The demand for lithium-ion batteries with high safety and high energy density is leading a research boom in solid electrolytes . Composite solid electrolytes (CSEs), which combine the advantages of inorganic solid electrolytes and polymer electrolytes , have recently been intensively investigated. Herein, a novel CSE is fabricated by incorporating Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) nanoparticles into a polystyrene-poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-polystyrene (PS-PEO-PPO-PEO-PS) pentablock copolymer matrix. The addition of LLZTO not only improves the ionic conductivity of the CSE by reducing the degree of crystallinity of PS-PEO-PPO-PEO-PS, but also provides an additional transport channel for lithium-ions. As a result, the CSE with an optimal LLZTO content of 30 wt% shows an ionic conductivity of 3.10 × 10 −4 S cm −1 (28 °C). In addition, the CSE exhibits an electrochemical stability window of 5.1 V and a lithium ion transfer number of 0.36 at 28 °C. The low interfacial impedance indicates the formation of a stable interface between the CSE and the electrodes. Thus, LiFePO 4 /Li cells prepared using the CSE deliver high discharge capacity of 151.2 mA h g −1 with capacity retention of 95.7% after 160 cycles at 0.1C. These results demonstrate the promise of the combination of block copolymer/lithium garnet composite electrolytes for practical applications in solid lithium-ion batteries.
Yingxin Zhang,Xiaohui Yu,Xiaoxiao Li,Jianguo Ren,Peng He,Chao Zhang,Cuiqing Teng,Yue-E Miao,Tianxi Liu
Flexible composite solid electrolytes (CSEs) show great potentials in high-energy all-solid-state lithium metal batteries owing to their easy fabrication, good electrochemical properties, and high safety. However, it remains challenging to achieve good interfacial compatibility between the inorganic fillers and polymer matrix, which affects the lithium-ion transport efficiency and electrochemical performances of CSEs. Herein, a dynamic crosslinked network with Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) nanoparticles as the cross-linking point is proposed for fabrication of a rapidly self-healing flexible CSE, which is signed as SHENE. The amino groups in the 3-aminopropyltriethoxysilane modified LLZTO behave as the bridge sites to react with the copolymer of 2-hydroxyethyl methacrylate- g -4-formylbenzoic acid and poly (ethylene glycol) methoxy acrylate to form imine bonds, which effectively connect the organic/inorganic interface. Compared to the traditional physical contact, the covalent imine bonds can not only enhance the interaction between the two phases, but also improve the dispersion of the ceramic LLZTO nanoparticles. Additionally, the dynamic reversibility of imine bonds allows for enhanced mechanical strength and self-repairing capabilities of SHENE. Therefore, a Li||Li symmetrical cell assembled with SHENE can stably cycle for 5000 h at 0.05 mA cm − 2 and 25 °C. The corresponding Li/SHENE/LiFePO 4 full battery also exhibits good rate performance under various C-rates. Additionally, the Li/SHENE/LFP pouch cell exhibits superior safety under various abuse conditions. Therefore, this work provides new ideas for the uniform dispersion of ceramic nanoparticles in CSEs by the facile design of forming dynamic crosslinked networks.
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