Growing environmental awareness and depleting fossil resources pose an emerging quest for lightweight materials with outstanding mechanical properties and economic production from sustainable resources that are biodegradable, carbon neutral, and safe. Super-strong yet lightweight anisotropic nanocellulose films are demonstrated by a cellulose DP protection strategy, exhibiting a tensile strength up to 1.13GPa. The high strength and low density of the nanocellulose films renders the highest specific strength of 820 MPa cm 3 g À1 among any known natural polymers and some strong metals.

Prussian blue (PB) and its analogues have been widely investigated as promising cathode materials for potassium ion batteries (PIBs) on account of their 3D open framework, which makes the intercalation/deintercalation of K+ ions easy and quick. However, the PB materials usually exhibit limited rate capacity and poor cycling performance, preventing their development and practical application. In this work, PB doped with nickel ions via a modified coprecipitation method was explored to improve the rate capacity and cycling performance of PIBs, and the effect of Ni doping on the materials’ performance was systematically studied. The optimal sample, 5% Ni-doped PB, delivered an enhanced discharge capacity of up to 135 mAh g–1, compared to 120 mAh g–1 with nondoped PB. Our optimal sample also displayed excellent cycling performance with 83.1% capacity retention after 300 cycles (0.1 A g–1) and declining just 0.0059% per cycle from 150 to 300 cycles. The discharge capacity at the high-voltage plateau increased from ∼40 up to 53 mAh g–1, offering a higher energy density for PIBs. On the basis of the characterization results, we ascribe the improved performance to the activation of nickel ions during the Fe2+C6/Fe3+C6 redox reaction.

The lithium ion re-intercalated into the LiMn2O4 lattice during self-discharge.

Versatile wood cellulose, the most prototypical abundant polymer on earth, is considered a promising natural material for the fabrication of biodegradable electronics. The development of biodegradable electronics may help alleviate the adverse environmental impact caused by the fast‐growing electronic waste (e‐waste). The focus of this review is to discuss recent major advances in biodegradable electronics with versatile wood cellulose in terms of supporting substrates and functional components. First, the biological biodegradation and structural hierarchy of versatile wood cellulose is briefly introduced, followed by highlighting three types of cellulose substrates (opaque and hazy cellulose paper, transparent and clear cellulose film, and transparent and hazy cellulose film) for biodegradable electronics. Then, recent progress and research achievements in the use of versatile wood cellulose with multiscale dimensions in biodegradable electronics as a functional component (e.g., advanced light management layer, high capacitance dielectric, and ionic conductor) or even smart materials (e.g., mechanochromic layer, humidity sensing layer, adaptable adhesive layer, and piezoelectric component) are summarized in detail. Finally, an overview of challenges and perspectives for biodegradable electronics with versatile cellulose is provided.