Electrodeposited ZnO/Zn(OH)2 Nanosheets as a Functional Interface for Dendrite-Free Lithium Metal Anodes

Abstract

Modifying the current collector is a promising strategy to enable Li metal anodes with minimal Li consumption. Herein, a scalable electrodeposition method is introduced to construct 3D ZnO/Zn(OH)₂ nanosheets on Cu foil (ZOH NSs-Cu foil). Cu(OH)₂ nanowires are first formed via anodization, followed by electroconversion of Cu²⁺ and Zn²⁺ ions. DFT calculations reveal that the ZOH NSs-Cu foil exhibits high Li adsorption energy, imparting strong lithiophilicity and lowering the Li nucleation overpotential. The 3D nanosheet structure provides a large electrochemically active surface, reducing the effective current density. Furthermore, ZOH NSs-Cu foil exhibits low charge transfer resistance and promotes a Li₂O/LiF-rich solid electrolyte interphase (SEI) layer, further reducing interfacial resistance. SEM analysis and simulations confirm uniform Li deposition on ZOH NSs-Cu foil. In asymmetric cells (1 mAh cm^-2 at 1 mA cm^-2), ZOH NSs-Cu foil supports stable cycling for over 400 cycles. Furthermore, a full cell coupling a LiFePO₄ (LFP) cathode with a Li@ZOH NSs-Cu foil anode retains high capacity with ≈100% Coulombic efficiency over 350 cycles at 1 C, even at an N/P ratio of ≈1.9. This binder-free, scalable approach offers precise Li deposition control and excellent electrochemical performance, advancing the practical application of Li metal anodes.

Keywords: ZnO/Zn(OH)2 nanosheets; current collector modification; electrodeposition method; lithium metal anode; solid electrolyte interphases.

Scheme 1

Schematic illustration of the fabrication procedure for ZOH NSs–Cu foil.

Figure 1

a) LSV curves of Cu foil, and Cu(OH)₂ NWs–Cu foil during the reaction in ZnSO₄ solution. b) XRD patterns of Cu(OH)₂ NWs–Cu foil at 1 V (initial state), 0.7 V, and 0.3 V (post‐reduction). Top‐view SEM images of c) 1 V, d) 0.7 V, and e) 0.3 V. f) Cross‐sectional SEM image of ZOH NSs–Cu foil. g) TEM images of ZOH NSs–Cu foil. The inset shows the corresponding fast Fourier transform (FFT) pattern and inverse FFT of the orange square region. h) Corresponding selected‐area electron diffraction (SAED) pattern.

Figure 2

a) Voltage‐capacity curves of Cu(OH)₂ NWs–Cu foil at different current densities in ZnSO₄ solution. b) Top‐view SEM image of ZOH NSs–Cu foil obtained through the LSV method. c–e) Surface evolution at different current densities during the electroconversion of Cu(OH)₂ NWs–Cu foil to ZOH NSs–Cu foil. XPS Spectra of ZOH NSs–Cu foil: f) Zn 2p and g) O 1s. h) Atomic ratios of Cu, O, and Zn in ZOH NSs–Cu foil.

Figure 3

Top‐view SEM images of Cu foil, Cu(OH)₂ NWs–Cu foil, and ZOH NSs–Cu foil after pre‐lithiation and Li deposition. (a,e,i) Pre‐lithiation, (b,f,j) 0.1 mAh cm⁻², (c,g,k) 0.5 mAh cm⁻², and (d,h,l) 3 mAh cm⁻².

Figure 4

a) Top and side views of the Li adsorption configurations on ZnO (011). b) Comparison of adsorption energy of a Li atom with Cu (001), Cu(OH)₂ (021), and ZnO (011). c) Li nucleation overpotential on various current collectors at current density of 1 mA cm⁻². d) CV curves of asymmetric cells with Cu foil, Cu(OH)₂ NWs–Cu foil, and ZOH NSs–Cu foil at a scan rate of 10 mV s⁻¹. e) Nyquist plots of Cu foil, Cu(OH)₂ NWs–Cu foil, and ZOH NSs–Cu foil. XPS spectra of Cu foil and ZOH NSs–Cu foil: f) O 1s and g) F 1s. h) COMSOL simulations of Li deposition on the Cu foil and ZOH NSs–Cu foil: potential distribution. i) ECSA of the heat‐treated Zn foil (ZnO) and ZOH NSs–Cu foil.

Figure 5

Electrochemical performance of asymmetric and symmetric cells with different current collectors. a) CEs of asymmetric cells with Cu foil, Cu(OH)₂ NWs–Cu foil, and ZOH NSs–Cu foil at a current density of 1 mA cm⁻² with a capacity of 1 mAh cm⁻². b) Voltage–capacity curves at a current density of 1 mA cm⁻² with a capacity of 1 mAh cm⁻² at the 200^th cycle. c) Voltage–time profiles of symmetric cells with Li@Cu foil, Li@Cu(OH)₂ NWs–Cu foil, and Li@ZOH NSs–Cu foil at a current density of 1 mA cm⁻² with a capacity of 1 mAh cm⁻² after Li pre‐deposition of 3 mAh cm⁻². d) Rate performance of symmetric cells at current densities ranging from 0.5 to 10 mA cm⁻² with a capacity of 1 mAh cm⁻². e) Voltage–time profiles at a current density of 1 mA cm⁻² with a capacity of 1 mAh cm⁻² after Li pre‐deposition of 5 mAh cm⁻².

Figure 6

Electrochemical performance of full cells with different anodes paired with the LFP cathode. a) Cycling performance of Li@Cu foil, Li@Cu(OH)₂ NWs–Cu foil, and Li@ZOH NSs–Cu foil at 1 C (N/P ratio ≈1.9). b–d) Voltage profiles of the three full cells at 1 C. e) Cycling performance of Li@Cu foil, Li@Cu(OH)₂ NWs–Cu foil, and Li@ZOH NSs–Cu foil at 1 C (N/P ratio ≈0.7). f) Rate performance of full cells with Li@Cu foil, Li@Cu(OH)₂ NWs–Cu foil, and Li@ZOH NSs–Cu foil.