Stress-relieving defects enable ultra-stable silicon anode for Li-ion storage

Graphite-like coated silicon ([email protected]) material has been shown to be only partly useful in addressing the technological problems of high-capacity Si anodes in lithium ion batteries (LIBs). This is because of inevitable and large internal stresses in a [email protected] structure induced by instantaneously explosive expansion of Si upon lithiation which destroys the graphitic matrix, and leads to the uncontrolled growth of a solid-electrolyte interphase (SEI) layer, and severe capacity fading. Therefore, it is vital to develop a novel internal-stress-relief strategy for [email protected] of the next-generation stable LIBs anodes. Herein, being inspired by a relief valve, we design a nitrogen-doped carbon layer coating on Si nanoparticles ([email protected]) to effectively relief the volume expansion of Si spheres during lithiation. Such homogenous N-doping in each graphitic layer generates uniformly-distributed "hole" defects in the NG network and guarantees a stress relief in the lithiated [email protected] to the maximum extent possible. Therefore, when tested as an anode material for LIBs, [email protected] shows superior cycling stability (1321 mAh·g−1 after 100 cycles at the current density of 2100 mA g−1, about 96.6% capacity retention) and ultra-high initial coulombic efficiency (ICE) of 90.3%.