Anatase TiO2 nanocrystals were successfully employed as anodes for rechargeable Na-ion batteries for the first time. The mesoporous electrodes exhibited a highly stable reversible charge storage capacity of ~150 mA h g(-1) over 100 cycles, and were able to withstand high rate cycling, fully recovering this capacity after being cycled at rates as high as 2 A g(-1).

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Thanks to low costs and the abundance of the resources, sodium‐ion (SIBs) and potassium‐ion batteries (PIBs) have emerged as leading candidates for next‐generation energy storage devices. So far, only few materials can serve as the host for both Na+ and K+ ions. Herein, a cubic phase CuSe with crystal‐pillar‐like morphology (CPL‐CuSe) assembled by the nanosheets are synthesized and its dual functionality in SIBs and PIBs is comprehensively studied. The electrochemical measurements demonstrate that CPL‐CuSe enables fast Na+ and K+ storage as well as the sufficiently long duration. Specifically, the anode delivers a specific capacity of 295 mA h g−1 at current density of 10 A g−1 in SIBs, while 280 mA h g−1 at 5 A g−1 in PIBs, as well as the high capacity retention of nearly 100% over 1200 cycles and 340 cycles, respectively. Remarkably, CPL‐CuSe exhibits a high initial coulombic efficiency of 91.0% (SIBs) and 92.4% (PIBs), superior to most existing selenide anodes. A combination of in situ X‐ray diffraction and ex situ transmission electron microscopy tests fundamentally reveal the structural transition and phase evolution of CuSe, which shows a reversible conversion reaction for both cells, while the intermediate products are different due to the sluggish K+ insertion reaction.

Inspired by traditional cyanotype, we first design a novel strategy for the fabrication of low-cost, lightweight, and soft patterned electrodes. When employed in flexible potassium-ion battery, the patterned electrodes show superior electrochemical performance, including good cycling stability and high energy density. This appealing photographic printing technique as well as the promising electrochemical results opens a new avenue for the fabrication of flexible energy storage systems.