A promising Na3V2(PO4)(3) cathode for use in the construction of high energy batteries

Song, W, Ji, X, Yao, Y, Zhu, H, Chen, Q, Sun, Q and Banks, CE (2014) A promising Na3V2(PO4)(3) cathode for use in the construction of high energy batteries. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 16. ISSN 1463-9076

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Abstract

High-energy batteries need significant cathodes which can simultaneously provide large specific capacities and high discharge plateaus. NASICON-structured Na3V2(PO4)3 (NVP) has been utilised as a promising cathode to meet this requirement and be used in the construction of high energy batteries. For a hybrid-ion battery by employing metallic lithium as an anode, NVP exhibits an initial specific capacity of 170 mA h g 1 in the voltage range of 1.6–4.8 V with a long discharge plateau around 3.7 V. Three Na(2) sites for NVP are found capable to be utilised through the application of a wide voltage window but only two of them are able to undergo ions exchange to produce a NaLi2V2(PO4)3 phase. However, a hybrid-ion migration mechanism is suggested to exist to describe the whole ion transport in which the effects of a Na-ion ‘‘barrier’’ results in a lowered ion diffusion rate and observed specific capacity. 1. Introduction Lithium-ion battery (LIB) technology is critically needed for many applications in a plethora of industries and is an important energystorage solution which can be potentially applied, for instance into electric vehicles (EVs).1,2 However, LIB has continued to be primarily relegated by the electronics market mainly due to its cost and material issues3 and the lack of high-performance cathode materials have become a technological bottleneck for the commercial development of advanced LIB.4 Particularly for the entrance of LIB into high energy fields, such as EVs and renewable energy storage in smart grids, the demand for highcapacity and voltage cathodes is starting to become a key focus of research. In the search for new positive-electrode materials for LIB, recent research has focused upon nano-structured lithium transitional-metal phosphates that exhibit desirable properties such as high energy storage capacities combined with electrochemical stability.5,6 Olivine LiFePO4,7 as one member of this class, has risen to prominence so far due to other characteristics involving low cost, low environmental impact and safety, which are