摘要
锂金属电池(LMBs)因其高理论比容量(3860 mAh·g^(-1))和低还原电位(-3.04 V vs.SHE),被认为是实现下一代高性能储能设备的候选者。然而,由于锂金属负极具有枝晶隐患,且传统液态电解质存在化学稳定性差、易燃等安全问题,严重影响了电池的寿命和安全,阻碍了其商业化进程。为解决上述问题,采用简单的室温合成方法成功制备了富含活性位点的共价有机框架(COF-SH),通过溶液浇铸工艺将聚氧化乙烯(PEO)和COF-SH结合制备PEO@COF-SH聚合物固态电解质薄膜并将其应用于锂金属电池的电解质材料中。研究结果表明,COF-SH中丰富的活性位点可以调控COF结构的局部电化学环境,有效促进双三氟甲磺酰亚胺锂(LiTFSI)的解离,并加快Li^(+)在COF-SH有序的一维孔道结构中运输,从而促进了体系的动力学反应。强吸电子基可以调节共价有机骨架的电子结构,构建特定的阳离子导向通道。在这种高选择性的Li^(+)运输通道和调节的表面电荷下,实现了Li^(+)的均匀沉积和Li枝晶的抑制,提高阳极和电解质界面的稳定性。有序的纳米通道、丰富的活性位点可以促使离子的快速迁移,显著提升离子电导率,从而实现稳定的锂沉积和剥离。因此COF-SH电解质薄膜在60℃表现出0.81的高锂离子迁移数和4.0×10^(-4) S·cm^(-1)的离子电导率。Li/PEO@COF-SH/Li对称电池在0.1 mA·cm^(-2)的电流密度和0.1 mAh·cm^(-2)的面容量下稳定循环1500 h并保持16 mV的过电位,在0.2 mA·cm^(-2)的电流密度和0.2 mAh·cm^(-2)的面容量下稳定循环1000 h,过电位为34 mV。LiFePO_(4)/PEO@COF-SH/Li在1 C倍率下表现出154.3 mAh·g^(-1)的初始比容量,经过300次循环后依然有137.0 mAh·g^(-1)的可逆比容量,容量保持率为88.7%,循环容量衰减率每次循环仅为0.04%,表现出优异的循环稳定性。研究成果为设计柔性高离子电导率的PEO基固态电解质薄膜提供了重要的理论指导与实践参考。
Lithium metal batteries(LMBs),with high theoretical specific capacity of 3860 mAh·g^(-1)and extremely low reduction potential(−3.04 V vs.SHE),are considered promising candidates for next-generation high-performance energy storage.However,their commercialization is limited by challenges such as the risk of lithium metal dendrite formation on the anode and the poor chemical stability and flammability of conventional liquid electrolytes,which adversely affect both battery lifespan and safety.This work successfully synthesized covalent organic framework(COF-SH)rich in active sites using a simple room-temperature synthesis method.A PEO@COF-SH polymer solid-state electrolyte film was then prepared by combining poly(ethylene oxide)(PEO)with COF-SH through a solution casting process,and applied as the electrolyte material in lithium metal batteries.The results show that the active sites in COF-SH can modulate the local electrochemical environment,effectively promote the dissociation of Lithium bis(trifluoromethanesulfonyl)imide(LiTFSI),and accelerate Li^(+)transport through the ordered one-dimensional channels in COF-SH,thereby enhancing system kinetics.Electron-withdrawing groups can modulate the electronic structure of the covalent organic framework,creating specific cation-guided channels.Under this highly selective Li^(+)transport channel and the adjusted surface charge,uniform Li^(+)deposition and suppression of lithium dendrites are achieved,improving the stability of the anode-electrolyte interface.The ordered nanopores and abundant active sites facilitate rapid ion migration,significantly enhancing ionic conductivity,thereby enabling stable lithium deposition and stripping.As a result,the COF-SH electrolyte film demonstrated a high lithium-ion transference number of 0.81 at 60℃ and a conductivity of 4.0×10^(-4) S·cm^(-1).The Li/PEO@COF-SH/Li symmetric cell exhibits stable cycling for 1500 h at a current density of 0.1 mA·cm^(-2)and areal capacity of 0.1 mAh·cm^(-2) with a low overpotential of 16 mV.The same cell also showed stable cycling for 1000 h at a current density of 0.2 mA·cm^(-2) and areal capacity of 0.2 mAh·cm^(-2),with an overpotential of 34 mV.The LiFePO_(4)/PEO@COF-SH/Li cell exhibited an initial specific capacity of 154.3 mAh·g^(-1) at a 1 C,retaining 137.0 mAh·g^(-1) after 300 cycles with a capacity retention of 88.7%.The cycle capacity decay rate was only 0.04%per cycle,demonstrating excellent cycling stability.These findings offer important theoretical guidance and practical reference for the design of flexible,high ionic conductivity PEO-based solid-state electrolyte films.
作者
梁伟荃
吴家怡
吴昊
廖春烨
钱艳楠
李运勇
LIANG Weiquan;WU Jiayi;WU Hao;LIAO Chunye;QIAN Yannan;LI Yunyong(School of Materials and Energy,Guangdong University of Technology,Guangzhou 510006,China)
出处
《材料研究与应用》
2026年第3期280-289,共10页
Materials Research and Application
基金
中国广东省自然科学基金资助项目(2024A1515012499)
国家自然科学基金资助项目(51972066)。
关键词
锂金属电池
锂枝晶
PEO基固态电解质
共价有机框架
亲锂位点
强吸电子基
溶液浇铸
均匀锂沉积
lithium metal battery
lithium dendrites
PEO-based solid-state electrolyte
covalent organic framework
lithiumaffinity sites
strong electron-withdrawing groups
solution casting
uniform lithium deposition
