Toward high‐temperature lithium‐ion batteries, adding inorganic materials are proposed as an effective strategy. However, inorganic particles tend to aggregate in the polymer matrix, causing degradation in battery performance. Here, a PVDF‐HFP/colloidal Al2O3 composite separator is prepared with a phase inverse method. The colloidal Al2O3 particles well dispersed in the PVDF‐HFP polymer matrix substantially enhance the mechanical strength of the PVDF‐HFP separator. The PVDF‐HFP/colloidal Al2O3 composite separator owns a high electrolyte uptake of 372%, a high ionic conductivity of 1.3 × 10−3 S cm−1 at 80 °C and delivers high capacity retention of 95.6% after 100 charge–discharge cycles at 0.5 C. In addition, PVDF‐HFP/colloidal Al2O3 separator only has a 4.5% thermal shrinkage at 150 °C and exhibits high electrochemical performances upon annealing at 140 °C.

As anodes of Li-ion batteries, copper oxides (CuO) have a high theoretical specific capacity (674 mA h g ) but own poor cyclic stability owing to the large volume expansion and low conductivity in charges/discharges. Incorporating reduced graphene oxide (rGO) into CuO anodes with conventional methods fails to build robust interaction between rGO and CuO to efficiently improve the overall anode performance. Here, Cu O/CuO/reduced graphene oxides (Cu O/CuO/rGO) with a 3D hierarchical nanostructure are synthesized with a facile, single-step hydrothermal method. The Cu O/CuO/rGO anode exhibits remarkable cyclic and high-rate performances, and particularly the anode with 25 wt% rGO owns the best performance among all samples, delivering a record capacity of 550 mA h g at 0.5 C after 100 cycles. The pronounced performances are attributed to the highly efficient charge transfer in CuO nanosheets encapsulated in rGO network and the mitigated volume expansion of the anode owing to its robust 3D hierarchical nanostructure.

A PVDF-HFP/colloidal-TiO 2 composite separator is synthesized for high-temperature lithium-ion batteries. Incorporation of colloidal TiO 2 in the PVDF-HFP matrix forms a highly-uniform composite micro-structure with strong adsorption interactions between TiO 2 and PVDF-HFP due to the presence of citric acid. The strong interactions are giving rise to advantageous mechanical robustness, separator/electrode interface and electrolyte uptake. The separator shows remarkable stability upon thermal treatment at 150 8C. With a high ionic conductivity up to 1.57 10 À3 S cm À1 , the LFP/Li cell with PVDF-HFP/colloidal-TiO 2 composite separator delivers charge-discharge capacities of 156.95 mAh g À1 (0.1 C) at room temperature and 120.8 mAh g À1 (0.5 C) after annealing cells at 140 8C for 3 hours with a 99 % capacity retention after 100 cycles. The PVDF-HFP/colloidal-TiO 2 separator demonstrates promising potentials for practical applications in high-temperature environments.

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Supercapacitors have gained e wide attention because of high power density, fast charging and discharging, as well as good cycle performance. Recently, expanded graphite (EG) has been widely investigated as an effective electrode material for supercapacitors owing to its excellent physical, chemical, electrical, and mechanical properties. Based on charge storage mechanism, supercapacitors have been divided into symmetric, asymmetric, and hybrid supercapacitors. Here, we review the study progress of EG-based materials to be electrode materials. Furthermore, we discuss the application prospects and challenges of EG-based materials in supercapacitors.