A facile route to synthesize multiporous MnCo2O4 and CoMn2O4 spinel quasi-hollow spheres with improved lithium storage properties

Abstract

A facile and general way for the synthesis of porous and hollow complex oxides is highly desirable owing to their significant applications for energy storage and other fields. In this contribution, uniform Mn(0.33)Co(0.67)CO(3) and Co(0.33)Mn(0.67)CO(3) microspheres are firstly fabricated solvothermally just by tuning the molar ratio of Mn and Co. Subsequently, the growth of multiporous MnCo(2)O(4) and CoMn(2)O(4) quasi-hollow microspheres by topotactic chemical transformation from the corresponding precursors are realized through a non-equilibrium heat treatment process. Topotactic conversion further demonstrated that the much larger CoMn(2)O(4) pores than those of MnCo(2)O(4) are possibly due to the longer transfer distance of ions. When evaluated as anode materials for LIBs (lithium ion batteries), after 25 cycles at a current density of 200 mA g(-1), the resultant MnCo(2)O(4) and CoMn(2)O(4) quasi-hollow microspheres possessed reversible capacities of 755 and 706 mA h g(-1), respectively. In particular, the MnCo(2)O(4) samples could deliver a reversible capacity as high as 610 mA h g(-1) even at a higher current density of 400 mA g(-1) with excellent electrochemical stability after 100 cycles of testing, indicating its potential application in LIBs. We believe that such good performance results from the appropriate pore size and quasi-hollow nature of MnCo(2)O(4) microspheres, which can effectively buffer the large volume variation of anodes based on the conversion reaction during Li(+) insertion/extraction. The present strategy is simple but very effective, and due to its versatility, it can be extended to other binary, even ternary complex metal oxides with high-performance in LIBs.

Hollow MnCo2O4 Submicrospheres with Multilevel Interiors: From Mesoporous Spheres to Yolk-in-Double-Shell Structures

“…In contrast to the carbonate precursor reported in previous work, [12][13][14][15][16]18 the MnCo-glycolate could yield a large weight loss due to the presence of a large amount of organic species by heating under atmosphere, the progress of which well controlled the different types of interiors. As commonly observed, the TEM and FESEM images in Fig.…”

“…[5][6][7][8] Heterogeneous contraction, for example, is a typical and effective route for controlled synthesis of hollow structure with different interiors, which is caused by non-equilibrium heat treatment and determined by the difference between the cohesive force and the adhesive force generated by a high heating rate. 18 However, the hollow structure is obtained as it is after calcinations and cannot be tuned because of the smaller weight loss. Therefore, it is still a great challenge to form the hollow structures for binary metal oxide with controlling interiors, despite of its popularity in simple metal oxide.…”

“…The results indicate that the solid-state redox couples Mn 3+ /Mn 2+ and Co 3+ /Co 2+ coexist in the structure, which is similar to what has been previously reported. 18 The ratios are shown in Table S1 based on the areas of deconvoluted peaks.…”

Simple synthesis of yolk-shelled ZnCo2O4 microspheres towards enhancing the electrochemical performance of lithium-ion batteries in conjunction with a sodium carboxymethyl cellulose binder

“…Two distinguishable satellite peaks centered at 789.7 and 804.7 eV were detected at ~9.0 eV above the Co 2p 3/2 and 2p 1/2 main lines, which are the fingerprint for recognition of Co 3+ species [31,32].…”

Self‐Sacrifice Template Fabrication of Hierarchical Mesoporous Bi‐Component‐Active ZnO/ZnFe2O4 Sub‐Microcubes as Superior Anode Towards High‐Performance Lithium‐Ion Battery

“…This phenomenon is generally attributed to the reversible formation of a polymeric gel-like fi lm originating from kinetic activation in the electrode. [ 15,[46][47][48] More impressively, the discharge capacity of the ZZFO remains relatively stable after continuously cycling for ≈100 times, and is even kept as high as ≈837 mAh g −1 over 200 cycles. As seen from the FESEM and TEM images of the ZZFO anode after 200 cycles at the current rate of 1000 mA g −1 , some SMCs still can be evident (see Figure S11, Supporting Information), suggesting its desirable structural stability over cycling, which should be well responsible for the excellent cycling performance.…”