Two-phase electrochemical lithiation in amorphous silicon.

Lithium-ion batteries have revolutionized portable electronics and will be a key to electrifying transport vehicles and delivering renewable electricity. Amorphous silicon (a-Si) is being intensively studied as a high-capacity anode material for next-generation lithium-ion batteries. Its lithiation has been widely thought to occur through a single-phase mechanism with gentle Li profiles, thus offering a significant potential for mitigating pulverization and capacity fade. Here, we discover a surprising two-phase process of electrochemical lithiation in a-Si by using in situ transmission electron microscopy. The lithiation occurs by the movement of a sharp phase boundary between the a-Si reactant and an amorphous Li(x)Si (a-Li(x)Si, x ~ 2.5) product. Such a striking amorphous-amorphous interface exists until the remaining a-Si is consumed. Then a second step of lithiation sets in without a visible interface, resulting in the final product of a-Li(x)Si (x ~ 3.75). We show that the two-phase lithiation can be the fundamental mechanism underpinning the anomalous morphological change of microfabricated a-Si electrodes, i.e., from a disk shape to a dome shape. Our results represent a significant step toward the understanding of the electrochemically driven reaction and degradation in amorphous materials, which is critical to the development of microstructurally stable electrodes for high-performance lithium-ion batteries.

[1]  K. Tu Selective growth of metal‐rich silicide of near‐noble metals , 1975 .

[2]  E. Kaxiras,et al.  Concurrent Reaction and Plasticity during Initial Lithiation of Crystalline Silicon in Lithium-Ion Batteries , 2012 .

[3]  Ruijuan Xiao,et al.  Investigation of crack patterns and cyclic performance of Ti–Si nanocomposite thin film anodes for lithium ion batteries , 2012 .

[4]  Jian Yu Huang,et al.  Size-dependent fracture of silicon nanoparticles during lithiation. , 2011, ACS nano.

[5]  B. Dunn,et al.  Electrical Energy Storage for the Grid: A Battery of Choices , 2011, Science.

[6]  宁北芳,et al.  疟原虫var基因转换速率变化导致抗原变异[英]/Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A , 2005 .

[7]  Huajian Gao,et al.  Method to deduce the critical size for interfacial delamination of patterned electrode structures and application to lithiation of thin-film silicon islands , 2012 .

[8]  T. D. Hatchard,et al.  In Situ XRD and Electrochemical Study of the Reaction of Lithium with Amorphous Silicon , 2004 .

[9]  Kevin W. Eberman,et al.  Colossal Reversible Volume Changes in Lithium Alloys , 2001 .

[10]  O. Mishima,et al.  Visual Observations of the Amorphous-Amorphous Transition in H2O Under Pressure , 1991, Science.

[11]  Fei Gao,et al.  In situ TEM investigation of congruent phase transition and structural evolution of nanostructured silicon/carbon anode for lithium ion batteries. , 2012, Nano letters.

[12]  S. T. Picraux,et al.  In situ atomic-scale imaging of electrochemical lithiation in silicon. , 2012, Nature nanotechnology.

[13]  H. Ghassemi,et al.  In situ electrochemical lithiation/delithiation observation of individual amorphous Si nanorods. , 2011, ACS nano.

[14]  J. Tarascon,et al.  Pair distribution function analysis and solid state NMR studies of silicon electrodes for lithium ion batteries: understanding the (de)lithiation mechanisms. , 2011, Journal of the American Chemical Society.

[15]  Yi Cui,et al.  Anomalous shape changes of silicon nanopillars by electrochemical lithiation. , 2011, Nano letters.

[16]  P. McMillan Polyamorphic transformations in liquids and glasses , 2004 .

[17]  Ting Zhu,et al.  In Situ TEM Experiments of Electrochemical Lithiation and Delithiation of Individual Nanostructures , 2012 .

[18]  T. Brousse,et al.  Amorphous silicon as a possible anode material for Li-ion batteries , 1999 .

[19]  Brandon R. Long,et al.  Strain Anisotropies and Self‐Limiting Capacities in Single‐Crystalline 3D Silicon Microstructures: Models for High Energy Density Lithium‐Ion Battery Anodes , 2011 .

[20]  T. Zhu,et al.  Atomistic mechanisms of lithium insertion in amorphous silicon , 2011 .

[21]  P. L. Lee,et al.  Polyamorphism in a metallic glass. , 2007, Nature materials.

[22]  Xiqian Yu,et al.  Shape evolution of patterned amorphous and polycrystalline silicon microarray thin film electrodes caused by lithium insertion and extraction , 2012 .

[23]  Jian Yu Huang,et al.  Self-limiting lithiation in silicon nanowires. , 2012, ACS nano.

[24]  M. Armand,et al.  Issues and challenges facing rechargeable lithium batteries , 2001, Nature.

[25]  John P. Sullivan,et al.  In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode , 2010, Science.

[26]  T. D. Hatchard,et al.  Reaction of Li with Alloy Thin Films Studied by In Situ AFM , 2003 .

[27]  J. Goodenough Challenges for Rechargeable Li Batteries , 2010 .

[28]  B. Scrosati,et al.  Lithium batteries: Status, prospects and future , 2010 .

[29]  Yi Cui,et al.  Studying the Kinetics of Crystalline Silicon Nanoparticle Lithiation with In Situ Transmission Electron Microscopy , 2012, Advanced materials.

[30]  Candace K. Chan,et al.  High-performance lithium battery anodes using silicon nanowires. , 2008, Nature nanotechnology.

[31]  Yang Liu,et al.  Anisotropic swelling and fracture of silicon nanowires during lithiation. , 2011, Nano letters.

[32]  Yi Cui,et al.  Fracture of crystalline silicon nanopillars during electrochemical lithium insertion , 2012, Proceedings of the National Academy of Sciences.

[33]  Rangeet Bhattacharyya,et al.  Real-time NMR investigations of structural changes in silicon electrodes for lithium-ion batteries. , 2009, Journal of the American Chemical Society.

[34]  William L. Johnson,et al.  Thermodynamic and kinetic aspects of the crystal to glass transformation in metallic materials , 1986 .

[35]  Candace K. Chan,et al.  Crystalline-amorphous core-shell silicon nanowires for high capacity and high current battery electrodes. , 2009, Nano letters.

[36]  Ruhul Amin,et al.  Phase boundary propagation in large LiFePO4 single crystals on delithiation. , 2012, Journal of the American Chemical Society.

[37]  Yong Liang,et al.  A High Capacity Nano ­ Si Composite Anode Material for Lithium Rechargeable Batteries , 1999 .

[38]  Chunsheng Wang,et al.  Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells , 2007 .

[39]  YuHuang Wang,et al.  Interfacial Mechanics of Carbon Nanotube@Amorphous‐Si Coaxial Nanostructures , 2011, Advanced materials.

[40]  G. Yushin,et al.  High-performance lithium-ion anodes using a hierarchical bottom-up approach. , 2010, Nature materials.

[41]  Mark W. Verbrugge,et al.  Stress Mitigation during the Lithiation of Patterned Amorphous Si Islands , 2011 .

[42]  Z. Suo,et al.  Sandwich-lithiation and longitudinal crack in amorphous silicon coated on carbon nanofibers. , 2012, ACS nano.

[43]  Young-Il Jang,et al.  Electrochemically-driven solid-state amorphization in lithium-silicon alloys and implications for lithium storage , 2003 .