Microgrids consist of multiple parallel-connected distributed generation (DG) units with coordinated control strategies, which are able to operate in both grid-connected and islanded mode. Microgrids are attracting more and more attention since they can alleviate the stress of main transmission systems, reduce feeder losses, and improve system power quality. When the islanded microgrids are concerned, it is important to maintain system stability and achieve load power sharing among the multiple parallel-connected DG units. However, the poor active and reactive power sharing problems due to the influence of impedance mismatch of the DG feeders and the different ratings of the DG units are inevitable when the conventional droop control scheme is adopted. Therefore, the adaptive/improved droop control, network-based control methods and cost-based droop schemes are compared and summarized in this paper for active power sharing. Moreover, nonlinear and unbalanced loads could further affect the reactive power sharing when regulating the active power, and it is difficult to share the reactive power accurately only by using the enhanced virtual impedance method. Therefore, the hierarchical control strategies are utilized as supplements of the conventional droop controls and virtual impedance methods. The improved hierarchical control approaches such as the algorithms based on graph theory, multi-agent system, the gain scheduling method and predictive control have been proposed to achieve proper reactive power sharing for islanded microgrids and eliminate the effect of the communication delays on hierarchical control. Finally, the future research trends on islanded microgrids are also discussed in this paper.

Solid‐state lithium batteries have aroused wide interest with the probability to guarantee safety and high energy density at the same time. In the past decade, fruitful endeavors have been devoted to promoting each component of these batteries, including solid electrolyte with high conductivity, dendrite‐free lithium anode, and high‐capacity cathode. However, the currently achieved cell performances are still inconsistent with the original expectations, in which interfaces severely hamper the energy output and cycling stability for practical application. Herein, particular attentions are paid to the interface between cathode and solid electrolyte. The huge resistance caused at this interface can be found throughout the entire life of batteries from preparation to operation. Accordingly, these issues are divided into physical contact, thermal interdiffusion, space‐charge layer, electrochemomechanical breakdown, and undesirable side reactions and further elucidated in detail. Moreover, representative developments concerning the cathode/solid electrolyte interface in terms of compositional and morphological control in cathode, architecture and manufacture design in solid electrolyte, and artificial interphase building are summarized. With these efforts, the emphasis of the fundamental issues and perspectives of interface between cathode and solid electrolyte may eventually contribute to high‐energy long‐cycling solid‐state lithium batteries.

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