Robust Anode‐Free Sodium Batteries with Durably Sodophilic Interfaces by Suppressing Sodium‐Alloy Transformation

Abstract

Anode‐free sodium batteries (AFSBs) are a desirable choice for high‐energy‐density and low‐cost battery systems. However, the rapid capacity decline resulting from irreversible sodium plating and stripping remains a big challenge for AFSBs. Herein, a copper‐dominated Cu2Sb composite coating employing a co‐sputtering strategy is designed to improve the sodophilicity of copper foils. The Cu2Sb coating can construct a durably sodophilic and stable interface by suppressing the alloying transition of the sodophilic phase and alleviating the volumetric deformation of the coating. This stable alloy interface can greatly enhance sodium nucleation and improve ion transport at the interface by forming homogeneous NaF‐rich solid electrolyte interphase (SEI) film. Ultimately, the AFSB assembled using this unique substrate with a highly loaded Na3V2(PO4)3 (NVP) cathode (≈10 mg cm−2) can cycle 600 cycles deliver a discharge capacity of 75.4 mAh g−1 with a capacity retention of 74.2%, which is much higher than those of the untreated one or antimony coating one (<30% after 200 cycles). This co‐sputtering strategy provides new insights into the design of sodophilic coatings with sodium‐alloying ability and can be extended to the optimization of zinc‐metal batteries.

Interfacial regulation engineering in anode‐free rechargeable batteries

“…Zn Electrodeposition Anode-free lithium metal batteries [72] Lithiophilic Zn 3 N 2 Filtered cathode vacuum arc technology Anode-free lithium metal batteries [73] Cu 2 Sb Co-sputtering strategy Anode-free sodium batteries [74] Cuprite nanoparticles One-step atmospheric heat treatment method Anode-free lithium batteries [75] Stoichiometric Ti 3 C 2 T x MXene Spin-coating Anode-free lithium metal batteries [76] Au Simply coating Li 2 S-based anode-free full batteries [77] F I G U R E 4 Schematic configurations as well as digital photographs for the anodes that disassembled from the (a) Li 2 S||Cu, (b) Li 2 S||8-Au/Cu as well as (c) Li 2 S||12-Au/Cu cells. The photographs for the anodes that were taken under fully charged status under 3.8 V.…”

“…Various studies have coated different materials to construct composite current collectors, including Zn, [72] lithiophilic Zn 3 N 2 , [73] Cu 2 Sb, [74] cuprite nanoparticles, [75] stoichiometric Ti 3 C 2 T x MXene, [76] Au coating layer, [77] and so forth. Table 2 summarizes the materials, synthesis method, and batteries systems of some typical modification materials.…”

Retarded sodium alloying interface reaction for stable anode-less sodium metal batteries

“…The alloying reaction process activates the interface and induces a uniform distribution of sodium ions, thereby facilitating the nucleation of Pb. 8,13,14…”

“…S25 (ESI†), the Sb–Al@C||NVP cells show a rapid capacity decay due to the loss of interfacial sodiophilicity caused by this rapid sodium alloying reaction. 13 To further investigate the structural changes of Pb during the charging/discharging process, we assembled a half-cell with sodium using a molybdenum mesh microgrid coated with nano-Pb as the working electrode. Following several cycles, the coated molybdenum mesh was transferred for TEM observation after a simple solvent cleaning process.…”

“…The slow alloying process allows Pb to remain in the coating for a longer period of time, enabling the coating to maintain its continuous sodiophilicity, while also reducing the rapid volume expansion that could cause degradation of the coating. 13 Furthermore, density functional theory (DFT) calculations are employed to investigate the interaction between the substrate and sodium. As illustrated in Fig.…”