Zinc (Zn) metal is considered the promising anode for "post-lithium" energy storage due to its high volumetric capacity, low redox potential, abundant reserve, and low cost. However, extravagant Zn is required in present Zn batteries, featuring low Zn utilization rate and devicescale energy/power densities far below theoretical values. The limited reversibility of Zn metal is attributed to the spontaneous parasitic reactions of Zn with aqueous electrolytes, that is, corrosion with water, passive by-product formation, and dendrite growth. Here, a new ionselective polymer glue coated on Zn anode is designed, isolating the Zn anode from the electrolyte by blocking water diffusion while allowing rapid Zn 2+ ion migration and facilitating uniform electrodeposition. Hence, a record-high Zn utilization of 90% is realized for 1000 h at high current densities, in sharp contrast to much poorer cyclability (usually < 200 h) at lower Zn utilization (50-85%) reported to date. When matched with the vanadium-based cathode, the resulting Zn-ion battery exhibited an ultrahigh device-scale energy density of 228 Wh kg −1 , comparable to commercial lithium-ion batteries.

To develop wearable and implantable bioelectronics accommodating the dynamic and uneven biological tissues and reducing undesired immune responses, it is critical to adopt batteries with matched mechanical properties with tissues as power sources. However, the batteries available cannot reach the softness of tissues due to the high Young's moduli of components (e.g., metals, carbon materials, conductive polymers, or composite materials). The fabrication of tissue‐like soft batteries thus remains a challenge. Here, the first ultrasoft batteries totally based on hydrogels are reported. The ultrasoft batteries exhibit Young's moduli of 80 kPa, perfectly matching skin and organs (e.g., heart). The high specific capacities of 82 mAh g−1 in all‐hydrogel lithium‐ion batteries and 370 mAh g−1 in all‐hydrogel zinc‐ion batteries at a current density of 0.5 A g−1 are achieved. Both high stability and biocompatibility of the all‐hydrogel batteries have been demonstrated upon the applications of wearable and implantable. This work illuminates a pathway for designing power sources for wearable and implantable electronics with matched mechanical properties.

LiÀ CO 2 batteries are explored as promising power systems to alleviate environmental issues and to implement space applications. However, sluggish cathode kinetics of CO 2 reduction/evolution result in low round-trip efficiency and poor cycling stability of the fabricated energy-storage devices. Herein, we design a heterostructued photocathode comprising carbon nanotube and carbon nitride to accelerate cathode reactions of a LiÀ CO 2 battery under illumination. Benefiting from the unique defective structure of carbon nitride and favorable interfacial charge transfer, the photocathode effectively harvests ultraviolet-visible light to generate abundant photoexcited carriers and coordinates energetic photoelectrons/holes to participate in the discharge/charge reactions, leading to efficient photo-energy utilization in decreasing reaction barriers and enhancing thermodynamic reversibility of LiÀ CO 2 battery. The resulting battery delivers a high round-trip efficiency of 98.8 % (ultralow voltage hysteresis of 0.04 V) and superior cycling stability (86.1 % efficiency retention after 100 cycles).