and power the building in the night. [12] Such a smart combination not only provides multifunctions, but also saves materials and footprint in modern buildings. Another example is the wireless operation devices such as unmanned aerial vehicles and implantable biosensors, which are required to be placed in remote area or hazardous condition. They are required to be self-charged/powered by converting other energy forms from natural sources (such as heat, solar, and wind) or human movements (via piezoelectric and triboelectric effects) into usable power sources. [16][17][18][19][20] Moreover, the harvested energy needs to be stored electrochemically for backup power. [21][22][23] In this context, multifunctional devices/materials with multiple roles are imperative for the development of future self-powered smart devices.Electrochemical energy storage (EES) system is one of the most important parts in integrated smart devices. [24][25][26][27][28][29][30][31][32][33] The current dominant EES systems include lithium-ion batteries (LIBs) and supercapacitors. [34][35][36][37] The former generally possess high energy density but with relatively low power density, [38][39][40] whereas the latter have the opposite advantage and are typically used for high-power area. [41][42][43][44][45][46] In general, current EES devices require external power source and intensive maintenance. This can be challenging in deserts or other uninhabited areas. In this regard, it becomes quite relevant to develop self-powered smart devices by integrating energy harvest and conversion and storage units. [47] Currently, considerable efforts are being devoted to fabricating integrated/joint systems to combine energy harvesting/ storage components. The harvesting component can capture the energy from surroundings and convert into usable energy to power electrical devices. [28,48,49] For example, Wang and coworkers fabricated a series of self-powered devices (electrochromic devices, water splitting systems, and sensors) driven by piezoelectric nanogenerators and triboelectric nanogenerators. [50][51][52][53][54] Such nanogenerators convert the small magnitude of mechanical energy in our living environment into electricity. In addition, solar cells have also been integrated into electrochromic devices to achieve self-powered operation and to maximize energy saving/utilization. [55,56] Along with multifunction, attentions are also being paid to miniaturized energy systems such as nanosized and fibershaped energy conversion/storage devices. [57][58][59][60][61] Though planar-structured devices have the advantage of simple process and cost effectiveness, they cannot be easily integrated with wearable equipment. Hence, developing new materials that are flexible and stretchable, transparent and conductive, or Multifunctional energy devices with various energy forms in different operation modes are under current research focus toward the new-generation smart and self-powered electronics. In this review, the recent progress made in developing integrated/jo...