Ultrathin phyllosilicate nanosheets as anode materials with superior rate performance for lithium ion batteries

Abstract

Phyllosilicates with SiO₄ tetrahedra and metal cation-containing octahedrally composed sheet structures are promising anode materials for lithium-ion batteries, as they have high abundance and three times the theoretical capacity of graphite. The main challenges associated with the phyllosilicate anode are the structural degradation and the low rate capability caused by the low intrinsic electrical conductivity and the large strain upon cycling. Herein, we develop hybrid architectures by in situ inlaying nickel phyllosilicate within tubular carbon frameworks to form ultrathin phyllosilicate nanosheets, where the phyllosilicate is spatially incorporated within carbon rather than superficially coating on the outer surface. The carbon framework significantly enhances the electrical conductivity and steadily buffers volumetric strain of the ultrathin phyllosilicate nanosheets upon cycling. The tubular hybrid architectures can provide accessible electroactive sites and allow rapid electron/ion transfer. When applied as lithium-ion battery anode materials, the prepared hierarchical nickel phyllosilicate/carbon hybrids deliver an exceptional rate capability (1017 mA h g⁻¹ at 0.2 A g⁻¹ and 540 mA h g⁻¹ at 2.0 A g⁻¹) and good cycling stability (585 mA h g⁻¹ after 200 cycles at 1.0 A g⁻¹), and outperform the previously reported nickel silicate materials. A full cell constructed with the nickel phyllosilicate anode and a commercial LiNi_1/3Co_1/3Mn_1/3O₂ cathode exhibits high reversible capacity in the voltage range of 0.2–4.0 V, demonstrating the great potential of phyllosilicates as anode materials.