Overcoming the Unfavorable Kinetics of Na₃V₂(PO₄)₂F₃//SnP_x Full‐Cell Sodium‐Ion Batteries for High Specific Energy and Energy Efficiency

Abstract

In this work, a full‐cell sodium‐ion battery (SIB) with a high specific energy approaching 300 Wh kg−1 is realized using a sodium vanadium fluorophosphate (Na3V2(PO4)2F3, NVPF) cathode and a tin phosphide (SnPx) anode, despite both electrode materials having greatly unbalanced specific capacities. The use of a cathode employing an areal loading more than eight times larger than that of the anode can be achieved by designing a nanostructured nanosized NVPF (n‐NVPF) cathode with well‐defined particle size, porosity, and conductivity. Furthermore, the high rate capability and high potential window of the full‐cell can be obtained by tuning the Sn/P ratio (4/3, 1/1, and 1/2) and the nanostructure of an SnPx/carbon composite anode. As a result, the full‐cell SIBs employing the nanostructured n‐NVPF cathode and the SnPx/carbon composite anode (Sn/P = 1/1) exhibit outstanding specific energy (≈280 Wh kg−1(cathode+anode)) and energy efficiency (≈78%); furthermore, the results are comparable to those of state‐of‐the‐art lithium‐ion batteries.

The Applications of Water‐in‐Salt Electrolytes in Electrochemical Energy Storage Devices

“…[68,69] Generally, the need for the potential window of advanced cathode materials can be met through rational material design. [70,71] For instance, the cation and anion dual doping Na 3 Ti 0.5 V 0.5 (PO 3 ) 3 N was reported by Chen et al, in which both the Ti 3+ /Ti 4+ and V 3+ /V 4+ redox couples are reversibly accessed at 3.3 V (vs Na) and 3.8 V (Vs Na). [70] However, there is a high storage potential of the anode in the currently developed Na-ion batteries, it is more likely to storage energy in anode before the HER potential of H 2 O.…”

High‐efficiency sodium storage of Co0.85Se/WSe2 encapsulated in N‐doped carbon polyhedron via vacancy and heterojunction engineering

“…Additionally, an unbalanced N/P ratio (determined by the ratio of the areal capacity of the anode to cathode) in full cells usually leads to the waste of materials and low CEs during the cycling. It can be improved by adjusting the mass loading ratio of the anode to the cathode 63,64 . Further efforts are needed to focus on the cathode materials and the optimization of the N/P ratio.…”

“…It can be improved by adjusting the mass loading ratio of the anode to the cathode. 63,64 Further efforts are needed to focus on the cathode materials and the optimization of the N/P ratio. Moreover, the energy density (E) of the CoWSe/NCP//PB sodium ion full cell was calculated by the following Equation 1 65,66 :…”

Full-cell C/SiO2ǁNa3V2(PO4)3 high-performance Na-ion battery: Diffusion kinetics and N/P optimization

“…The most popular cathode materials today can refer to polyphosphate-based compounds such as (Na 3 V 2 (PO 4 ) 3 , Na 2 FeP 2 O 7 ) or Prussian blue NaFe[Fe(CN) 6 ], Na 2 CoFe(CN) 6 ). These materials all have high speci c capacities ranging 80 mAh.g − 1 to 128 mAh.g − 1 [3] [4]. Furthermore, various anode materials, including hard carbon, alloys (Sn, Sb, Si, and P), and metal oxides/sul des (SiO 2 , TiO 2 , Sb 2 S 3 ), have been studied.…”