover, the highly flexible, conductive 3D porous architecture with hierarchical mesopores and macropores can readily accommodate deposited Li and ensures the integrity of the conductive network during cycling. Consequently, high coulombic efficiency (over 93.5 %) and a significantly long cycle life (1589 h) over 200 cycles, with a relatively high cycling capacity of 2.0 mAh cm⁻², can easily be achieved, even in a carbonate-based electrolyte. Considering the intrinsic high voltage windows of carbonate-based electrolytes, matching the G-Ag aerogel Li metal anode with a high-voltage cathode can be envisaged for the fabrication of high-energy-density Li secondary batteries.     

基于表界面反应及优化的锂金属电池研究进展

金属锂具有高理论比容量和低还原电位, 是锂电池阳极的理想材料之一. 但在长期循环充放电过程中, 金属锂因锂枝晶生长会导致出现界面恶化及能量损失严重等问题, 对锂金属电极与电解质表界面反应的优化是一个重要研究方向. 本文介绍了锂枝晶产生的危害, 从分析及抑制锂枝晶沉积两方面综合评述了为解决这一问题所采取的方法, 包括固态电解质界面形成机制和保护机理、 表面改性、 三维锂阳极和液态/固态电解质等方法, 总结了各种方法的优劣势, 并展望锂金属电池在能源领域的研究前景.     

Engineering Bifunctional Host Materials of Sulfur and Lithium-Metal Based on Nitrogen-Enriched Polyacrylonitrile for Li–S Batteries

Lithium–sulfur batteries (LSBs) still suffer from the shuttle effect on the cathode and the lithium dendrite on the anode. Herein, polyacrylonitrile (PAN) is developed into a bifunctional host material to simultaneously address the challenges faced on both the sulfur cathode and lithium anode in LSBs. For the sulfur cathode, PAN is bonded with sulfur to produce sulfurized PAN (SPAN) to avoid the shuttle effect. The SPAN is accommodated into a conductive 3D CNTs-wrapped carbon foam to prepare a self-supporting cathode, which improves the electronic and ionic conductivity, and buffers the volume expansion. Thereby, it delivers reversible capacity, superb rate capability, and outstanding cycling stability. For the Li-metal anode, PAN aerogel is carbonized to give macroporous N-doped cross-linked carbon nanofiber that behaves as a lithiophilic host to regulate Li plating and suppress the growth of Li dendrite. Combining the improvements for both the cathode and anode realizes a remarkable long-term cyclability (765 mAh g⁻¹ after 300 cycles) in a full cell. It provides new opportunity to propel the practical application of advanced LSBs.     

Active‐Oxygen‐Enhanced Homogeneous Nucleation of Lithium Metal on Ultrathin Layered Double Hydroxide

The development of safe lithium‐metal anodes is crucial for the next‐generation rechargeable batteries. To stabilize Li metal anodes, pre‐planting Li nucleation seeds on lithiophilic substrates is an efficient strategy to regulate initial nucleation process of Li metal. Now, activated ultrathin layered double hydroxide (U‐LDHs) are reported as a promising lithiophilic 2D material to realize the uniform deposition of Li metal. The experimental studies and DFT calculations reveal that the active oxygen on U‐LDHs provides abundant atomic‐scale active sites for Li homogeneous nucleation and plating. Moreover, the lithiophilic properties of active oxygen is also related to its coordination environments. This work opens up an opportunity to more accurate regulation and understanding of Li nucleation from atomic‐scale based on 2D ultrathin materials.     

A 3D conducting scaffold with in-situ grown lithiophilic Ni_2P nanoarrays for high stability lithium metal anodes

Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect and uncontrollable dendrite growth.Herein,we design the in-situ grown lithiophilic Ni₂P nanoarrays inside nickel foam(PNF).Uniform Ni₂P nanoarrays coating presents a very low nucleation overpotential,which induces the homogeneous Li deposition in the entire spaces of three-dimensional(3D)metal framework.Specifically,the lithiophilic Ni₂P nanoarrays possess characteristics of electrical conductivity and structural stability,which have almost no expansion and damage during repeating Li plating/stripping.Therefore,they chronically inhibit the growth of Li dendrites.This results in an outstanding Coulombic efficiency(CE)of 98% at 3 mA cm^-2 and an ultra long cycling life over 2000 cycles with a low overpotential.Consequently,the PNF-Li||LiFePO₄ battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2 C.     

ZnCo_2O_4/ZnO induced lithium deposition in multi-scaled carbon/nickel frameworks for dendrite-free lithium metal anode

Lithium metal attracts growing attention as an ideal anode candidate for next generation lithium battery systems owing to its high capacity,low density,and low working potential.However,the volume expansion of the bulk and dendrite growth on the surface of lithium anode limits its practical application.Herein,we fabricate a composite lithium host featuring both multiple scaled structure and lithiophilic property to address obstacles at both aspects of bulk and surface simultaneously.In which,the multiple scaled structure provides void space to accommodate lithium volume change while zinc and cobalt oxides sites derived from Zeolitic Imidazolate Frameworks can react with lithium and form a stable solid electrolyte interphase,leading to a stable cycling of lithium symmetrical cell for more than 500 cycles with voltage hysteresis of only 88 mV at 2 mAcm~(-2) and 5 mAh cm~(-2).Moreover,full cells paired with LiFePO_4 cathode can realize 500 cycles with 99.2%capacity retention,showing great potential for practical applications.The excellent electrochemical performance of the composite lithium anode proves the effectiveness of our anode design with multiple scaled structure and lithiophilic feature,which can be also expanded to other metal anodes for batteries.