Jie Liu,Yufeng Cao,Jinqiu Zhou,Mengfan Wang,Hongli Chen,Tingzhou Yang,Yawen Sun,Tao Qian,Chenglin Yan
The persistent reduction reactions between the hyperactive lithium metal (Li) and dissolved polysulfides would passivate the Li metal and rapidly decrease the cathodic active materials, thus leading to low Coulombic efficiency and a short cycle life of lithium–sulfur (Li–S) batteries. Herein, we construct artificial lithium isopropyl-sulfide macromolecules as an ion-selective interface on the Li metal (IS-Li) by a facile electrochemical polymerization method, in which the polymer network improves the elasticity and toughness to accommodate the volume change of the Li anode and the formed lithium-organosulfides provide great mechanical strength to resist the destruction of Li dendrites. Importantly, this interfacial layer is proved to be sufficient in damping polysulfide anion diffusion and stopping irreversible reduction between polysulfides and metallic Li, which greatly contribute to the performance improvement of Li–S batteries. The resulting Li–S batteries exhibit long-term stability with high capacity retention and Coulombic efficiency. This effective strategy sets a new approach for regulating the interfacial chemistry of Li metal anodes, which is significant for highly stable Li–S batteries.
Haojing Liu,Hongkai Hu,Weiya Li,Kang Dong,Zehao Shi,Chengliang Lin,Xiang Huang,Linglong Kong,Yongcheng Jin
The advancement of lithium metal batteries is critically limited by the inherent constraints of liquid electrolytes in terms of energy density and safety, driving the pursuit of high-performance solid polymer electrolytes. Herein, a composite polymer electrolyte based on poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) matrix and two-dimensional (2D) layered vermiculite nanosheets (VS) fillers is proposed. PVDF-HFP could integrate into the interlayer spaces of VS, and build the chemical bond to create an active interface for rapid Li + transport. The negatively charged surface and high cation exchange capacity of VS augment the amount of free Li + , and endow the PVDF-HFP/VS composite electrolyte with high ionic conductivity (0.42 mS cm −1 ), large Li + transference number (0.45) at room temperature, and an expanded electrochemical window (∼5.2 V). Consequently, the corresponding Li|LiMn 0.6 Fe 0.4 PO 4 (LMFP) solid-state battery achieves a high capacity of 101.3 mAh g −1 at 5C, and the Li|LiFePO 4 (LFP) solid-state battery maintains a reversible capacity of 122 mAh g −1 even after 500 cycles at 1C, which further highlights the active role of 2D clay nanomaterials in constituting high-performance polymer electrolyte for solid-state Li battery.
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