硅基锂离子电池负极材料由于能量密度高、工作电压适中而受到全世界的关注,但硅基材料存在体积膨胀和动力学较差等缺陷,该问题严重限制了硅基负极材料的大规模应用。文章提出了一种将纳米尺寸的介孔Si颗粒封装在碳中的设计策略,该Si@C...硅基锂离子电池负极材料由于能量密度高、工作电压适中而受到全世界的关注,但硅基材料存在体积膨胀和动力学较差等缺陷,该问题严重限制了硅基负极材料的大规模应用。文章提出了一种将纳米尺寸的介孔Si颗粒封装在碳中的设计策略,该Si@C纳米复合材料的尺寸约为200 nm左右。将Si@C以不同比例(20 wt%、30 wt%、40 wt%)和石墨混合、球磨合成,从而最终制备得到硅–石墨锂离子电池负极材料,通过包覆的碳层和复合的石墨层提高LIBs的能量密度和高稳定性。在本工作的研究中我们发现Si@C/G (20 wt%)纳米复合材料在100次循环中表现出600 mAh∙g−1的高比容量,在0.5 A∙g−1的电流密度下实现了750次的稳定循环,展现了优秀的循环稳定性,平均充电/放电容量为360 mAh∙g−1。此外,在不同电流密度下测试了Si@C/G (20 wt%)复合电极,并在1 A∙g−1下显示出262 mAhg−1的相对较高的可逆容量。与其他两种复合材料相比,Si@C/G (20 wt%)表现出高容量和稳定性。Si@C/G (20 wt%)获得的电化学性能证明了低含量合成纳米硅与石墨的高兼容性。此外,碳涂层防止了充电/放电过程中Si的体积膨胀。这个想法可以应用于设计高能量密度LIB负极材料。Silicon-based anodes for lithium-ion batteries (LIBs) are attractive due to their high energy density, but challenges such as significant volume expansion and poor kinetics have limited their practical application. This work introduces a Si@C nanocomposite, where nano-sized mesoporous silicon particles are encapsulated in carbon, with particle sizes around 200nm. The Si@C was blended with graphite at ratios of 20 wt%, 30 wt%, and 40 wt%, then ball-milled to form composite anode materials. The Si@C/G (20 wt%) composite demonstrated superior electrochemical performance, maintaining a high specific capacity of 600 mAh∙g⁻¹ over 100 cycles and stable cycling up to 750 times at 0.5 A∙g⁻¹, with an average charge/discharge capacity of 360 mAh∙g⁻¹. At higher current densities, it showed good reversible capacity retention, reaching 262 mAh∙g⁻¹ at 1 A∙g⁻¹. The carbon coating effectively mitigated silicon’s volumetric changes during cycling, enhancing stability. This study highlights the effectiveness of integrating low-content nano-silicon with graphite for achieving high-performance LIB anodes, showcasing the potential of Si@C/G (20 wt%) composites for next-generation battery technology. Moreover, the carbon coating prevented the volume expansion of Si during the charge/discharge process. This concept can be applied in designing high-energy-density LIB anode materials.展开更多
文摘硅基锂离子电池负极材料由于能量密度高、工作电压适中而受到全世界的关注,但硅基材料存在体积膨胀和动力学较差等缺陷,该问题严重限制了硅基负极材料的大规模应用。文章提出了一种将纳米尺寸的介孔Si颗粒封装在碳中的设计策略,该Si@C纳米复合材料的尺寸约为200 nm左右。将Si@C以不同比例(20 wt%、30 wt%、40 wt%)和石墨混合、球磨合成,从而最终制备得到硅–石墨锂离子电池负极材料,通过包覆的碳层和复合的石墨层提高LIBs的能量密度和高稳定性。在本工作的研究中我们发现Si@C/G (20 wt%)纳米复合材料在100次循环中表现出600 mAh∙g−1的高比容量,在0.5 A∙g−1的电流密度下实现了750次的稳定循环,展现了优秀的循环稳定性,平均充电/放电容量为360 mAh∙g−1。此外,在不同电流密度下测试了Si@C/G (20 wt%)复合电极,并在1 A∙g−1下显示出262 mAhg−1的相对较高的可逆容量。与其他两种复合材料相比,Si@C/G (20 wt%)表现出高容量和稳定性。Si@C/G (20 wt%)获得的电化学性能证明了低含量合成纳米硅与石墨的高兼容性。此外,碳涂层防止了充电/放电过程中Si的体积膨胀。这个想法可以应用于设计高能量密度LIB负极材料。Silicon-based anodes for lithium-ion batteries (LIBs) are attractive due to their high energy density, but challenges such as significant volume expansion and poor kinetics have limited their practical application. This work introduces a Si@C nanocomposite, where nano-sized mesoporous silicon particles are encapsulated in carbon, with particle sizes around 200nm. The Si@C was blended with graphite at ratios of 20 wt%, 30 wt%, and 40 wt%, then ball-milled to form composite anode materials. The Si@C/G (20 wt%) composite demonstrated superior electrochemical performance, maintaining a high specific capacity of 600 mAh∙g⁻¹ over 100 cycles and stable cycling up to 750 times at 0.5 A∙g⁻¹, with an average charge/discharge capacity of 360 mAh∙g⁻¹. At higher current densities, it showed good reversible capacity retention, reaching 262 mAh∙g⁻¹ at 1 A∙g⁻¹. The carbon coating effectively mitigated silicon’s volumetric changes during cycling, enhancing stability. This study highlights the effectiveness of integrating low-content nano-silicon with graphite for achieving high-performance LIB anodes, showcasing the potential of Si@C/G (20 wt%) composites for next-generation battery technology. Moreover, the carbon coating prevented the volume expansion of Si during the charge/discharge process. This concept can be applied in designing high-energy-density LIB anode materials.
