Fast, Scalable Synthesis of Micronized Ge₃N₄@C with a High Tap Density for Excellent Lithium Storage

Abstract

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 Ge3N4 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 Ge3N4 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 Ge3N4, which significantly improves electrical conductivity. As a result, micronized Ge3N4@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 Ge3N4@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.

Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide

“…The decreases in specific capacity after 150 charge–discharge cycles compared to the second cycle were 44% (from 1404 to 785 mAh g −1 ), 66% (from 1696 to 575 mAh g −1 ), and 58% (from 990 to 408 mAh g −1 ) for the GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80 anodes, respectively. The obtained results were not inferior to the recently reported data for GeO 2 [ 23 , 24 , 50 ], Ge 3 N 4 [ 43 , 45 ], and GeP anodes [ 35 ]. This can be attributed to the large volume expansion of the inorganic phase.…”

“…The galvanostatic charge–discharge curves of the three different germanium compounds are presented in Figure 3 d–f. The first and second cycles at 100 mA g −1 showed good first cycle efficiency of about 68, 80, and 63% for GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80, respectively, which were not inferior and mostly exceeded the best-published values, including those tested at a narrower potential window of up to 1.5 V [ 33 , 43 , 45 , 50 ].…”

Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide

“…The decreases in specific capacity after 150 charge–discharge cycles compared to the second cycle were 44% (from 1404 to 785 mAh g −1 ), 66% (from 1696 to 575 mAh g −1 ), and 58% (from 990 to 408 mAh g −1 ) for the GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80 anodes, respectively. The obtained results were not inferior to the recently reported data for GeO 2 [ 23 , 24 , 50 ], Ge 3 N 4 [ 43 , 45 ], and GeP anodes [ 35 ]. This can be attributed to the large volume expansion of the inorganic phase.…”

“…The galvanostatic charge–discharge curves of the three different germanium compounds are presented in Figure 3 d–f. The first and second cycles at 100 mA g −1 showed good first cycle efficiency of about 68, 80, and 63% for GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80, respectively, which were not inferior and mostly exceeded the best-published values, including those tested at a narrower potential window of up to 1.5 V [ 33 , 43 , 45 , 50 ].…”

In-situ construction of conducting alloy interphase towards modulating Li-ion storage kinetics

“…S6(a-d), compared with pure MoS 2 , MCMB and conductive carbon black (Super-P), the Ge@MoGe 2 @MoS 2 composite shows a higher tap density (1.23 g cm À3 ). This high tap density of the Ge@MoGe 2 @MoS 2 anodes are superior to most other previously reported Ge-based anode materials, as listed in Table S2 [18,32,44,59]. The particle size of Ge@MoGe 2 @MoS 2 (Fig.…”

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

“…The semicircle appearing in the highfrequency region is assigned to the contact resistance by the formation of an SEI layer (R SEI ) and the medium-frequency semicircle is attributed to the charge transfer resistance (R ct ). 27 The straight line in the low-frequency region indicates the mass transfer of Li ions. 26 Owing to the enhanced electrical conductivity of lithiated negative electrodes, higher R SEI than R ct was shown in both samples.…”

Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide

“…The decreases in specific capacity after 150 charge–discharge cycles compared to the second cycle were 44% (from 1404 to 785 mAh g −1 ), 66% (from 1696 to 575 mAh g −1 ), and 58% (from 990 to 408 mAh g −1 ) for the GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80 anodes, respectively. The obtained results were not inferior to the recently reported data for GeO 2 [ 23 , 24 , 50 ], Ge 3 N 4 [ 43 , 45 ], and GeP anodes [ 35 ]. This can be attributed to the large volume expansion of the inorganic phase.…”

“…The galvanostatic charge–discharge curves of the three different germanium compounds are presented in Figure 3 d–f. The first and second cycles at 100 mA g −1 showed good first cycle efficiency of about 68, 80, and 63% for GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80, respectively, which were not inferior and mostly exceeded the best-published values, including those tested at a narrower potential window of up to 1.5 V [ 33 , 43 , 45 , 50 ].…”

In-situ construction of conducting alloy interphase towards modulating Li-ion storage kinetics

“…S6(a-d), compared with pure MoS 2 , MCMB and conductive carbon black (Super-P), the Ge@MoGe 2 @MoS 2 composite shows a higher tap density (1.23 g cm À3 ). This high tap density of the Ge@MoGe 2 @MoS 2 anodes are superior to most other previously reported Ge-based anode materials, as listed in Table S2 [18,32,44,59]. The particle size of Ge@MoGe 2 @MoS 2 (Fig.…”

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

“…The semicircle appearing in the highfrequency region is assigned to the contact resistance by the formation of an SEI layer (R SEI ) and the medium-frequency semicircle is attributed to the charge transfer resistance (R ct ). 27 The straight line in the low-frequency region indicates the mass transfer of Li ions. 26 Owing to the enhanced electrical conductivity of lithiated negative electrodes, higher R SEI than R ct was shown in both samples.…”

Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide

“…The decreases in specific capacity after 150 charge–discharge cycles compared to the second cycle were 44% (from 1404 to 785 mAh g −1 ), 66% (from 1696 to 575 mAh g −1 ), and 58% (from 990 to 408 mAh g −1 ) for the GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80 anodes, respectively. The obtained results were not inferior to the recently reported data for GeO 2 [ 23 , 24 , 50 ], Ge 3 N 4 [ 43 , 45 ], and GeP anodes [ 35 ]. This can be attributed to the large volume expansion of the inorganic phase.…”

“…The galvanostatic charge–discharge curves of the three different germanium compounds are presented in Figure 3 d–f. The first and second cycles at 100 mA g −1 showed good first cycle efficiency of about 68, 80, and 63% for GeO 2 -rGO-80, Ge 3 N 4 -rGO-80, and GeP-rGO-80, respectively, which were not inferior and mostly exceeded the best-published values, including those tested at a narrower potential window of up to 1.5 V [ 33 , 43 , 45 , 50 ].…”

In-situ construction of conducting alloy interphase towards modulating Li-ion storage kinetics

“…S6(a-d), compared with pure MoS 2 , MCMB and conductive carbon black (Super-P), the Ge@MoGe 2 @MoS 2 composite shows a higher tap density (1.23 g cm À3 ). This high tap density of the Ge@MoGe 2 @MoS 2 anodes are superior to most other previously reported Ge-based anode materials, as listed in Table S2 [18,32,44,59]. The particle size of Ge@MoGe 2 @MoS 2 (Fig.…”

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

“…The semicircle appearing in the highfrequency region is assigned to the contact resistance by the formation of an SEI layer (R SEI ) and the medium-frequency semicircle is attributed to the charge transfer resistance (R ct ). 27 The straight line in the low-frequency region indicates the mass transfer of Li ions. 26 Owing to the enhanced electrical conductivity of lithiated negative electrodes, higher R SEI than R ct was shown in both samples.…”