New generation of lithium-ion batteries (LIBs) integrating solar energy conversion and storage is emerging, as they could solve the fluctuation problem in the utilization of solar energy. Photo-rechargeable lithium-ion batteries (PR-LIBs) are ideal devices for such target, in which solar energy is converted into electricity and stored in LIB. In order to achieve the high performance of PR-LIB, it is crucial to develop dual-function electrode materials that can synergistically capture solar energy and store lithium. Herein, we present photo-rechargeable lithium-ion batteries using defective black TiO₂ as photoanode prepared by lithium reduction. The photoanode exhibits excellent photo response in full solar spectrum with a capacity enhancement of 46.4% under illumination, corresponding to the energy conversion efficiency of 4.4% at the current density of 1 A·g⁻¹. When illumination is applied at 20 mA·g⁻¹, the battery capacity increases from ~ 230 in dark to ~ 349 mAh·g⁻¹ at the first cycle, and then stabilizes at 310 mAh·g⁻¹, approaching the theoretical value of 335 mAh·g⁻¹ of TiO₂ electrode material. This finding provides thoughts for breaking the capacity limitations in TiO₂ and paves the way for powering LIBs by solar illumination.

Elasticity, as an emerging phenomenon of crystals, endows the newfangled properties on crystals owing to the altered local crystallinity in the deformed state, and hence attracts increasing research endeavors. However, only a few molecular crystals and a limited number of one-dimensional coordination polymer crystals have exhibited such fantastic elastic response under mechanical stress. Herein, we report the first example of elastic hydrogen-bonded ionic framework (HIF) of {(CN₃H₆)₂[Ti(μ₂-O)(SO₄)₂]}_n, assembled from one-dimensional negatively charged inorganic [Ti(μ₂-O)(SO₄)₂]_n²ⁿ⁻ chains and positively charged organic guanidinium cations via hydrogen bonds and electrostatic interactions. The slender prismatic single crystal exhibits remarkable elasticity with an optimal elastic bending strain (ε) of 2.5%. Impressively, the crystals give rise to two-dimensional elasticity owing to the equivalent crystallographic planes of the exposed faces and an unusual elastic response at liquid nitrogen temperature. The in-depth crystallographic analyses reveal hydrogen bonds and electrostatic interactions between anion chains and cations function like adhesive glue and account for such specific elastic properties, owing to the flexible and dynamic attributes of hydrogen bonds as they can work in a range of distance and orientation. And the channel in HIF provides space for bending with reduced strain. Incorporating these factors into low-dimensional crystals could be a general guidance for designing elastic crystals. Elasticity ganged with other intrinsic properties of HIF materials could inspire their newfangled applications in the near future.

Polyoxometalates (POMs) with multiple redox active sites have been reported as charge sponge for lithium-ion batteries (LIBs). Herein, we for the first time introduce a polyoxovanadate (POV) ionic crystals with macrocations, [Ni(Phen)₃][ClV₁₄O₃₄]Cl (NiV₁₄, Phen = 1,10-phenanthroline), as an anode material for LIBs. The existence of macrocation [Ni(Phen)₃]²⁺ stabilizes the open tunnels inside NiV₁₄. The NiV₁₄ electrode exhibits superior rate capabilities (1083 mAh·g⁻¹ at 100 mA·g⁻¹ and 384 mAh·g⁻¹ at 2000 mA·g⁻¹) due to the rapid capacitive dominated contribution and high Li⁺ ions diffusion coefficients (3.3 × 10⁻¹² cm⁻²·s⁻¹), and it delivers a remarkable cycling stability with a Coulombic efficiency of 99.7% after 1000 cycles at 2000 mA·g⁻¹. Such performance can be attributed to the stable structure of NiV₁₄ and the highly reversible valence changes of vanadium during the charge/discharge processes, which are revealed by a combination of in situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine structure (XAFS) measurements. This work not only demonstrates that NiV₁₄ with open tunnels stabilized by macrocation is a promising anode material for high performance LIBs, but also provides important references for the rational design of POMs electrode materials in advanced energy storage systems.

Polymeric carbon nitride (CN) as a metal-free photocatalyst holds great promise to produce high-value chemicals and H₂ fuel utilizing clean solar energy. However, the wider deployment of pristine CN is critically hampered by the poor charge carrier transport and high recombination. Herein, we develop a facile salt template-assisted interfacial polymerization strategy that in-situ introduces alkali ions (Na⁺, K⁺) and nitrogen defects in CN (denoted as v-CN-KNa) to simultaneously promote charge separation and transportation and steer photoexcited holes and electrons to their oxidation and reduction sites. The photocatalyst exhibits an impressive photocatalytic H₂ evolution rate of 8641.5 μmol·g⁻¹·h⁻¹ (33-fold higher than pristine CN) and also works readily in real seawater (10752.0 μmol·g⁻¹·h⁻¹) with a high apparent quantum efficiency up to 18.5% at 420 nm. In addition, we further demonstrate that the v-CN-KNa can simultaneously produce H₂ and N-benzylidenebenzylamine without using any other sacrificial reagent. In situ characterizations and DFT calculations reveal that the alkali ions notably promote charge transport, while the nitrogen defects generate abundant edge active sites, which further contribute to efficient electron excitation to trigger photoredox reactions.