ZnS quantum dots@multilayered carbon: geological-plate-movement-inspired design for high-energy Li-ion batteries

Abstract

Nowadays, much progress has been made in designing practical high-energy-density anode materials for lithium-ion batteries (LIBs). However, during repeated charge–discharge cycles, high-energy-density anode materials usually undergo large volume changes, which results in a limited cycle life. The situation is worse when anode materials have high tap densities and low porosities. Herein, inspired by the Earth that can release its inner stresses to maintain its structural stability through geological plate movements, a novel slippage strategy is proposed to tackle the above-mentioned problem. We fabricate a ZnS quantum dots@multilayered N-doped carbon matrix (ZnS-QDs@mNC), where ZnS quantum dots are well-dispersed in N-doped carbon nanosheets, which assemble into micro-sized particles via intertwined overlapping. In situ transmission electron microscopy demonstrates that the carbon nanosheets of ZnS-QDs@mNC slide against each other during lithiation, similar to geological plates, which can make full use of the limited gaps between the carbon nanosheets to reduce the volume expansion of the ZnS-QDs@mNC anode to only 6.5% (much lower than the industrially acceptable value of ∼30%). As a result of this structural stability, ZnS-QDs@mNC with a high tap density of 0.86 g cm⁻³ and low total pore volume of 0.092 cm³ g⁻¹ demonstrates excellent Li-storage properties even when the areal capacity is increased to 1.82 mA h cm⁻².