Unlocking solid-state conversion batteries reinforced by hierarchical microsphere stacked polymer electrolyte

• 作者: Jiulin Hu Keyi Chen Zhenguo Yao Chilin Li
• 来源期刊: 科学通报（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: ARTICLES
• 页码范围: 694-707
• 页数: 14页
• 语种: 英文

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-FeF3 conversion battery reinforced by hierarchical microsphere stacked polymer electrolyte for the first time.This g-C3N4 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 (2D)-nanosheet-built porous g-C3N4 as three-dimensional (3D) textured filler can strongly cross-link with PEO matrix and LiTFSI (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/LiFePO4 solid cells can endure an extremely high rate of 12 C.All-solid-state Li/FeF3 cells show highly stabilized capacity as high as 300 mAh/g even after 200 cycles and of～200 mAh/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 as 10-12 cm2/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-state" due to the indispensable step of polysulfide solid-liquid conversion.