The Li-Mg-N-H hydrogen storage system is a promising hydrogen storage material due to its moderate operation temperature,good reversibility,and relatively high capacity.In this work,the Li-Mg-N-H composite was directly synthesized by reactive ball milling(RBM)of Li3N and Mg powder mixture with a molar ratio of 2:1 under hydrogen pressure of 9 MPa.More than 8.8 wt％hydrogen was absorbed during the RBM process.The phases and structural evolution during the in situ hydro-genation process were analyzed by means of in situ solid-gas absorption and ex situ X-ray diffraction(XRD)mea-surements.It is determined that the hydrogenation can be divided into two steps,leading to mainly the formation of a lithium magnesium imide phase and a poorly crystallized amide phase,respectively.The H-cycling properties of the as-milled composite were determined by temperature-pro-grammed dehydrogenation(TPD)method in a closed sys-tem.The onset dehydrogenation temperature was detected at 125℃,and it can reversibly desorb 3.1 wt％hydrogen under a hydrogen back pressure of 0.2 MPa.The structural evolution during dehydrogenation was further investigated by in situ XRD measurement.It is found that Mg(NH2)2 phase disappears at about 200℃,and Li2Mg2N3H3,LiNH2,and Li2MgN2H2 phases coexist at even 300℃,revealing that the dehydrogenation process is step-wised and only partial hydrogen can be desorbed.

Zhi-Nian Li;Hao-Chen Qiu;Shu-Mao Wang;Li-Jun Jiang;Jun Du;Jun-Xian Zhang;Michel Latroche;Fermin Cuevas

Department of Energy Materials and Technology,General Research Institute for Nonferrous Metals,Beijing 100088,China;UMR7182,CMTR/ICMPE/CNRS-UPEC,94320 Thiais Cedex,France

稀有金属（英文版）

[1]Zhi-Nian Li;Hao-Chen Qiu;Shu-Mao Wang;Li-Jun Jiang;Jun Du;Jun-Xian Zhang;Michel Latroche;Fermin Cuevas-.Mechanochemistry and hydrogen storage properties of 2Li3N+Mg mixture)[J].稀有金属（英文版）,2022(12):4223-4229

Mechanochemistry,2Li3N+Mg,Li2Mg2N3H3,LiNH2,Li2MgN2H2,wised

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