随着智能纺织和可穿戴电子设备的迅猛发展,如何将高性能的能源存储单元柔性化、集成化,已成为纺织材料与能源科学交叉领域的前沿课题。传统的硬质液态电池难以满足织物在弯曲、折叠甚至拉伸状态下的性能需求。近日,浙江理工大学纺织科学与工程学院(国际丝绸学院)胡毅教授团队,从天然竹子的结构中汲取灵感,成功开发了一种仿生竹节结构复合固态电解质。这项创新性研究将纤维结构与电池电解质巧妙结合,为柔性可穿戴储能提供了全新的解决方案。该成果以《Biomimetic Bamboo-Node-Inspired Composite Electrolyte with Hierarchical Ion Pathways for Safe and High-Performance Solid-State Lithium Metal Batteries》为题,在国际权威期刊《Advanced Functional Materials》(影响因子19.0)上发表。论文第一作者为浙江理工大学纺织科学与工程学院(国际丝绸学院)博士研究生李德华,通讯作者为浙江理工大学博士生导师胡毅教授。
随着便携式电子设备和智能纺织品的快速发展,对兼具高安全性、高能量密度和长寿命的新型电池需求日益迫切。全固态锂金属电池(SSLMBs)因其固有的安全性和高能量密度潜力,被视为下一代电池技术的重要方向。然而,传统复合固态电解质(CSEs)因高聚合物结晶度、无机填料团聚以及不均匀的界面结构等固有缺陷,阻碍了其离子导电性的提升。为解决这些问题,浙江理工大学胡毅教授团队从天然竹子“中空通道引导、竹节强化”的分级结构中获得灵感,开发了一种仿生竹节结构复合固态电解质(PHLM-CSE)。在纺织领域,纤维和纱线是构建织物的基础,其结构直接决定了材料的性能。研究团队将这一理念迁移到电池电解质的设计中:利用静电纺丝这一纺织品制备的常用技术,将聚合物(PVDF-HFP)与无机填料(LLZTO)复合,纺制出三维多孔纳米纤维骨架。提供了优异的机械柔韧性和连续的离子传导路径。随后,通过原位自组装在纤维表面周期性地沉积ZIF-8颗粒,形成了类似“竹节”的微/纳米增强区域。这些“竹节”不仅显著提高了电解质膜的机械强度,还建立了高效的界面离子传输通道。
机理示意图:仿生竹节结构复合固态电解质(PHLM-CSE)及其分级离子传输通道的示意图。
如图1所示,SEM结果显示:纯PVDF-HFP纤维表面光滑,而掺杂LLZTO后表面出现微纳级突起(图1b),证明无机颗粒成功嵌入纤维,构成稳定“主干”骨架。经原位自组装后,ZIF-8晶体均匀分布于纤维表面,无明显团聚(图1c–d),TEM进一步验证了其均匀沉积特征(图1e–f)。氮气吸附–脱附测试表明,ZIF-8具有高比表面积(1443.5 m2/g)和分级孔结构,有利于锂离子传输(图1h)。在PEO-LiTFSI浇筑后,所得PHLM-CSE膜表面致密、无裂纹(图1g),显著优于直接浇筑的PEO膜。XRD与FTIR结果(图1i–j)进一步确认了LLZTO的嵌入和ZIF-8的成功原位生长。
Figure 1. Structural design and morphological analysis of the PHLM-CSE composite solid-state electrolyte. (a) Schematic illustration of the three-dimensional architecture of the PHLM-CSE and the proposed mechanism by which MOF facilitates Li+ transport; (b) SEM image of the PVDF-HFP/LLZTO nanofiber membrane (PHL), scale bar : 2 μm; (c) SEM image of the PHL-Zn nanofiber membrane after Zn2+ ion adsorption, scale bar: 2 μm; (d) SEM image of the PHLM nanofiber membrane following in situ MOF growth, scale bar: 1 μm; (e, f) TEM images of the PHLM nanofiber membrane highlighting internal structure; (g) SEM image of the surface morphology of the PHLM-CSE electrolyte, scale bar: 2 μm. Inset: photograph image of the as-prepared membrane; (h) Nitrogen adsorption-desorption isotherm of the as-prepared ZIF-8 measured at 77.3 K; (i) XRD patterns of the PHLM-CSE electrolyte, PHLM and PHL membranes, pristine PVDF-HFP, ZIF-8, and LLZTO. Key diffraction peaks for PVDF-HFP, LLZTO, and ZIF-8 are indicated by dotted lines and arrows for clarity; (j) Fourier transform infrared (FTIR) spectra of the PHL, ZIF-8, and PHLM nanofiber membranes.
