Low ionic conductivity and large interfacial impedance between the electrode and electrolyte are the main bottleneck issues of the current solid electrolytes . In this study, a novel 3D hierarchical solid electrolyte was developed to tackle the large interfacial impedance problem. A flexible polyethylene oxide/lithium chlorate (PEO/LiClO 4 ) was in-situ formed inside the 3D porous Li 6.28 La 3 Zr 2 Al 0.24 O 12 (LLZAO) network by simply using a cleanroom wiper as the template. The obtained 3D LLZAO-PEO/LiClO 4 composite solid electrolyte exhibited a high ionic conductivity of 2.25 × 10 −5 S cm −1 at 30 °C, being 30.7 times higher than that of pristine PEO/LiClO 4 electrolyte. The improved ionic conductivity was attributed to the 3D porous LLZAO structure with continuous fast ion transport pathways. In addition, the 3D LLZAO network can effectively inhibited the growth of lithium dendrite , leading to excellent stability and desirable safety during lithium stripping/plating cycling. Furthermore, the all-solid-state LiFePO 4 /Li battery system based on the obtained 3D LLZAO-PEO/LiClO 4 electrolyte showed a high initial discharge specific capacity of 143.8 mAh·g −1 and a high capacity retention of 86% after 200 cycles at 60 °C. This 3D composite solid electrolyte design is very effective in reducing the interfacial impedance and provides a solution for the further development of high-performance solid electrolyte for all-solid-state rechargeable batteries.
All-solid-state batteries are proposed to have ultimate safety and higher power and energy densities over conventional lithium ion batteries with liquid electrolytes . The Li ion conductivity and interfacial resistance between electrolyte and electrodes are the major bottleneck of the development of all-solid-state batteries for practical uses. Here, we reported a novel composite electrolyte which is composed of uniform distributed Li ion conducting Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) fillers in PEO/LiClO 4 matrix. The EO:Li + ratio of 15:1 is being used to achieve lower interfacial resistance between electrolyte and electrodes through the melting process. The composite electrolyte is fabricated by simple solution casting method, which is more advantageous comparing with high temperature sintering or sol-gel method used in the fabrication of ceramic electrolytes. The composite electrolyte exhibits good Li ion conductivity of 4.8 × 10 −4 Scm −1 at 60 °C and excellent interfacial stability against Li metal. The all-solid-state lithium battery using this composite electrolyte shows a specific capacity of 140mAhg −1 and an unprecedentedly high capacity retention of 83% after 500 cycles at 60 °C and the rate of 1C. It is concluded that good electrode/electrolyte interfacial stability and contact as well as fast Li ion conductivity obtained by the addition of active garnet particulates to PEO/LiClO 4 matrix are essential criteria for good charge/discharge performance of all-solid-state lithium batteries.
Ruyan Lei,Yanping Yang,Chenjuan Yu,Yinsi Xu,Yuanzhuo Li,Jun Li
In order to improve the electrochemical performance and efficiently prepare a solid polymer electrolyte (SPE) for the lithium-metal battery (LMB), a fumed SiO2 (FS) with surface Si–OH group was used to fabricate FS-modified poly(ethylene oxide) (PEO)–LiClO4-based SPE by a facile preparation process. The influences of the FS content on the morphological properties, thermal properties, lithium salt dissociation, mechanical properties, and electrochemical properties of SPE were systematically analyzed. Results indicate that FS with the hydrophilic property was widely distributed throughout the amorphous phase of SPE, thus the crystallinity of SPE was reduced to 25.83% when the FS mass loading was 6.85 wt%. In addition, a greater dissociation degree of lithium salt was achieved after the addition of FS, and a higher ion conductivity of 3.03 × 10−4 S cm−1 and Li-ion migration number of 0.396 were recorded at 60 °C. The all-solid-state Li/SPE/Li coin cell showed excellent stable cyclability (380 h) and the LiFePO4 (LFP)/SPE/Li coin cell demonstrated good discharge specific capacity and coulomb efficiency of 96 mA h g−1 and 100.2%, respectively, after 100 cycles of galvanostatic charge–discharge operation under 0.5C at 60 °C. Thus, based on collective results, it is expected that SPE presented in this work is a promising electrolyte for next-generation high-energy all-solid-state LMB with enhanced safety.
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