A Nanowire Nest Structure Comprising Copper Silicide and Silicon Nanowires for Lithium‐Ion Battery Anodes with High Areal Loading

Abstract

expansion during charge (300% when fully lithiated). [9][10][11][12][13] The build-up of mechanical stress through expansion of the active layer causes a loss of electrical contact with the non-expanding current collector, exacerbating capacity fade. Nanostructuring can alleviate mechanical stress build-up through smaller particle sizes, structural porosity and void spaces. [9,10] Nanoparticles (NPs), [14][15][16][17] nanowires (NWs), [18][19][20][21][22][23][24][25] and nanotubes (NTs) [26][27][28][29] are the most widely used morphologies, allowing for structural relaxation through shortened diffusion channels, increased porosity and larger surface area to volume ratios.Cu is the optimal current collector for lithium-ion battery anodes, due to its superior electrical conductivity over stainless steel (SS) and other carbon-based substrates. However, direct growth of Si on Cu yields electrochemically inactive CuSi compounds. [30][31][32] Alternatively, slurry-based Si electrodes suffer from issues of capacity fade as harsh expansion leads to electrical contact loss with the current collector. [33][34][35] Also, issues of capacity fade are heightened for thicker slurry layers, behaving similarly to bulk Si. [36,37] Si composites with graphite have gained huge popularity over recent years, synergistically combining the high lithiation capacity of Si with the low cost, stability, and scalability of carbon. [38][39][40][41][42] Graphite incorporation can alleviate instability issues common with Si-rich electrodes. [43,44] Karuppiah et al. demonstrated impressive long-term stability of slurry-based electrodes of Si NWs directly grown on graphite, retaining 87% capacity after 250 cycles versus Li metal. [44] Similarly, Datta et al. found that Si/graphite stability could be further enhanced through amorphous carbon coating, removing direct contact between Si and the electrolyte, and delivering a stable capacity of 660 mAh g −1 . [45] Slurry-based composites allow for high achievable Si loadings while maintaining anode stability. However, thick slurry layers suffer from poor fast-rate performance and inactive slurry additions negatively impact energy density. [46][47][48][49] The incorporation of Si into metallic or carbonbased frameworks like Mxenes, [50,51] graphene, [52,53] CNTs, [54,55] and CNFs [56,57] has allowed considerable improvements in cell stability, although the continued presence of inactive slurry components increases dead weight. Directly grown electrodes offer a multitude of advantages over slurry-based configurations, however, achieving stable performance of high loading binder-free Si electrodes has historically been difficult.High loading (>1.6 mg cm −2 ) of Si nanowires (NWs) is achieved by seeding the growth from a dense array of Cu 15 Si 4 NWs using tin seeds. A one-pot synthetic approach involves the direct growth of CuSi NWs on Cu foil that acts as a textured surface for Sn adhesion and Si NW nucleation. The high achievable Si NW loading is enabled by the high surface area of CuSi NWs and bolst...

Constructing Biomass‐Based Ultrahigh‐Rate Performance SnOy@C/SiOx Anode for LIBs via Disproportionation Effect

“…[39] This phenomenon is more visible when voltage is lower than 0.3 V, especially for this material. Moreover, major lithiation peaks at 1.1, 0.53, 0.25, 0.13, and near 0.01 V corresponds to the mixture phase transition of SnO y and SiO x , [40,41] formation of Li x Sn through the Sn with Li + and insertion of Li + into C layer, [42,43] the alloying process of Li-Si, [44,45] mixture alloying reactive of Li-Sn and Li-Si, [46][47][48] the mixture of Si-Li alloys and Lithium-insert C layer, [49,50] respectively. Noteworthy, the lithiation peak at 0.25 V, which appears in the second cathodic scan and presents in all subsequent cycles, can give evidence that Si exists in SnO y @C/ SiO x -50 and is activated by impregnation of electrolyte with the battery cycling gradually.…”

Dense Silicon Nanowire Networks Grown on a Stainless‐Steel Fiber Cloth: A Flexible and Robust Anode for Lithium‐Ion Batteries

“…A C/5 rate represents a 5 h charge/discharge based on the experimental specific capacity of 2200 mAh g −1 for Sn‐seeded Si NW@SSFC. [ 8b,23 ] The cycling performance of all electrodes at C/5 is presented in Figure S7 (Supporting Information). The initial reversible capacities are 2233.5, 2185.1, 2029, and 2019.2 for electrodes with 0.24, 0.52, 1.03, and 1.32 mg cm −2 mass loadings, respectively, and corresponding capacities of 1735.8, 1486.7, 1290.8, and 1241.5 mAh g −1 were retained after 110 cycles.…”

Scalable Layer-by-Layer Stacking of the Silicon-Graphite Composite: Prelithiation Strategy of the High-Capacity Anode for Energy/Power-Dense Li Batteries

“…Confining the nanostructured Si (nanoparticles, − nanowires, − and nanosheets − ) within the carbonaceous matrix is considered as the mitigation strategy to alleviate the volume expansion and retarded kinetics . Among the host scaffolds, graphite and its lower-dimensional derivatives demonstrate the industrial scalability, cost efficiency, and intrinsic merits of the electrical conductivity and mechanical robustness .…”