Demonstration of in Situ Formed Li2NaV2(PO4)3 as a Strain-Free Lithium Battery Anode

With a view to exploit the advantageous switching oxidation state property of vanadium and to reap the beneficial effects of the single plateau behavior, Na3V2(PO4)3 (NVP) has been chosen instead of popularly known Li3V2(PO4)3 (LVP), and the former was converted into Li2NaV2(PO4)3 (LNVP) through a simple site-selective ion-exchange reaction. Furthermore, custom-engineered LNVP/human hair-derived carbon (HHC) with the incorporation of HHC has been prepared to combat the multiple plateau behavior of LVP and the lower theoretical capacity of NVP. The LNVP/HHC anode exhibits a specific capacity of 370 mA h g–1 at 50 mA g–1 for up to 150 cycles. Even at 86 C, a specific capacity of 33 mA h g–1 can be extracted for up to 1000 cycles, without any significant capacity loss. Herein, the involvement of strain-free insertion/extraction process and ion-exchange mechanism has been confirmed through ex situ and in-plane X-ray diffraction analyses.