Cathode nanoarchitectonics with Na₃VFe_0.5Ti_0.5(PO4)₃: Overcoming the energy barriers of multielectron reactions for sodium‐ion batteries

Abstract

High electrochemical stability and safety make Na⁺ superionic conductor (NASICON)‐class cathodes highly desirable for Na‐ion batteries (SIBs). However, their practical capacity is limited, leading to low specific energy. Furthermore, the low electrical conductivity combined with a decline in capacity upon prolonged cycling (>1000 cycles) related to the loss of active material‐carbon conducting contact regions contributes to moderate rate performance and cycling stability. The need for high specific energy cathodes that meet practical electrochemical requirements has prompted a search for new materials. Herein, we introduce a new carbon‐coated Na₃VFe_0.5Ti_0.5(PO₄)₃ (NVFTP/C) material as a promising candidate in the NASICON family of cathodes for SIBs. With a high specific energy of ∼457 Wh kg⁻¹ and a high Na⁺ insertion voltage of 3.0 V versus Na⁺/Na, this cathode can undergo a reversible single‐phase solid‐solution and two‐phase (de)sodiation evolution at 28 C (1 C = 174.7 mAh g⁻¹) for up to 10,000 cycles. This study highlights the potential of utilizing low‐cost and highly efficient cathodes made from Earth‐abundant and harmless materials (Fe and Ti) with enriched Na⁺‐storage properties in practical SIBs.