Ultrastable Sodium/Potassium Metal Anode Enabled by a Multifunctional Interphase Layer with Enhanced Ion Transport Kinetics

Abstract

Na (K) metal batteries (NMB and KMB) have gained tremendous attention as large‐scale energy storage systems because of their high specific capacity, low working potential, and natural abundance. However, severe Na dendrite growth hinders the practical application of Na (K) anode. Here, a multifunctional interphase layer consisting of fast‐ion conductive Na–Bi (K–Bi) alloy and sodiophilic (potassiophilic) Na3VO4 (K3VO4) phases, which i derived from a spontaneous reaction (denoted as BVO@Na or BVO@K), is proposed and prepared. The designed electrode exhibits enhanced ion transport kinetics and homogenous Na (K) deposition behavior, and finally achieving dendrite‐free Na (K) growth. Accordingly, the BVO@Na displays a high Na plating/stripping reversibility of 960 h at 1.0 mA cm−2, 1.0 mAh cm−2, and the BVO@K electrode can be operated a cycle lifespan of 870 h under 1.0 mA cm−2, 2.0 mAh cm−2 in symmetric cells. In BVO@Na||Na3V2(PO4)3 full battery, it shows remarkable cycling stability (91% of capacity retention after 1900 cycles) and a high energy density of 281 Wh kg−1 at a power density of 16.2 kW kg−1. The findings lend credence to the prospect of the multifunctional interface layer contributing to the design of a protective layer for alkali metal anodes.

Dynamically Evolving Multifunctional Protective Layer for Highly Stable Potassium Metal Anodes

“…When the current density and fixed capacity are increased to 1 mA cm –2 and 1 mAh cm –2 , respectively, the protected K symmetric cell still maintains a small polarization voltage and delivers a long cycle life of 1000 h. The performance is much better than that of the bare K symmetric cell that fails within 28 h (Figure c and Figure S5 of the Supporting Information). As shown in Figure b, the cycling stability of the protected K symmetric cell is better than that of most relevant works and recently reported K metal symmetric cells. − ,,,− …”

“…Various strategies have been carried out to solve the above issues, and constructing an artificial protective layer on the electrode surface has proven to be one of the most effective methods. , For example, the protective layer derived from SbF 3 can effectively prevent electrode corrosion . Protective layers constructed using red P, Te powder, and BiVO 4 have high ionic conductivity and can inhibit dendrite growth. − Thus far, the formation of an artificial protective layer can be classified into in situ and ex situ . The operation of forming a protective layer in situ by electrolyte engineering is relatively simple, but many electrolyte additives are gradually consumed as the cycling proceeds and are not satisfactory in carbonate electrolytes. , The composition and properties of the ex situ protective layer can be precisely designed, while most fabrication methods are too complex or expensive .…”

A Rooted Multifunctional Heterogeneous Interphase Layer Enabled by Surface‐Reconstruction for Highly Durable Sodium Metal Anodes

“…According to the previous research, the theoretical Young's modulus of Na metal is ≈2.3 GPa and such soft property is especially vulnerable to Na dendrites. [46] In contrast, as shown in Figure 1f and Figure S10 (Supporting Information), the Na/SnSe heterogeneous interlayer possesses a high flatness as well as a much larger Young's modulus of 13.2 GPa, which illustrates that the designed artificial SEI layer has sufficient capability to inhibit the growth of Na dendrite and to ensure the mechanical stability of the interface during consistent Na deposition. [47,48] To accurately demonstrate the crystal texture of the as-prepared artificial SEI layer, X-ray diffraction (XRD) pattern was performed (Figure 1g).…”

“…Visibly, the redox peaks are higher and the region of the loop curve is larger for the Na/SnSe anode compared to those of the bare Na metal, demonstrating excellent reaction kinetics for the Na/SnSe cell (Figure S19a, Supporting Information). [46] Concurrently, the reaction reversibility is also assessed by CV measurement for the initial three cycles at a voltage range from −0.3 to 1.0 V. Impressively, the CV curves of the Na/SnSe||Cu half-cell exhibit an overlapping profile in comparison with the bare Na metal, which suggests a superior reaction reversibility (Figure S19b,c, Supporting Information). At the same time, the variation of the coulombic efficiency in half-cells is also collected and it can be seen that the coulombic efficiency of the Na/SnSe||Cu cells quickly increases to more than 80% after initial Na plating and stripping cycles and remains ≈92% after 30 cycles, whereas the corresponding value of the bare Na||Cu half-cell merely keeps ≈87% with dramatic fluctuations in the repeated plating and stripping curves (Figure S19d-f, Supporting Information).…”

Synergy of Cu-foam/Sb2O3/rGO for stable potassium anodes of high-rate and low-temperature potassium metal batteries

“…When combined with the cathode electrode, it enables the attainment of elevated battery voltage and energy density. 15,16 However, the identified issues in KMB development such as severe volume expansion, dendrite growth, and an unstable solid-state electrolyte interface (SEI) have impeded the practical application of KMBs due to the fast degradation and premature failure during cycling.…”