ZnO‐Based Conversion/Alloying Negative Electrodes for Lithium‐Ion Batteries: Impact of Mixing Intimacy

Abstract

Conversion/alloying materials, such as transition metal (TM)‐doped ZnO, are showing superior performance over pure ZnO due to the presence of the TM, enabling the reversible formation of Li2O due to the enhanced electronic conductivity within the single particle once being reduced to the metallic state upon lithiation. Herein, the impact of introducing Co as representative TM at the atomic level in ZnO compared with mixtures of nano‐ and microsized CoO and ZnO is investigated. While even rather simple mixtures provide higher capacities than pure ZnO, an intimate mixing of nanoparticulate CoO and ZnO leads to a further increase due to the more homogeneous dispersion of Co. Nonetheless, the “atomic mixing” via doping still provides the highest capacities—for both nano‐ and microparticles, thus highlighting the importance of the very fine distribution of Co (and generally the TM) for realizing effective electron conduction pathways to enable the reversible formation of Li2O.

Stabilization of the Solid-Electrolyte-Interphase Layer and Improvement of the Performance of Silicon–Graphite Anodes by Nanometer-Thick Atomic-Layer-Deposited ZnO Films

“…For example, the broad peak at ∼1.34 V was observed for ZnO nanosheet anodes from the redox reaction between Zn and Li 2 O . Similarly, a broad anodic peak centered at 1.3 V for the reconversion reaction was observed for nano- and microsized ZnO and CoO mixed/doped ZnO electrodes …”

“…35 Similarly, a broad anodic peak centered at 1.3 V for the reconversion reaction was observed for nano-and microsized ZnO and CoO mixed/doped ZnO electrodes. 37 The rate capability of the Si/Gr electrodes was examined using a sequence of 5 charging/discharging cycles each, at different C-rates of 0.1, 0.2, 0.5, 1, 2, 0.2, and 0.1 after the formation cycle at a C-rate of 0.05. The first cycle CE for the pristine Si/Gr electrode was 72.1% (Figure 3a).…”

ZnO‐Embedded Expanded Graphite Composite Anodes with Controlled Charge Storage Mechanism Enabling Operation of Lithium‐Ion Batteries at Ultra‐Low Temperatures

“…ZnO reversibly interacts with Li through the conversion reaction (ZnO + 2Li + + 2e À ↔ Zn 0 + Li 2 O) and the (de)alloying reaction (Zn 0 + xLi + + xe À ↔ Li x Zn). [45] Two cathodic peaks at 0.3 and 0.8 V were commonly assigned to the Zn-Li alloying and conversion reactions, respectively. [27] The anodic CV scan showed the multi-step dealloying reaction between 0.4 and 0.7 V and the conversion reaction at 1.35 V. [29] In addition, the redox peaks at low potential, below 0.3 V, can be ascribed to the Li + intercalation reactions to EG.…”

Synergistic Effect of Co and Mn Co-Doping on SnO2 Lithium-Ion Anodes

“…Such CAMs as, for instance, TM-doped ZnO, GeO 2 , or SnO 2 , provide superior specific capacity, energy density, and energy efficiency compared with pure conversion-type materials [10][11][12][13], while the volume variation is significantly suppressed compared with pure alloying compounds [14]. The key towards such superior performance is the introduction of the TM, as this limits the aggregation of the alloying domains and provides an electronically conductive network throughout the initial particle [15][16][17]. The latter is important to enable the reversible formation of Li 2 O, which presumably aids the buffering of the volume variation.…”