Nanostructured Si/C Fibers as a Highly Reversible Anode Material for All-Solid-State Lithium-Ion Batteries

Abstract

This study demonstrates the application of Si/C composite fibers as anode materials for all-solid-state lithium-ion batteries. Using polyacrylonitrile as the carbon precursor, Si/C fibers were prepared through electrospinning and subsequent heat-treating processes. To investigate the correlation between fiber diameter and electrochemical performance, we prepared three electrodes (A, B, C), containing Si/C fibers with ∼2 μm, ∼1 μm and ∼0.1 μm diameters, respectively. Our results revealed that although the composition of all three electrodes was nearly the same, the Si/C fiber based electrodes exhibited better capacity retention when their fiber diameters were smaller. Normalized to the total mass of electrode composite, the solid-state half-cell prepared with the smallest diameter (∼0.1 μm) Si/C fibers achieved a reversible specific capacity of ∼700 mAh g −1 (normalized to electrode mass) over 70 cycles. We believe that this report can serve as an informative approach toward the utilization of electrospun Si/C fibers as anode materials for all-solid-state lithium-ion batteries. Lithium-ion batteries (LIBs) have widely been used as portable energy storage devices owing to their great reversibility, long cycle life and high power output without memory effect.1,2 However, current LIBs utilizing conventional organic liquid electrolytes still have significant safety risks, such as operational instability at elevated temperatures, leakage of hazardous solvents and ignition by external damages.3-6 To overcome these safety risks, the development of the all-solid-state lithium-ion battery (SLIB) has attracted considerable attention. [3][4][5][6][7][8][9][10][11] In the SLIB configuration, a highly Li-ion conductive solid-state electrolyte (SSE) layer is deployed between positive and negative electrodes in place of the organic liquid electrolytes typically used in LIBs. This replacement of the liquid electrolyte with a highly conductive ceramic material is expected to improve both the SLIB's thermal and mechanical stabilities.To date, graphite has been extensively used as an anode material in LIBs; however, its limited capacity (372 mAh g −1 ) has been regarded as a drawback to achieving higher energy density LIBs. Silicon is considered to be a promising anode material alternative to graphite due to its large theoretical capacity (3,579 mAh g −1 ), low cost and high earth abundance.9,11-17 To achieve such a high capacity, Si inevitably undergoes a massive volume expansion/contraction process when alloying/de-alloying with Li. 18,19 Since the repeated volume changes of Si particles during cycling causes cracking, pulverization and rapid capacity fading brought on by the electrochemical isolation of active materials, it is believed that an effective accommodation of this Si volume change is essential for achieving acceptable capacity retention in these anodes. 20One effective strategy to accommodate the extreme volume changes of Si is to limit its extent of alloying with Li by introducing resilient additives into the electro...

Lignin/Si Hybrid Carbon Nanofibers towards Highly Efficient Sustainable Li-ion Anode Materials

“…The addition of inorganic nanostructures with a high theoretical capacity such as Si (3579 mAh g -1 ), ZnO (978 mAh g -1 ) or GeO 2 (2152 mAh g -1 ), has been previously utilised to provide a remarkable improvement in the gravimetric capacity of petroleum derived CNFs. [19][20][21][22] However, in this work, we have developed a new and unique mesoporous hybrid Si/CNFs derived from fully sustainable precursors which reach a capacity of 921 mAh g -1 with only 15% Si loading. This represents not only a massive opportunity for lignin valorisation in the battery industry but also highlights the potential of sustainable materials as advanced materials with performance levels higher than their fossil equivalents, therefore reaching beyond the current state of the art whilst offering enormous commercial opportunities.…”

Recent advances of non-lithium metal anode materials for solid-state lithium-ion batteries

“…This may be due to the more delicate PAN fibers preventing the Si nanoparticles from agglomerating into larger clusters during the electrospinning process, reducing the generation of crystalline Li x Si phases, and improving the cycle performance of the electrode. 80 Coal-tar-pitch (CTP) is a high-quality precursor for synthesizing functional carbon materials such as carbon microspheres, carbon fibers, and carbon foam. Nathan et al obtained conductive amorphous carbon by pyrolysis of CTP, and a negative electrode prepared by compounding it with silicon particles exhibits an initial reversible capacity of 621.3 mA h g −1 .…”

Strategies for Controlling or Releasing the Influence Due to the Volume Expansion of Silicon inside Si−C Composite Anode for High-Performance Lithium-Ion Batteries

“…(1) Highest theoretical specific capacity (approximately 4200 mAh g −1 ), which is much higher than other types of anode materials [51,52]; (2) Abundant reserves (the second-highest content in the Earth's crust), affordable, environmentally friendly, and non-toxic [53]; (3) Discharge potential is low (<0.5 V) [54,55], which mitigates safety issues, due to the growth of lithium dendrites [56][57][58].…”