The ever-increasing energy density of the Li-ion battery calls for utilization of high-capacity cathodes and anodes, which tend to be more reactive and thus bring serious safety concern. Under such context, the solid-state Li battery becomes a hotspot because of its potential in the breakthrough of energy density as well as the avoidance of uncontrollable chemical reactions. Recently, many review and perspective papers appear, addressing the urgency of improving solid-electrolytes' ionic conductivity and constructing stable conductive interfaces between electrolyte and electrode with respect to available electrolytes, including polymers, nitrides, sulfides, and oxides. Nevertheless, each type of electrolyte has its own distinctive problems, which is worthwhile specifically elaborating in order to find effective solutions. Therefore, here, we present our viewpoints on the key issues related to the garnet electrolytes and relevant batteries, which have not ever been dedicatedly addressed previously. On the basis of our recent progress, together with others reported in the literature, we expect that the solid garnet batteries are promising for application if the best use is made of garnet advantages and disadvantages are bypassed.

A high-performance electrochromic-energy storage device (EESD) is developed, which successfully realizes the multifunctional combination of electrochromism and energy storage by constructing tungsten trioxide monohydrate (WO·HO) nanosheets and Prussian white (PW) film as asymmetric electrodes. The EESD presents excellent electrochromic properties of broad optical modulation (61.7%), ultrafast response speed (1.84/1.95 s), and great coloration efficiency (139.4 cm C). In particular, remarkable cyclic stability (sustaining 82.5% of its initial optical modulation after 2500 cycles as an electrochromic device, almost fully maintaining its capacitance after 1000 cycles as an energy storage device) is achieved. The EESD is also able to visually detect the energy storage level via reversible and fast color changes. Moreover, the EESD can be combined with commercial solar cells to constitute an intelligent operating system in the architectures, which would realize the adjustment of indoor sunlight and the improvement of physical comfort totally by the rational utilization of solar energy without additional electricity. Besides, a scaled-up EESD (10 × 11 cm) is further fabricated as a prototype. Such promising EESD shows huge potential in practically serving as electrochromic smart windows and energy storage devices.

A comprehensive and systematic summary of the current developments of BC in electrochemical energy storage and conversion.