CONTEXT

There are currently some discussion about Li-ion battery especially related to their cost. Raw lithium material costs is almost multiply by 2 since the first Li-ion battery in 1991 and is still increasing due to the market demand. In addition there is some concern about the lithium ressource which is located only in a few places and which could not cope with the dramatically increasing demand due to auomotive transportation and grid related applications.
Na-ion batteries could become an alternative thank to the better availability of Na and the lower cost of its precursors.
Lot of work was dedicated to cathode material but graphite whch is widely used as anode, is not as suitable as for Li due to the size difference of ionic radius of Na ion (>55% Li-ion).
Current material such as hard carbon or even Sb are not satisfactory. Hard carbon exhibits a capacity fading due to passivation layer onto the carbon surface.

TECHNICAL DESCRIPTION

In the present work, the inventors have developped a new anodic material for Na-ion battery based on derivative of Na₂Ti₃O₇.
The active material of the electrode material is composed of an oxide with astructure corresponding to the layered structure of the compound Na₂Ti₃O₇, said oxide conforming to the formula Na_xTi(IV)_aTi(III)_bM_cO₇, in which x denotes the number of Na⁺ ions inserted between the layers, per Ti₃O₇ structural unit, with 0<x≤5; Ti(IV) and Ti(III) represent titanium in the oxidation states IV and III, respectively; M represents one or more elements selected from 3d transition metalsand 4d transition metals.
The electrode material is obtained by electrochemical reduction of an oxide Na_x’Ti(IV)_a’M_cO₇.

BENEFITS

Low cost precursor materials
Availibility of sodium
No need of high temperature such as in Zebra type batteries

DEVELOMENT STAGE

Suitable process for 1-2-gram scale synthesis;

INDUSTRIAL APPLICATIONS

Na-ion anode in replacement of hard carbon

For further information, please contact us (Ref 04634-01)