摘要
Pursuing all-solid-state lithium metal batteries with dual upgrading of safety and energy density is of great significance. However, searching compatible solid electrolyte and reversible conversion cathode is still a big challenge. The phase transformation at cathode and Li deformation at anode would usually deactivate the electrode-electrolyte interfaces. Herein, we propose an all-solid-state Li-FeF_(3) conversion battery reinforced by hierarchical microsphere stacked polymer electrolyte for the first time. This gC_(3)N_(4) stuffed polyethylene oxide(PEO)-based electrolyte is lightweight due to the absence of metal element doping, and it enables the spatial confinement and dissolution suppression of conversion products at soft cathode-polymer interface, as well as Li dendrite inhibition at filler-reinforced anode-polymer interface. Two-dimensional(2 D)-nanosheet-built porous g-C_(3)N_(4) as three-dimensional(3 D) textured filler can strongly cross-link with PEO matrix and Li TFSI(TFSI: bistrifluoromethanesulfonimide) anion, leading to a more conductive and salt-dissociated interface and therefore improved conductivity(2.5×10^(-4) S/cm at 60℃) and Li+transference number(0.69). The compact stacking of highly regular robust microspheres in polymer electrolyte enables a successful stabilization and smoothening of Li metal with ultra-long plating/striping cycling for at least 10,000 h. The corresponding Li/LiFePO_(4) solid cells can endure an extremely high rate of 12 C. All-solid-state Li/FeF_(3) cells show highly stabilized capacity as high as 300 m Ah/g even after 200 cycles and of 200 m Ah/g at extremely high rate of 5 C, as well as ultra-long cycling for at least 1200 cycles at 1 C. High pseudocapacitance contribution(>55%) and diffusion coefficient(as high as10^(-12) cm^(2)/s) are responsible for this high-rate fluoride conversion. This result provides a promising solution to conversion-type Li metal batteries of high energy and safety beyond Li-S batteries, which are difficult to realize true "all-solid-sta
开发能量密度和安全性双重升级的固态锂金属电池具有重要意义.由金属锂匹配廉价的FeF_(3)正极构建的转换反应型锂氟电池的能量密度有望突破500 Wh/kg,但是面临着正极侧电化学可逆性和负极侧锂形貌稳定性的双重挑战.在本工作中,我们率先开发出一种聚合增强型的锂氟转换全固态电池,利用分级多孔的碳氮聚合物微球堆叠强化的复合电解质,不仅可以在正极的"软接触"界面处实现转换反应产物的空间限域和溶解抑制效应,还可以在负极侧有效地抑制锂枝晶生长.由二维纳米片自组装构建的三维多孔g-C_(3)N_(4)织构填充物可与聚氧化乙烯(PEO)基质和锂盐(Li TFSI)中阴离子均发生强烈的交联作用,实现了离子电导率(60℃时为2.5×10^(-4)S/cm)和锂离子迁移数(0.69)的提高.锂金属对称电池能够稳定实现锂沉积/剥离循环至少10,000 h.全固态Li/FeF_(3)电池显示出可高度稳定的容量,即使在5 C的高倍率下,可逆容量依旧维持在200 m Ah/g, 1 C倍率下可至少进行1200次的超长循环.
作者
Jiulin Hu
Keyi Chen
Zhenguo Yao
Chilin Li
胡九林;陈克艺;姚振国;李驰麟(State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 201899,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)
基金
supported by the National Key R&D Program of China (2016YFB0901600),NSAF (U1830113)
the National Natural Science Foundation of China (51772313 and 21975276)
Shanghai Science and Technology Committee (20520710800)。
