Restraining Capacity Increase To Achieve Ultrastable Lithium Storage: Case Study of a Manganese(II) Oxide/Graphene‐Based Nanohybrid and Its Full‐Cell Performance

Abstract

As is well known, a gradual increase in capacity during cycling is a common phenomenon in previously reported oxide‐based anodes for lithium‐ion batteries. However, not only may this be superfluous for practical applications, but it may also imply the presence of some electrochemical instabilities and side reactions. To achieve ultrastable Li storage without such a gradual increase in capacity, the mechanism of this increase by using a MnO/graphene‐based nanohybrid (MnO@C/RGO) as an example was comprehensively explored. Then, the gradual increase behavior of the specific capacity was effectively restrained by rationally optimizing the cutoff voltage, which resulted in the MnO@C/RGO electrode maintaining a nearly constant capacity during cycling at different current densities. Taking the high current density of 2 A g−1 as an example, there was no clear capacity change (increase/attenuation) even over 2000 cycles with stable coulombic efficiencies of around 99.7 %. This ultrastable Li‐storage capability should mainly benefit from rational testing parameters and an optimal 3D conductive network. More importantly and interestingly, full cells were also assembled and tested by coupling MnO@C/RGO and commercial LiFePO4 as the anode and cathode materials, respectively. The full cells impressively exhibited superior rate performance and excellent cycling stability.

Interfacial Superassembly of Grape-Like MnO–Ni@C Frameworks for Superior Lithium Storage

“…Third, the generating the gel-like film on the electrode surface enhances their capacity. Many efforts have been made to relieve this phenomenon. , …”

“…Many efforts have been made to relieve this phenomenon. 58,59 In order to further investigate the mechanism of the outstanding stable cycle performance through the introduction of metallic Ni particles, a thermodynamic calculation was performed to clarify the mechanism of the phase transition of the Ni−Mn−O system during cycling processes. The phase diagrams were computed using the Thermo-Calc package 60 based on the thermodynamic modeling Ni−Mn−O system 61 to identify the phase relationship, and the calculated roomtemperature phase diagram of the Ni−Mn−O system is presented in Figure S11.…”

3D Hierarchical Microballs Constructed by Intertwined MnO@N‐doped Carbon Nanofibers towards Superior Lithium‐Storage Properties

“…Until now, lithium‐ion batteries (LIBs) remain dominant as power sources in a myriad of applications because of their high theoretical capacity, high energy density, and low cost. However, the theoretical capacity of commercial graphite anode is limited to 372 mA h g −1 and can hardly satisfy the challenging requirements of rapid growing markets . Tto improve the energy density of LIBs, to pursuit advanced anode materials with higher specific capacity is necessary .…”

Chemical Vapor Deposition-Assisted Fabrication of Self-Assembled Co/MnO@C Composite Nanofibers as Advanced Anode Materials for High-Capacity Li-Ion Batteries

“…A high of 1324 mA h g –1 can be even reached after 1000 cycles. The high capacity and superior stability can be attributed to (1) the carbon coated on the nanofibers that serves as a buffer for the metallic oxide; consequently, the broken nanoparticles were fixed in the carbon layers rather than falling off from the material, thus providing a strong stability in the charge–discharge process; (2) the fractured active substance which was wrapped up by the carbon exposed more active sites, improving the kinetics for the Li ions binding and releasing; (3) the existence of metal Co nanoparticles can promote the reversible reaction in the SEI films and improve the electrochemical stability of samples; and (4) Mn 2+ in the MnO may oxidize to a higher valence state which causes the increase of capacity. − The cycling stability of Co/MnO@C 10 min was also tested for comparison. The sample presents a similar trend to Co/MnO@C 5 min but only arrived at a capacity of 536 mA h g –1 after 1000 cycles, which may be due to the proportion of active substances being relatively low compared to the samples of Co/MnO@C 0 min and Co/MnO@C 10 min.…”