如图2所示,PHLM-CSE因MOF引入表现出更低的Tg(-36.6 °C)和更高的Tm(58.0 °C),兼具离子迁移性与热稳定性。其断裂强度和杨氏模量显著提升,具备更优抗枝晶能力。电学性能方面,PHLM-CSE展现出更高介电常数、更强盐解离能力,在50 ℃下电导率达5.04 × 10-4 S·cm-1,并具备5.1 V的宽电化学窗口,综合性能均优于对照组。
Figure 2. Structural features and electrochemical performance of the PHLM-CSE composite electrolyte membranes. (a) Differential scanning calorimetry (DSC) curves of PHL-CSE and PHLM-CSE electrolytes, highlighting their glass transition temperature (Tg) ; (b) DSC curves of PHL-CSE and PHLM-CSE in the higher-temperature region, illustrating thermal stability; (c) Stress-strain curves of PHL-CSE, PHLM-CSE, and PEO-LiTFSI electrolytes, revealing mechanical strength and flexibility; (d) Frequency-dependent dielectric constant (εr) of PEO-LiTFSI, PHL-CSE, and PHLM-CSE electrolytes; (e) FTIR spectra of PHL, PHLM and pristine PVDF-HFP membranes, demonstrating polymer phase characteristics and structural features; (f) Arrhenius plots of ionic conductivity (σ) versus temperature for PHLM-CSE electrolytes with varying LLZO contents; (g) Comparative ionic conductivity-temperature profiles of PEO-LiTFSI, PHL-CSE, and PHLM-CSE electrolytes; (h) Bar graph comparing the lithium-ion migration activation energy (Ea) across different electrolytes; (i) Linear sweep voltammetry (LSV) curves evaluating the electrochemical stability window of the investigated membranes.
如图3所示,PHLM-CSE在50 °C下表现出快速稳定的恒压极化曲线,其锂离子迁移数高达0.64,远高于PHL-CSE(0.26)和PEO-LiTFSI(0.14)(图3a,b)。EIS结果显示其界面阻抗更低且长期稳定(图3c),交换电流密度达14.2 μA cm-2(图3d),并在0.8 mA cm-2下保持稳定电压平台(图3e),说明其具备优异的界面动力学和更高的临界电流密度,有效抑制锂枝晶生长。从电子结构上看,PVDF-HFP的低HOMO能级赋予体系良好抗氧化性,而ZIF-8与LiTFSI的低LUMO能级有助于优先形成稳定SEI(图3f)。其非均匀静电势分布(图3g)与较高结合能(图3h)进一步提升界面稳定性与Li+选择性迁移效率。
Figure 3. Electrochemical properties and interfacial stability analysis of the PHLM-CSE composite solid-state electrolyte. (a) Galvanostatic charge-discharge profiles of the PHLM-CSE-based cell, with the inset displaying the corresponding electrochemical impedance spectroscopy (EIS) data; (b) Comparison of lithium-ion transference numbers (tLi+) for PEO-LiTFSI, PHL-CSE, and PHLM-CSE electrolytes; (c) Electrochemical impedance spectra (EIS) of symmetric Li|PEO-LiTFSI|Li, Li|PHL-CSE|Li, and Li|PHLM-CSE|Li cells, reflecting interfacial resistance; (d) Linear sweep voltammetry (LSV) curves used to evaluate the electrochemical stability windows of different electrolytes; (e) Critical current density (CCD) measurements of Li|Li symmetric cells with PEO-LiTFSI, PHL-CSE, and PHLM-CSE electrolytes; (f) Molecular structures and corresponding HOMO-LUMO energy level diagrams of PVDF-HFP, PEO, LiTFSI, and ZIF-8; (g) Electrostatic potential distribution map of ZIF-8, indicating charge localization characteristics; (h) Binding energies (Eb) and optimized configurations of ZIF-8 interacting with PEO, PVDF-HFP, and their binary complex.
