Carbon nanotube directed three-dimensional porous Li₂FeSiO₄ composite for lithium batteries

Lithium iron silicate (Li₂FeSiO₄) is capable of affording a much higher capacity than conventional cathodes, and thus, it shows great promise for high-energy battery applications. However, its capacity has often been adversely affected by poor reaction activity due to the extremely low electronic and ionic conductivity of silicates. Here, we for the first time report on a rational engineering strategy towards a highly active Li₂FeSiO₄ by designing a carbon nanotube (CNT) directed three-dimensional (3D) porous Li₂FeSiO₄ composite. As the CNT framework enables rapid electron transport, and the rich pores allow efficient electrolyte penetration, this unique 3D Li₂FeSiO₄-CNT composite exhibits a high capacity of 214 mAh·g⁻¹ and retains 96% of this value over 40 cycles, thus, outstripping many previously reported Li₂FeSiO₄-based materials. Kinetic analysis reveals a high Li⁺ diffusivity due to coupling of the migration of electrons and ions. This research highlights the potential for engineering 3D porous structure to construct highly efficient electrodes for battery applications.