Li metal is promising as the anode for next-generation Li-ion batteries; however, uncontrollable dendrite growth and severe side reactions between the Li metal and electrolyte greatly restrict its commercialization. Here, a 3D porous protective layer constructed by core@shell-Cu@Li 3 N particles is developed to solve the above issues. This protective layer is easily prepared just by one-step dip coating in Cu(NO 3 ) 2 /N-methyl-2-pyrrolidone (NMP) solution. Due to rapid Li + transport and good wettability of the protective layer, it effectively modulates Li + flux and thus homogenizes Li deposition. More importantly, as confirmed by both the experimental results and phase-field simulations, the 3D porous protective layer enforces the Li dendrite to laterally grow to form an interconnected network, which causes that the subsequent Li deposition is constrained and filled in the inner space rather than savage growth. Therefore, both the symmetric battery and full cell constructed by the protected Li electrode displays much longer lifespan than the one with bare Li even in unstable liquid carbonate electrolyte. Also, this protective layer is demonstrated to be compatible with Li 1+x Al x Ti 2−x (PO 4 ) 3 (LATP) solid-state electrolyte by suppressing the side reactions. This work paves a new and facile strategy for developing high-performance Li metal anode.
Youlan Zou,Yanhong He,Huiyao Li,Shiyan Deng,Wenhao Tang,Shuang Deng
In order to solve the problems of low ionic conductivity, low lithium-ion transference number and weak mechanical strength of PEO solid polymer electrolytes (SPEs), this paper proposes to prepare composite cross-linked network polymer electrolytes (PEO-AAEM) through UV crosslinked polymerization of allyl acetoacetate (AAEM) and N- N -methylene diacrylamide (MBA) within the PEO SPEs. The amide group within the cross-linked network facilitates the dissociation of Li + , while the carbonyl group serves as a conduit for Li + transport. The PEO-AAEM SPEs exhibit the ionic conductivity of 5.4×10 −4 S cm −1 , with a lithium-ion transference number of 0.54 at 60 °C. The assembled Li//Li battery with proper AAEM content can be stably cycled for 2000 h at 0.2 mA cm −2 current, and LiFePO 4 //Li battery maintains a reversible capacity of 100 mA h g −1 after 500 cycles at 0.2C. This work offers a viable pathway for developing SPEs with improved electrochemical performance for all solid-state lithium metal batteries (ASSLMBs).
Liu Jie,Xu Yao,Xu Fei,Li Jing,Chen Yanbo,Qiao Junjie,Han Yuyang,Ren Yurong,Lin Bencai
In this study, zwitterionic poly(ionic liquid)-based polymer electrolytes with a network structure are prepared by ultraviolet-irradiation radical polymerization of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and zwitterionic liquids, and poly(ethylene glycol) diacrylate is used as cross-linker. The cross-linked structure endows the electrolytes with high thermal stability and excellent dimensional stability. The abundant ether-oxygen group of PEGMEA provides sufficient sites for the transport of Li + and a high ionic conductivity of 0.20 × 10 −3 S cm −1 . The electrolyte shows a high lithium-ion transference number of 0.78, owing to the excellent dissociation ability of zwitterionic liquids towards lithium salts. The lithium symmetric battery can maintain a voltage polarization of 150 mV at 0.1 mA cm −2 over 600 h. The Li/LiFePO 4 battery shows a discharge capacity of 122 mAh g −1 , a capacity retention of 90.0% after 100 cycles, and an average Coulombic efficiency exceeding 99% at 0.1 C, demonstrating strong application potential in lithium-ion batteries.
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