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A structure of 3D porous hierarchical networks is highly desired for mass production of electrode materials for lithium‐ion batteries due to its unique role in promoting battery performance. Herein, a general strategy using expanded graphites as both a structure‐directed template and a solution container is proposed for the synthesis of various cathode materials with 3D porous hierarchical networks formed by the crosslinkage of monolayered primary nanoparticles interconnected nanoplates, which all show high capacity, superior cyclic performance, and rate capability. The LiNi0.8Co0.15Al0.05O2/Li half cell delivers a capacity of 118 mAh g−1 at 20 C (5.6 A g−1) and capacity retention of 71.6% after 1000 cycles at 1 C, while the LiNi0.8Co0.15Al0.05O2/graphite full cell shows 79.9% and 80.0% capacity retentions after 1400 cycles at 1 C and 3000 cycles at 5 C, respectively. The superior performance is attributed to the unique 3D porous hierarchical networks with a stable surface and structure, which is related to the sufficient oxidization of Ni2+ and the formation of little residual lithium at surface intrinsic to this strategy. The study opens a generalized new avenue for facile, cheap, green, and mass production of various oxide materials with 3D porous hierarchical networks. [ABSTRACT FROM AUTHOR]

Surface state and/or bulk structure, which are determined by different synthesis conditions, have a significant effect on the performance of an electrode material. Distinguishing their individual roles in the performance can provide guidance for the synthesis of high‐performance electrode materials. Cobalt‐free and nickel‐rich LiNi0.9Mn0.1O2, a promising cathode material, is synthesized in air and oxygen to show remarkable differences in both surface state and structure using a facile sol–gel method. Li2CO3 formed at the surface during the synthesis in air results in much poorer performance than in oxygen, which can be significantly improved by the effective removal of Li2CO3 through ultrasonic treatments without changing the bulk structure, morphology, and size. The surface state, instead of bulk structure, morphology, and size‐related elements like more severe cationic mixing and larger secondary particles, is predominantly responsible for the performance difference between the samples synthesized in air and oxygen, which is beyond the conventional viewpoints on layered compounds. This study provides a new perspective for exploring novel synthesis approaches of high‐performance cobalt‐free and nickel‐rich layered compounds. Nickel‐rich LiNi0.9Mn0.1O2 layered compounds synthesized in air and oxygen, A‐LNMO and O‐LNMO, show Li2CO3 layers with different thicknesses, which are predominantly responsible for their different performances. The Li2CO3 layer of A‐LNMO with larger thickness can be significantly reduced or removed by ultrasonication to remarkably improve its rate capability. [ABSTRACT FROM AUTHOR]

Abstract Li- and Mn-rich layered oxides can deliver high reversible capacity but suffer from severe voltage decay, which seriously impedes their commercial applications. However, high-nickel Li-rich layered oxides could normally present stable discharge voltage but tend to deliver low reversible capacity. In this work, high-nickel Li-rich layered oxides are doped by Mo via a facile sol-gel route to realize both high reversible capacity and minor voltage decay simultaneously. The superior performance could be ascribed to the reduced size of primary particles, the enhanced stability of lattice oxygen and more Mn4+/3+ redox couples effectively activated during the electrochemical reactions which are realized via Mo doping. The present study offers a new strategy to achieve high-performance high-nickel Li-rich layered oxides with both the stable discharge potential and high reversible capacity by modifying their morphologies, structures and chemistries via the introduction of proper alien elements which are believed to be the potential cathode candidates for next generation lithium-ion batteries. Highlights • Single phase Li 1.2 Ni 0.4 Mn 0.36 Mo 0.04 O 2 was synthesized via a facile sol-gel recipe. • Mo doping modifies the morphology and chemistry of high-nicke Li-rich Li 1.2 Ni 0.4 Mn 0.4 O 2. • Mo doping improves the rate capability of Li 1.2 Ni 0.4 Mn 0.4 O 2 significantly. • Mo doping increases capacity via oxygen loss reduction and more Mn4+/3+ redox couples activation. [ABSTRACT FROM AUTHOR]

LiMn 2 O 4 cathode materials have been regarded as one of the promising candidates for aqueous zinc-ion batteries. However, their actual application is still hindered by the Mn2+ dissolution and structural transformation during the charge/discharge cycling. Herein, we synthesized LiMn 2 O 4 cathode materials with octahedron morphologies and followed introducing oxygen vacancies by the calcination treatment in Ar. Octahedral shape is beneficial to the improvement of cycle stability of LiMn 2 O 4 cathode materials. Oxygen vacancies contribute to the rate performance by improving the electronic conductivity. Nevertheless, the cycling stability of LiMn 2 O 4 cathode materials with oxygen vacancies is not satisfactory. So, we proposed the synergistic strategy of TiO 2 -coating LiMn 2 O 4 and oxygen vacancies. TiO 2 @(LMO-A0.5) sample with uniform thin TiO 2 coating was obtained by regulating the hydrolysis reaction of tetrabutyl titanate. Consequently, TiO 2 @(LMO-A0.5) exhibits the impressive rate capability and cycling stability (as high as 85 mAh/g and 91.22% capacity retentions after 200 cycles at 0.1 A g−1) as the cathode materials for aqueous zinc-ion batteries. The synergetic development of multiple strategies may endow LiMn 2 O 4 cathode materials with magical perspectives in aqueous zinc-ion batteries. [ABSTRACT FROM AUTHOR]