Li metal anodes, which possess ultrahigh theoretical capacity, are considered the ultimate solution for high energy density batteries. However, issues regarding safety and rapid electrode degradation due to Li dendrite growth have restricted the commercialization of Li metal anodes for several decades. Herein, a stable, dendrite-free Li metal anode with a hairy-layered architecture is reported, which is realized though a facile electrochemical deposition of Li on a lithiophilic LTO/Ti3C2 composite. The simultaneous formation of the lithiophilic composite could induce the uniform deposition of Li ions and acted as an interlayer skeleton for the intercalation of Li ions. A microscale uniform electric field could also be formed to regulate the Li-ion deposition behaviour. Thus, the growth of dendrites could be inhibited, the formation of dead Li could be prevented, and a stable, long-life Li metal anode could be realized. The obtained Li/LTO/Ti3C2/Cu electrode could reversibly charge/discharge for 2000 h with a high current of 1 mA cm−2 and an ultralow voltage hysteresis of 20 mV. Full batteries with the Li/LTO/Ti3C2/Cu anode exhibit excellent electrochemical performance. This work provides a promising anode design strategy for the fabrication of high-performance and safe Li metal batteries.
Polyethylene oxide (PEO) based solid-state electrolytes are known for the low manufacturing cost and excellent processability, but their practical application is paved with thorns including the inferior ionic conductivity, low Li + transfer number and insufficient Li dendrite blocking ability. Herein, we propose organic montmorillonite (OMMT) with expanded layer spacing (1.97 nm) as versatile fillers to construct PEO-OMMT electrolyte, in which OMMT not only increases Li + transfer number (0.56) and ionic conductivity (7.15 × 10 −4 S cm −1 ), providing fast ionic transport channels, but also endows PEO with high mechanical strength, resulting remarkable Li dendrite blocking ability (>2100 h). Additionally, the high dielectric constant and Lewis-rich polar sites of OMMT facilitate the dissociation of lithium salts and the rapid formation of LiF and Li 3 N-rich solid electrolyte interface layers. Impressively, the LiFePO 4 | PEO-OMMT | Li cell shows a high initial capacity (154.4 mAh g −1 at 0.5C) with ultralong cycling lifespan (>1200 cycles). Similarly, the LiNi 0.83 Mn 0.05 Co 0.12 O 2 | PEO-OMMT | Li cell retains a high discharge capacity of 151.5 mAh g −1 after 100 cycles at 0.2C. This work highlights the indelible contributions of OMMT functionalized fillers in improving the interfacial stability of PEO based solid-state electrolytes, paving a feasible avenue for the practical application of solid-state lithium metal batteries.
Xingyi Shi,Qingwei Sun,Bismark Boateng,Yinghua Niu,Yidong Han,Weiqiang Lv,Weidong He
The safety of lithium ion batteries is correlated closely to the mechanical property and thermal stability of separators. The polymer/ceramic particle composite separators are widely investigated for quasi-solid gel separators of lithium ion batteries, but the nonuniform dispersion of ceramic particles limits their performance. In this study, ball-milled Al-doped Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 suspension is incorporated into poly (vinylidene fluoride- co -hexafluoropropylene) gel to prepare a highly uniform quasi-solid composite separator. The results show that adding only 4.29 wt% Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 into PVDF-HFP increases ductility by three times and the mechanical strength by 38% as compared with pure PVDF-HFP separator. Batteries with the composite separator show significantly improved cyclic stability and rate performance at both room temperature and temperatures up to 80 °C. In particular, the composite separator promotes homogenous Li + flux through the separator and suppresses Li dendrite growth in Li-metal based batteries.
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