Invited Presentation: In Situ Nanomechanics of Electrode Failure in Lithium-Ion Batteries

Lithium-ion batteries revolutionize portable electronics and are key to next-generation electric vehicles. However, they often suffer from the electrochemically induced mechanical degradation in high-capacity electrodes, resulting in capacity fade and short cycle life. Using a unique nanobattery cell inside a transmission electron microscope, we made in situ observations of reaction, deformation and fracture in individual nanowire and nanoparticle electrodes. A wide range of novel phenomena were discovered, including the size dependent fracture in silicon nanoparticles, anisotropic swelling in silicon nanowires, two-phase lithiation in amorphous silicon, nanoporosity formation in germanium nanowires, and cracking in the coating of tin oxide nanowires. We further developed the continuum and atomistic models to reveal the mechanistic origin of stress generation and mechanical failure in these high-capacity electrode materials. The results provide insights into the microstructural evolution and degradation in nanoscale building blocks of battery electrodes, and have broad implications for designing the durable electrodes in high performance lithium-ion batteries.