Embedding MnO@Mn₃O₄ Nanoparticles in an N‐Doped‐Carbon Framework Derived from Mn‐Organic Clusters for Efficient Lithium Storage

Abstract

The first synthesis of MnO@Mn O nanoparticles embedded in an N-doped porous carbon framework (MnO@Mn O /NPCF) through pyrolysis of mixed-valent Mn clusters is reported. The unique features of MnO@Mn O /NPCF are derived from the distinct interfacial structure of the Mn clusters, implying a new methodological strategy for hybrids. The characteristics of MnO@Mn O are determined by conducting high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and electron energy loss spectroscopy (EELS) valence-state analyses. Due to the combined advantages of MnO@Mn O , the uniform distribution, and the NPCF, MnO@Mn O /NPCF displays unprecedented lithium-storage performance (1500 mA h g at 0.2 A g over 270 cycles). Quantitative analysis reveals that capacitance and diffusion mechanisms account for Li storage, wherein the former dominates. First-principles calculations highlight the strong affiliation of MnO@Mn O and the NPCF, which favor structural stability. Meanwhile, defects of the NPCF decrease the diffusion energy barrier, thus enhancing the Li pseudocapacitive process, reversible capacity, and long cycling performance. This work presents a new methodology to construct composites for energy storage and conversion.

Hierarchically Pomegranate‐Like MnO@porous Carbon Microspheres as an Enhanced‐Capacity Anode for Lithium‐Ion Batteries

“…What's more, the PCMS@MnOÀ M electrode still keeps a high reversible capacity of 935 mAh g À 1 and a nearly 100 % CE after 100 cycles. [27,37,48,49] The unique pomegranate-like micro-nano structure of PCMS@MnOÀ M enables the ultrahigh capacity, which is higher than the theoretical capacity. The phenomenon could be accounted for the pseudocapacitive effect of PCMS@MnOÀ M during chargedischarge process.…”

“…Interestedly, in the subsequent CV cycles, the cathodic reduction peak shifts from 0.11 V to about 0.45 V for the PCMS@MnOÀ M, indicating the improved reaction kinetics and the stabilization of SEI layer after the first lithiation process. [11,[47][48][49] However, there is no obvious peak at 2.07 V for the pure MnO, suggesting that pure MnO is hardly to be further oxidized because of slow reaction kinetics ( Figure S5a). Significantly, a weak oxidation peak at 2.07 V (see inset in Figure 6a) is ascribed to further oxidization of Mn 2 + in PCMS@MnOÀ M to higher oxidation state, resulting in enhanced capacity in the following charge-discharge cycles.…”

“…[48,54] And the b-value can be determined by the slope of the lg v ð Þ versu lg i ð Þ plots. [48,54] And the b-value can be determined by the slope of the lg v ð Þ versu lg i ð Þ plots.…”

Pseudocapacitive Lithium Storage in Three‐Dimensional Cobalt‐Doped MnO/Nitrogen‐Doped Reduced Graphene Oxide Aerogels as High‐Rate Anode Material

“…The nitrogen atoms in rGO could enhance the intimate interaction between Co−MnO and rGO, resulting in excellent cycling performance ,. For the Mn 2p spectrum of 3D Co−MnO/NG‐G (Figure f), the peaks at 641.7 and 653.4 eV are attributed to the Mn 2p 3/2 and Mn 2p 1/2 , respectively . Compared with that of 3D MnO/NG‐G, the Mn 2p 3/2 and Mn 2p 1/2 peaks of 3D Co−MnO/NG‐G shift to high binding energy resulting from the reduction of electron cloud around Mn 2p.…”

Rational Design of Porous TiO2@N‐Doped Carbon for High Rate Lithium‐Ion Batteries

“…Figure b shows the Ln( i ) vs Ln( v ) plots at cathodic and anodic processes of the CV curves, and all the values of b are close to 1 (as shown in Table S1, Supporting Information), which indicates that the surface capacitive contribution plays a significant role in the charge–discharge process of the TiO 2 @NC composite. To further investigate the capacitive contribution at a given scan rate, the ratios of surface capacitive contribution and diffusion‐controlled contribution are quantified by the following equation …”