Hierarchical N-doping germanium/carbon nanofibers as anode for high-performance lithium-ion and sodium-ion batteries

Abstract

Germanium (Ge) has gained a great deal of attention as an anode material for sodium ion batteries (SIBs) and lithium ion batteries (LIBs) for its high theoretical capacity and ion diffusivity. Unfortunately, Ge particle pulverization triggered by huge volume expansion during the alloying and dealloying processes can cause rapid capacity fade. Herein we report a facile method for the preparation of ultrafine Ge nanoparticles embedded in hierarchical N-doped multichannel carbon fibers (denoted as Ge-NMCFs) by electrospinning. The hierarchical carbon matrix not only provides sufficient internal void space to accommodate the large volume expansion of Ge nanoparticles, but also provides numerous open channels for the easy access of electrolyte and Na/Li ions. As half-cell tests revealed, the composite provides discharge capacity of 303 mA h g −1 (1st cycle) and 160 mA h g −1 (700th cycle) for SIBs, 1146.7 mA h g −1 (1st cycle) and 600 mA h g −1 (500th cycle) for LIBs at a current density of 500 mA g −1 (all the presented capacity based on the total weight of Ge/C composites). Density functional theory calculation suggests that N-doped in carbon can enhance the Na/Li ion storage and improve the electrochemical performance. This demonstration is an important step towards the development of SIBs and LIBs with much higher specific energy capacity and longer cycle stability.

Alloy anodes for sodium-ion batteries

“…The energy storage performance of electrode materials directly relates to their synthetic strategies. The morphology, structure, chemical bonding, and element distribution of electrode materials are originated from their synthetic strategies, thus electrode materials exhibit various energy storage performances [54][55][56][57]. Some synthetic strategies are reviewed in the following sections.…”

“…Thus, calls on effective material [53] design strategies to alleviate the issues and maximize the advantages of Ge-based anodes. Various reports of Gebased anode materials and the corresponding electrochemical performance are summarized in Table 2 [54][55][56][57][58][59][60][61].…”

“…Liu [57] reported a facile method to alleviate the huge volume expansion during the sodiation and desodiation cycles, ultrafine Ge nanoparticles embedded in hierarchical N-doped multichannel carbon fibers were prepared by electrospinning processes, as shown in Fig. 2.…”

Promoting Ge Alloying Reaction via Heterostructure Engineering for High Efficient and Ultra‐Stable Sodium‐Ion Storage

“…[ 20,21 ] However, bulk Ge is undesirable for sodium storage because of the sluggish kinetics. [ 22 ] Besides, the alloying reactions are usually accompanied by huge volume expansion of the host materials, which leads to anode degradation and poor capacity retention. [ 23,24 ] An effective strategy to enhance the reaction kinetics is to design nanostructured heterojunction, which cannot only short the sodium ion diffusion path, but also generate a built‐in electric field at the heterointerfaces, further improving the electrochemical reaction kinetics.…”

Sb2O3 nanoparticles anchored on N-doped graphene nanoribbons as improved anode for sodium-ion batteries

“…26 Great progress has been made to further improve the anode materials for SIBs by combining the merits of doped-carbon nanostructures with conversion-alloying type oxides and chalcogenides (Sn, Sb and Ge). [27][28][29][30] Especially, Sb 2 O 3 has demonstrated appropriate electrochemical performance in SIBs due to its high reactivity with Na ions, i.e., Sb 2 O 3 reacts with 10 sodium ions per mole, delivering a theoretical specic capacity 1103 mA h g À1 . 27 Recently, Li et al 28 reported a Sb/Sb 2 O 3 nanoparticles anchored on 1D N-doped carbon nanober membranes synthesized by electrospinning method and carbon thermal reduction.…”