High mechanical ductility and high mechanical strength are important for materials including polymers. Current methods to increase the ductility of polymers such as plasticization always cause a remarkable drop in the ultimate tensile strength. There is no report on the ductilization of polymers that can notably increase the elongation at break while not lowering the ultimate tensile strength. Here, we report the salt-induced ductilization of an intrinsically conducting polymer, poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). Treating highly conductive PEDOT:PSS with a salt such as sodium perchlorate can enhance its elongation at break from 8.5 to 53.2%, whereas it hardly affects the tensile strength. Moreover, the resistance of the ductilized PEDOT:PSS films is insensitive to the tensile strain before fracture and slightly increases by only ~6% during the cyclic tensile testing with the strain up to 30%. These effects are ascribed to the decrease in the Coulomb attraction between PEDOT ⁺ and PSS ⁻ by the salt ions.

With the advancement of wearable and implantable health and medical electronics, biocompatible miniature energy storage devices were developed rapidly. In particular, biocompatible miniature supercapacitors (BMSCs) have the advantages of conventional supercapacitors, such as high-power density, fast charging/discharging rate, and long operating lifetime, as well as strong selectivity of biocompatible materials. They are expected to play an important role in personalized electronic integration systems. Biocompatibility involves the biosafety of materials and relates to the mechanics and geometrical forms. For example, BMSCs should be thin and compact, ensuring ease of portability and comfort for users. They should also be flexible and stretchable to conform to the skin or tissue, providing stable power to electronics even under deformation. Furthermore, biodegradability/ bioabsorbability ensures they are both body- and environment-friendly. This review summarizes the recent research progress of BMSCs as wearable and implantable energy storage devices, including the basic requirements and the selection of the components. Additionally, the advanced applications of BMSCs in multifunctional integration systems for real-time health monitoring and medical treatment are introduced, along with the associated challenges and prospects.

Addressing the spatial constraints inherent in wound therapy within narrow living organisms (e.g., intestinal tracts), the advancement of implantable micro-energy devices shows significant promise, which still faces the challenge of solving the trade-off between high energy and limited volume. Here we report a high-capacity implantable micro-supercapacitor based on the compact carbon nanotubes (CNTs) constricted by polyvinyl alcohol (PVA) framework, where the ionic conductive PVA network undergoes isotropic inward shrinkage, leading to bending deformation of CNTs and generating internal strain, thereby activating additional electrochemically active surface area. The electrochemically active surface area increases by 4000 times compared to its initial state, while the double-layer capacitance is 100 times higher than other reported carbon-based materials. Moreover, the implantable device has a small diameter of only 2.5 mm and provides sustained electrical stimulation exceeding 96 hours in simulated intestinal fluid, which is further verified in narrow intestinal sections across an experimental pig model with a 36% − 50% increase in healing rate compared to untreated wounds.

Asymmetric micro-supercapacitors (AMSCs) with a small size and high energy density can be compatible with portable and wearable electronic devices and are capable of providing stable, long-term power supply, attracting great research interest in recent years. Here, we present a simple and rapid preparation method for AMSCs’ fabrication. By regulating the hydrophilicity and hydrophobicity of coplanar laser-induced graphene (LIG) through the adjustment of the laser parameters, two electrode materials with distinct hydrophilic–hydrophobic properties were selectively deposited by sequentially dip-coating. The LIGs serve as current collectors, with activated carbon and poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) as active materials. After coating the electrolytes and folding the two electrodes, a high-performance AMSC was achieved. The device exhibits a high areal capacitance of 85.88 mF cm⁻² at a current density of 0.4 mA cm⁻², along with an impressive energy density of 11.93 µWh cm⁻² and a good rate performance. Moreover, it is demonstrated to be highly stable in 500,000 cycles. Two AMSCs in series can supply power to an electronic clock and birthday card. The method of preparing asymmetric electrodes in the same plane greatly facilitates the large-area preparation of AMSCs and series–parallel connection, providing an excellent idea for developing high-performance miniature energy storage devices.