Microstructural degradation of Ni-rich cathode materials is a major bottleneck limiting their widespread applications, originating from their microcracks due to lattice strain. Herein, a facile lattice engineering strategy (praseodymium substitution at octahedral 3b Ni sites) is constructed to greatly reduce the lattice strain of the LiNi0.9Co0.05Mn0.05O2 cathode. The relationship between the lattice strain and electrochemical performance is systematically examined to gain insights into the Pr activity-governing mechanisms. Furthermore, the experimental and DFT calculations reveal that praseodymium substitution not only reduces the lattice strain during the de-/lithiation and enhances the electronic activity near the Fermi level but also reduces local stress buildup by refining the primary particles to grow along the radial direction. The ameliorated LiNi0.9Co0.05Mn0.05O2 shows low lattice strain and achieves a record capacity retention of 92.3% after 100 cycles, higher than that of the original sample (capacity retention of 78.7%). Moreover, it still exhibits an ultrahigh capacity of 168 mA h·g–1 even at 10 C due to a lower Li+ migration energy barrier. This work deeply investigates the information on the bulk structure, electronic properties, and interaction mechanism between substitution cations and Ni-rich layered oxides, which provides a new insight into the design and construction of advanced high-capacity cathode materials.

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In this paper, we report a complete solution for enhanced sludge treatment involving the removal of toxic metal (Cu(II)) from waste waters, subsequent pyrolytic conversion of these sludge to Cu-doped porous carbon, and their application in energy storage systems. The morphology, composition, and pore structure of the resultant Cu-doped porous carbon could be readily modulated by varying the flocculation capacity of Cu(II). The results demonstrated that it exhibited outstanding performance for supercapacitor electrode applications. The Cu(II) removal efficiency has been evaluated and compared to the possible energy benefits. The flocculant dosage up to 200 mg·L−1 was an equilibrium point existing between environmental impact and energy, at which more than 99% Cu(II) removal efficiency was achieved, while the resulting annealed product showed a high specific capacity (389.9·F·g−1 at 1·A·g−1) and good cycling stability (4% loss after 2500 cycles) as an electrode material for supercapacitors.

This work reports for the first time an in situ synthesis of a NiAl-layered double hydroxide (NiAl-LDH) with a tunable interlayer spacing using a confined impinging jet microreactor (CIJ). It is found that CIJ allows simultaneous guest (water molecules and carbonate) intercalation and in situ growth of NiAl-LDH by imposing a proper micromixing scale in a space-confined mixing chamber. The final interlayer spacing of NiAl-LDH can be easily regulated from 0.9 to 3.6 nm by tuning the Reynolds number flow range from 4.8 × 103 to 6.7 × 102. The supercapacitor has been chosen as a model reaction to investigate the electrochemical activity of NiAl-LDHs. Results demonstrate that a higher interlayer space increases the electrochemical activity and enhances supercapacitor performances due to improvement in space accessibility of NiAl-LDHs during the faradaic redox reaction. NiAl-LDH with an interlayer space up to 3.6 nm presents fairly good performance as a supercapacitor electrode material in terms of specific capacitance (1285.2 F·g–1 at 1 A·g–1) and stability (capacitance retention rates over 80% after 5000 cycles). This work develops a rapid and continuous flow methodology for a one-pot, in situ formation of NiAl-LDH with the controlled interlayer spacing via microreactor technology.