High‐Energy/Power and Low‐Temperature Cathode for Sodium‐Ion Batteries: In Situ XRD Study and Superior Full‐Cell Performance

Abstract

Sodium-ion batteries (SIBs) are still confronted with several major challenges, including low energy and power densities, short-term cycle life, and poor low-temperature performance, which severely hinder their practical applications. Here, a high-voltage cathode composed of Na V (PO ) O F nano-tetraprisms (NVPF-NTP) is proposed to enhance the energy density of SIBs. The prepared NVPF-NTP exhibits two high working plateaux at about 4.01 and 3.60 V versus the Na /Na with a specific capacity of 127.8 mA h g . The energy density of NVPF-NTP reaches up to 486 W h kg , which is higher than the majority of other cathode materials previously reported for SIBs. Moreover, due to the low strain (≈2.56% volumetric variation) and superior Na transport kinetics in Na intercalation/extraction processes, as demonstrated by in situ X-ray diffraction, galvanostatic intermittent titration technique, and cyclic voltammetry at varied scan rates, the NVPF-NTP shows long-term cycle life, superior low-temperature performance, and outstanding high-rate capabilities. The comparison of Ragone plots further discloses that NVPF-NTP presents the best power performance among the state-of-the-art cathode materials for SIBs. More importantly, when coupled with an Sb-based anode, the fabricated sodium-ion full-cells also exhibit excellent rate and cycling performances, thus providing a preview of their practical application.

3D Electronic Channels Wrapped Large‐Sized Na3V2(PO4)3 as Flexible Electrode for Sodium‐Ion Batteries

“…The low points in the profiles located at around 3.4 V correspond well to the potential plateaus in the charge–discharge curves. The minimum ion diffusion coefficient D Na+ values in the plateau region can be ascribed to the strong interactions between the host matrix and the intercalation ions during the two‐phase transition reaction, indicating a kinetically fast and close to equilibrium state . Such similar phenomena have also been detected in other electrode materials such as LiFePO 4 and Na 3 V 2 (PO 4 ) 2 O 2 F .…”

“…The minimum ion diffusion coefficient D Na+ values in the plateau region can be ascribed to the strong interactions between the host matrix and the intercalation ions during the two‐phase transition reaction, indicating a kinetically fast and close to equilibrium state . Such similar phenomena have also been detected in other electrode materials such as LiFePO 4 and Na 3 V 2 (PO 4 ) 2 O 2 F . At the end of charge process, both of the two electrodes display a relatively lower diffusion coefficients, indicating the end of phase transition during the charge process.…”

Micro/Nanostructured Materials for Sodium Ion Batteries and Capacitors

“…In addition to the high working potential, O 2− ‐substituted Na 3 (VO 1− x PO 4 ) 2 F 1+2x (0 ≤ x < 1) materials have a higher valence state of V and lower polarization. Recently, Na 3 V 2 (PO 4 ) 2 O 2 F nanotetraprisms (NVPF‐NTP) have been proposed by Guo et al, and the prepared NVPF–NTP material exhibited a high energy density up to 486 W h kg −1 . Moreover, due to the low volumetric variation (2.56%) and excellent Na transport kinetics, an excellent high‐rate capability and low‐temperature performance were obtained (Figure c,d).…”

Positive Surface Pseudocapacitive Behavior‐Induced Fast and Large Li‐ion Storage in Mesoporous LiMnPO4@C Nanofibers

“…[24] D Li is the Li + diffusion coefficient at 298 K, n is the number of electrons involved in the redox process (n = 1f or Mn 2 + /Mn 3 + redox pair), and n is the sweep rate (V s À1 ). As every LMP cell contains four Li + ,1cm 3 contains4 3.30 10 21 /(6.02 10 23 ) = 2.20 10 À2 mol Li + .This means the Li + concentrationi sa pproximately 2.20 10 À2 mol cm À3 .…”