Development Of Sodium-ion Batteries Research Articles

Manganese hexacyanomanganate open framework as a high-capacity positive electrode material for sodium-ion batteries.

Potential applications of sodium-ion batteries in grid-scale energy storage, portable electronics and electric vehicles have revitalized research interest in these batteries. However, the performance of sodium-ion electrode materials has not been competitive with that of lithium-ion electrode materials. Here we present sodium manganese hexacyanomanganate (Na2MnII[MnII(CN)6]), an open-framework crystal structure material, as a viable positive electrode for sodium-ion batteries. We demonstrate a high discharge capacity of 209 mAh g(-1) at C/5 (40 mA g(-1)) and excellent capacity retention at high rates in a propylene carbonate electrolyte. We provide chemical and structural evidence for the unprecedented storage of 50% more sodium cations than previously thought possible during electrochemical cycling. These results represent a step forward in the development of sodium-ion batteries.

Electrochemical Activity of P2 Structured Na-M-O Cathode for Sodium Ion Batteries

A market of plug-in electric vehicles (PEV) or hybrid electric vehicles (HEV) using lithium ion battery is being expanded, then demand for large-scale energy storage devices is increasing gradually. However, percentage mass of lithium in the earth is only 0.006%. Indeed, the cost of lithium resource increased after commercialization in 1991, might be soared when EVs or energy storage systems (ESS) are used. Sodium resource, the element which is quite abundant (Clarke’s number is 2.64), can be an alternative for the expensive and rare lithium. For those reasons, development of sodium ion battery is essential for solving previous problems. Recently, P2-phase materials are widely attracted due to their large initial capacity. However, obvious capacity fading is shown in almost P2 type active materials. In this study, we report to synthesize P2 structured Na-M-O (where M is transition metal) compounds and investigate physical and electrochemical behaviors of the Na-M-O cathode for sodium-ion batteries.The Na-M-O powders were synthesized by solid-state method. Stoichiometric mixture of Na2CO3 and precursor were mixed by ball-milling. Then the mixed powders were pelletized, and the pellets were calcined at high temperature. After calcination, heated pellets were quenched. All chemicals and products were handled in an Ar-filled gloved box to avoid air exposure. Phase identification of calcined products was done by X-ray diffraction (XRD) with Cu Kα radiation and the collected XRD data were analyzed by using the Rietveld refinement program, Fullprof. Electro-chemical test were carried out in a 2032 coin type sodium cell. Galvanostatic electrochemical charge and discharge tests in 0.5M NaPF6 EC:DEC solutions were carried out at room temperature. Also, the products were characterized by SEM, TEM and so on.The XRD patterns of Na-M-O compounds were obtained without impurities peak, respectively. The produced materials showed P2 phase even if adding other transition metal elements. Electrochemical tests were observed in the potential domain between 2.0 and 4.5 V at 20 mA g-1 current density. Initial capacity of Na-M-O electrodes showed high capacity. And the capacity retention was significantly improved by adding other transition metal elements. Details will be discussed in the conference site.

Structural Investigation of Na2MnSiO4, a Novel Cathode Material for Rechargeable Sodium Ion Batteries

Lithium ion batteries dominate the world’s requirements of portable power storage due to their superior energy and power capability. However, as the focus of battery applications shifts towards larger scale energy storage, placing pressure on the declining amount of usable lithium, research interests shift towards the development of sodium ion batteries. Recently, various sodium based cathode materials have been based on structures that allow lithium insertion. Mixed-polyanion lithium compounds have been shown to be suitable precursors as they have the structural stability required for the complete exchange of lithium with sodium.1 The silicates Li2 MSiO4, (M = Mn and Fe), fulfil today’s requirements of safe, cheap and sustainable cathode materials especially due to the abundance of iron, manganese and silicon. The relatively higher theoretical capacities for these materials arise due to the possible extraction of two lithium ions accessing the M 2+/M 3+ and M 3+/M 4+ redox couples.2 The clear advantages of Li2 MSiO4, (M = Mn and Fe), over other lithium insertion compounds have made these materials attractive as possible analogues for cathode materials in Na-ion batteries.While the structure of Na2MnSiO4 (monoclinic, space group Pn) has been reported previously employing conventional X-ray diffraction technique,3 the possibility of this compound to be utilised as a cathode material in sodium ion batteries has not been explored. To date, we have been able to synthesise the Na2MnSiO4 and investigated the structural parameters of the compounds through the combination of synchrotron X-ray and neutron powder diffraction studies. This contribution will also address the electrochemical behaviour of this compound, including structural changes which occur in Na2MnSiO4during electrochemical cycling and the connection of these structural changes to the observed properties.