The electrode–electrolyte interface stability is a critical factor influencing cycle performance of All-solid-state lithium batteries (ASSLBs). Here, we propose a LiF- and Li3N-enriched artificial solid state electrolyte interphase (SEI) protective layer on metallic lithium (Li). The SEI layer can stabilize metallic Li anode and improve the interface compatibility at the Li anode side in ASSLBs. We also developed a Li1.5Al0.5Ge1.5(PO4)3–poly­(ethylene oxide) (LAGP-PEO) concrete structured composite solid electrolyte. The symmetric Li/LAGP-PEO/Li cells with SEI-protected Li anodes have been stably cycled with small polarization at a current density of 0.05 mA cm–2 at 50 °C for nearly 400 h. ASSLB-based on SEI-protected Li anode, LAGP-PEO electrolyte, and LiFePO4 (LFP) cathode exhibits excellent cyclic stability with an initial discharge capacity of 147.2 mA h g–1 and a retention of 96% after 200 cycles.

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with natural abundance and low discharge potential, it has been considered as one of the most promising candidate as next generation anode materials for LIBs. [5] However, Si anode have fast failure problems of structure degradation, unsatisfactory coulombic efficiency (CE), and rapid capacity fading due to the large volume variation (≈300%) and unstable solid-electrolyte interphase (SEI) during alloying/dealloying process. With the fundamental understanding of failure mechanisms of Si anode, different approaches have been investigated by researchers. 1) Building various Si nanostructures to solve the volume expansion problem. [6][7][8][9][10][11][12][13][14] 2) Developing different coating strategy to enhance its structural stability and reducing SEI formation. [15][16][17][18] 3) Using additives in the electrolyte to stabilize the SEI. [19,20] However, the cycling performance of Si anode still needs to be improved. The capacity decay of Si anode is generally ascribed to a combination of volume variation and SEI formation, and there are also evidences indicating that lithium trapping is also one of the important factors to affect the electrochemical performance of Si electrodes. [21][22][23] The lithium trapping causes capacity decay due to incomplete delithiation of Si during high rate cycling, leading to capacity decay and unsatisfactory columbic efficiency. Despite all these above, lithium trapping has received relatively little attention so far, and it requires further investigation.Here, we have designed a new Si@LiAlO 2 structure by synthesizing LiAlO 2 thin coating on Si nanoparticles. The LiAlO 2 coating serves as an artificial SEI film with better lithium-ion diffusivity than naturally formed SEI layer, which enhances the rate performance and reduces the lithium trapping. By carrying out in situ Raman measurements on the LiAlO 2 coated Si anode, we have investigated the alloying process of Si during lithiation and confirmed LiAlO 2 can enhance the alloying process during lithiation. Owing to the LiAlO 2 coating, the Si anode demonstrates a superior electrochemical performance, which presents a specific capacity of 2013 mAh g −1 at a current density of 1000 mAh g −1 and 1106 mAh g −1 at a current density of 4000 mA g −1 with a capacity retention of 90.9% after 500 cycles.The investigation indicates that lithium trapping in Si anode of lithiumion battery is one of the key factors to affect the coulombic efficiency and capacity decay during high rate cycling. Here, it is demonstrated that LiAlO 2 as an artificial solid electrolyte interphase (SEI) on commercial Si nanoparticles can effectively address the lithium trapping issues of Si anode to improve its electrochemical performance. By investigating the structure evolution of Si with in situ Raman and ex situ X-ray diffraction measurements, it is demonstrated that artificial solid electrolyte interphase layer significantly improves the kinetics of lithium alloying/dealloying process due to its better electrochemical performance comparing to the natural SE...

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A novel flexible P/carbon nanofibers@graphene electrode, which exhibits an excellent electrochemical performance, is fabricated via a vapor-redistribution and electrospinning method.