Co ₃ O ₄ hollow dodecahedrons with controllable interiors are prepared through direct pyrolysis of ZIF-67 and exhibit high performance for Li-ion storage.

Silicon offers an extremely high theoretical specific capacity, but suffers from dramatic volume change during lithiation/delithiation processes, which typically leads to rapid anode degradation. Here we designed a facile and self-assembly strategy to construct a three-dimensional (3D) polymeric network as a promising binder for high-performance silicon submicro-particle (SiSMP) anodes through in situ interconnection of alginate chains by additive divalent cations. The highly cross-linked alginate network exhibits superb mechanical properties and strongly interacts with SiSMPs, which can tolerate the volume change of SiSMPs and restrict the volume expansion of the laminates to a large degree, thus effectively maintaining the mechanical and electrical integrity of the electrode and significantly improving the electrochemical performance. As a result, SiSMPs with a 3D binder network exhibit high reversible capacity, superior rate capability and much prolonged cycle life. Additionally, the 3D alginate binder was also successfully applied for the industrial submicro-silicon waste from solar cell production. With all of the advantages, the innovative way to tolerate the severe volume change by using a high-strength polymeric network may open a new approach to realize the industrial application of Si-based anodes in lithium-ion batteries.

Porous ZnO–NiO composite micropolyhedrons have been successfully synthesized by calcination of mixed oxalate (Zn_0.9Ni_0.1(C₂O₄)₂·nH₂O) precursors in air. The oxalate precursor micropolyhedrons were synthesized by a mild chemical precipitation method without any template or surfactant, and found to have a relatively low decomposition temperature. We have successfully explored the application of the resulting porous ZnO–NiO composite micropolyhedrons as electrochemical capacitors. Electrochemical study shows that the obtained ZnO–NiO composites under different conditions have different electrochemical supercapacitor properties in 3.0 or 1.0 M KOH solutions. The porous ZnO–NiO micropolyhedron material (P1) obtained by calcination of the oxalate precursor at 400 °C has a large specific capacitance 649.0 F g⁻¹ in 3.0 M KOH solution and could maintain 99.1% of this value after 400 cycles at 5.8 A g⁻¹. Even at a high current density of 58.0 A g⁻¹, the specific capacitance of P1 is 395.2 F g⁻¹.