Synchronous Densification and Conductivity Modulation of Nano-Titanate for Pseudocapacitive Li-ion Storage

Abstract

Nanostructured electrode materials have attracted enormous attention because of their kinetic advantages endorsed by nanoscale regime. Densification is required to improve their volumetric densities for practical applications but is challenged by the loss of kinetic features. In this work, a nano-densification strategy is developed by co-sintering nanosized titanate with a phosphate agent and acid-treated carbon black. Experimental studies reveal that the formation of Ti─O─P bonds energetically facilitates the dissociation of crystal water in titanate, enabling lower-temperature consolidation of the nanostructures that avoids grain growth. Simultaneously, phosphorylation improves charge carrier concentration and electron conductivity of the titanate. Together with the incorporation of hydrophilic carbon black, the treated nano-titanate electrode reaches a bulk-level compaction density of 2.35 g cm−3. As an anode for Li-ion batteries, the densified electrode shows improved electrochemical performance with a specific capacity of 88.4 mA h g−1 at 20 A g−1. When pairing with a high-voltage LiNi0.5Mn1.5O4 cathode, the hybrid device demonstrates an outstanding combination of energy and power densities. Open access publishing facilitated by The University of Queensland, as part of the Wiley - The University of Queensland agreement via the Council of Australian University Librarians.