Electrode materials with fast charging/discharging capability is important to high power density sodium ion batteries (SIBs). In this talk, I will introduce our recent effort on high rate cathode and anode materials for SIBs. For cathode, we systematically studied fluorine loss and structure transformation of Na3V2(PO4)2F3 during typical carbon thermal reduction. Based on the understandings, we designed and synthesized materials based on Na3V2(PO4)2F3 and Na3V2(PO4)3, where large capacity, high rate and long cycle life are achieved. Even when the current density is increased to 100C, the capacity remains 83 mAh g-1, which is 80% of that at 1C. For anode, we synthesized black K2Ti6O13 (B-KTO) nanowires via a hydrothermal method followed by calcination and hydrogen plasma reduction. The B-KTO anode can deliver a reversible capacity of 103 mA h g-1 at 20C. The nanowires could sustain at least 20,000 cycles without apparent capacity fade. Our first-principles calculations indicate that the electrical conductivity of K2Ti6O13 would be enhanced while the sodiation energy barrier could be reduced after introducing oxygen vacancies via hydrogen plasma.

High-rate electrode materials for sodium-ion batteries

2019 Fall National Meeting

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