An integrated interfacial engineering for efficiently confining the asymmetric strain in scalable silicon anode

Abstract

Silicon (Si) has become one of the most promising candidates as the anode for the next-generation high-energy-density lithium-ion batteries. High Si content is leading to the extraordinary asymmetric strain between the Si nanoparticles and current collector, which is regarded as the fundamental reason for the constant accumulation of solid electrolyte interphase, destruction in conductive network, and exfoliation of the active material, thus generating low Coulombic efficiency and short lifespan. In order to settle these detrimental effects by the asymmetric strain, an integrated interfacial engineering is developed, in which the as-formed 3D interpenetrating graphdiyne network on the Si nanoparticles is physically and chemically rooted on the array-like current collector. The enhanced interface interactions efficiently absorb the in-plane shear energy to resist in-plane deformation, resulting in out-plane-only volume deformation in the lithiation/delithiation reactions. Compared to the in-plane strain within the compression cell, the out-plane strain should be controllable, and the array-like architecture further provides an elastic space for reversibly accommodating the out-plane strain of electrodes. The method effectively reduces the stripping and volume variation of Si particles and provides a stable interface and robust ion/electron transport network. These advantages render Si anode extraordinary cyclability and rate performance, and the areal capacity is greatly increased to 7.5 mAh cm−2.