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Homogeneously dispersed Sn nanoparticles approximately ⩽10 nm in a polymerized C (PC) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC anode consisting of 50 wt % Sn and 50 wt % PC, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g with a discharge capacity of 834.25 mAh g. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g at a high current density of 10 000 mA g, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g. Futhermore, a SPC-50 full-cell containing the LiCoO cathode exhibited a discharge capacity of 801.04 mAh g and an areal capacity of 1.57 mAh cm with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g.

A novel flexible fiber-shaped zinc–polyaniline battery (FZPB) is proposed to enhance the electrochemical performance, mass loading, and stability of polyaniline cathodes. To this end, electron-cyclotron-resonance oxygen plasma-modified carbon fibers are employed. During plasma treatment, on the carbon-fiber surface, O2 + plasma breaks the C–C, C–H, and C–N bonds to form C radicals, while the O2 molecules are broken down to reactive oxygen species (O+, O2+, O2 +, and O2 2+). The C radicals and the reactive oxygen species are combined to homogeneously form oxygen functional groups, such as −OH, −COOH, and −CO. The surface area and total pore volume of the treated carbon fibers increase as the plasma attacks. During electrodeposition, aniline interacts with the oxygen functional groups to form N–O and N–H bonds and π–π stacking, resulting in a homogeneous and high-loading polyaniline structure and improved adhesion between polyaniline and carbon fibers. In an FZPB, the cathode with plasma-treated carbon fibers and a polyaniline loading of 0.158 mg mgCF –1 (i.e., 2.36 mg cmCF –1) exhibits a capacity retention of 95.39% after 200 cycles at 100 mA g–1 and a discharge capacity of 83.96 mA h g–1 at such a high current density of 2000 mA g–1, which are ∼1.67 and 1.24 times those of the pristine carbon-fiber-based one, respectively. Furthermore, the FZPB exhibits high flexibility with a capacity retention of 86.4% after bending to a radius of 2.5 mm for 100 cycles as a wearable energy device.