如图4所示,PHLM-CSE中TFSI-以解离态为主(83.3%),明显高于PHL-CSE(71.2%)和PEO-LiTFSI(20.4%)(图4a),表明MOF可削弱Li+–TFSI-作用、提升盐解离效率。MD模拟显示PHLM-CSE的Li+ MSD曲线斜率最高(图4c),RDF与CN结果(图4d,e)进一步证实其为Li+提供弱配位环境和有序扩散通道,从而显著增强迁移能力。在Li|Li对称电池中,PHLM-CSE循环稳定性超过2700圈(图4f),远优于PHL-CSE(1220圈)和PEO-LiTFSI(239圈)。XPS与EDS分析(图4h、S22)表明PHLM-CSE界面生成均匀的LiF主导SEI膜,抑制TFSI-分解并提升离子迁移效率。形貌表征(图4h–j)和原位显微观察(图4k)均显示其界面平整、无枝晶形成,进一步验证了其卓越的界面稳定性与抗枝晶能力。
Figure 4. Investigation of lithium-ion transport behavior and interfacial stability in PHLM-CSE composite solid-state electrolytes. (a) Raman spectra of PEO-LiTFSI, PHL-CSE, and PHLM-CSE composite electrolytes, highlighting variations in ion coordination environments; (b) Snapshot from a molecular dynamics (MD) simulation of the PHLM-CSE model system; (c) Mean squared displacement (MSD) curves of Li+ in PEO-LiTFSI, PHL-CSE, and PHLM-CSE electrolytes, reflecting ion mobility; (d) Radial distribution functions (RDFs) and coordination environments between Li+ and TFSI- in various electrolytes; (e) RDFs and coordination environments between Li+ and ether oxygen (–O–) atoms in the EO segments; (f) Galvanostatic cycling performance of Li|Li symmetric cells with PHLM-CSE, PHL-CSE, and PEO-LiTFSI electrolytes at 0.1 mA cm-2. (g) enlarged voltage profiles near the short-circuit or failure points in Li|PEO-LiTFSI|Li, Li|PHLM-CSE|Li, and Li|PHL-CSE|Li cell; (h) F 1s core-level XPS spectra of Li anodes after 100 cycles with different electrolytes; (i) SEM images of Li metal surfaces after cycling; (j) Two-dimensional laser confocal microscopy imagesshowing cycled surface morphology; (k) Three-dimensional laser confocal microscopy reconstructions of Li metal surfaces following long-term cycling.
如图5所示,LiFePO?|PHLM-CSE|Li电池在0.2–2 C下保持高比容量(144.2→83.3 mAh g-1),倍率恢复良好(图5a,b),循环200圈后容量保持率达97.2%(图5c),在1 C下可稳定运行600圈以上。进一步在NCM811体系中,PHLM-CSE电池在1 C下循环800圈后仍保持95.2%容量(图5e,f),显著优于PHL-CSE和PEO体系,且表现出宽温适应性(20–60 °C)。这种优势源于MOF促进盐解离与Li+迁移,以及LLZTO增强界面稳定性和力学强度。在应用方面,基于PHLM-CSE的柔性软包电池在弯折、折叠、穿刺及火焰暴露下仍能稳定驱动LED(图5g),并在集成至肌电传感器与智能终端中表现出稳定供电(图5h,i)。其在0.2 C下容量约170 mAh g-1,库仑效率>99%,兼具高能量密度、安全性和柔性,展示了在可穿戴能源系统中的广阔应用前景。
Figure 5. Electrochemical performance and flexible applications of PHLM-CSE-based solid-state lithium metal batteries. (a) Rate capability and (b) corresponding charge–discharge profiles of LiFePO4|PHLM-CSE|Li full cells at various current densities. (c) Long-term cycling performance at 0.2 C and (d) corresponding voltage profiles. (e) Cycling stability of NCM811|PHLM-CSE|Li, NCM811|PHL-CSE|Li, and NCM811|PEO-LiTFSI|Li full cells at 1 C, and (f) their voltage profiles. (g) Optical images showing stable operation of a pouch cell under flat, folded, cut, and punctured conditions. (h,i) Demonstration of the pouch cell powering an electromyography (EMG) sensor and a smartphone, respectively.
总之,本研究受竹节结构启发,构建了仿生复合固态电解质(PHLM-CSE)。通过静电纺丝与原位ZIF-8组装形成连续离子通道和稳固网络,显著提升了离子传输与力学强度。PHLM-CSE在50 °C下具备高离子导电率(5.0 × 10-4 S·cm-1)、高迁移数(0.64)、宽电化学窗口(5.1 V)和优异力学性能。电池测试显示其兼具长寿命(对称电池>3400 h)、高稳定性(NCM811全电池800圈保持率95.2%)及柔性应用潜力,为实现高性能、本征稳定的固态锂金属电池提供了新思路。
在此,感谢浙江省自然科学基金项目(LY21E030023)和浙江理工大学嵊州创新研究院基金项目(SYY2024C000008)的支持!
通讯作者简介:胡毅,男,博士,教授,博士生导师。浙江理工大学纺织科学与工程学院(国际丝绸学院)副院长,主要从事非水介质染整新技术和柔性电子智能纺织品研究。以第一作者或通讯作者在Advanced Functional Materials, Energy Storage Materials,Advanced Fiber Materials, Nano Letters, Nano Energy等刊物上发表SCI论文70余篇,授权和转化国家发明专利30余项。获得国家级教学成果二等奖和浙江省教学成果特等奖各1项;主持获得中国纺织工业联合会教学成果一、二、三等奖,浙江省自然科学奖三等奖和中国商业联合会科技进步奖二等奖各1项。
原文链接:https://doi.org/10.1002/adfm.202514738
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