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Fast, Scalable Synthesis of Micronized Ge 3 N 4 @C with a High Tap Density for Excellent Lithium Storage
Author(s) -
Kim Chanhoon,
Hwang Gaeun,
Jung JiWon,
Cho SuHo,
Cheong Jun Young,
Shin Sunghee,
Park Soojin,
Kim IlDoo
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201605975
Subject(s) - materials science , anode , micrometer , germanium , chemical engineering , lithium (medication) , nanotechnology , coating , carbon fibers , analytical chemistry (journal) , composite material , silicon , optoelectronics , electrode , composite number , chromatography , chemistry , physics , engineering , medicine , endocrinology , optics
Nanostructuring has significantly contributed to alleviating the huge volume expansion problem of the Ge anodes. However, the practical use of nanostructured Ge anodes has been hindered due to several problems including a low tap density, poor scalability, and severe side reactions. Therefore, micrometer‐sized Ge is desirable for practical use of Ge‐based anode materials. Here, micronized Ge 3 N 4 with a high tap density of 1.1 mg cm −2 has been successfully developed via a scalable wet oxidation and a subsequent nitridation process of commercially available micrometer‐sized Ge as the starting material. The micronized Ge 3 N 4 shows much‐suppressed volume expansion compared to micrometer‐sized Ge. After the carbon coating process, a thin carbon layer (≈3 nm) is uniformly coated on the micronized Ge 3 N 4 , which significantly improves electrical conductivity. As a result, micronized Ge 3 N 4 @C shows high reversible capacity of 924 mAh g −1 (2.1 mAh cm −2 ) with high mass loading of 3.5 mg cm −2 and retains 91% of initial capacity after 300 cycles at a rate of 0.5 C. Additionally, the effectiveness of Ge 3 N 4 @C as practical anodes is comprehensively demonstrated for the full cell, showing stable cycle retention and especially excellent rate capability, retaining 47% of its initial capacity at 0.2 C for 12 min discharge/charge condition.