Lithium‐ion batteries (LIBs) have significantly impacted the daily lives, finding broad applications in various industries such as consumer electronics, electric vehicles, medical devices, aerospace, and power tools. However, they still face issues (i.e., safety due to dendrite propagation, manufacturing cost, random porosities, and basic & planar geometries) that hinder their widespread applications as the demand for LIBs rapidly increases in all sectors due to their high energy and power density values compared to other batteries. Additive manufacturing (AM) is a promising technique for creating precise and programmable structures in energy storage devices. This review first summarizes light, filament, powder, and jetting‐based 3D printing methods with the status on current trends and limitations for each AM technology. The paper also delves into 3D printing‐enabled electrodes (both anodes and cathodes) and solid‐state electrolytes for LIBs, emphasizing the current state‐of‐the‐art materials, manufacturing methods, and properties/performance. Additionally, the current challenges in the AM for electrochemical energy storage (EES) applications, including limited materials, low processing precision, codesign/comanufacturing concepts for complete battery printing, machine learning (ML)/artificial intelligence (AI) for processing optimization and data analysis, environmental risks, and the potential of 4D printing in advanced battery applications, are also presented.

A waste heat recovery unit can transfer heat at high temperatures to another energy form for specific purposes with increasing energy efficiency. The heat recovered from nature or human body systems for generating electricity or powering wearable devices is a good example of green and sustainable power sources. Currently available thermoelectric generators (TEGs) can convert heat into electricity. However, they lack mechanical flexibility and specially designed structures to efficiently harvest energy from low temperature (≤100 °C) surfaces, e.g., hot water pipes, car roofs, or human skin. Here, we report bottom-up manufacturing that scaled up molecular-level polymer-nanoparticle hybridization to device-level units, thus bridging nanoscale material interactions to macroscale energy conversion efficiency. In situ polymerization optimized the interface between polyaniline (PANi) and multi-walled carbon nanotubes (MWNTs) to reach a higher power factor (i.e., ∼1.25 μW m⁻¹ K⁻²) than the directly mixed PANi/MWNT samples (i.e., ∼0.8 μW m⁻¹ K⁻²), both with a high nanotube concentration of 58.7 wt%. With a rapidly prototyped thermoplastic polyurethane (TPU) substrate, the PANi/MWNT hybrids formed a bio-inspired, gill-mimicking, and flexible thermoelectric generator (fTEG). These out-of-plane structures with PANi/MWNTs as gills showed highly efficient energy transformation on the surfaces of hot water containers (∼100 °C), car roofs (∼38 °C), and human skin (∼37 °C). The PANi/MWNT fTEG showed excellent mechanical durability with improved stiffness and strength than pure PANi, fatigue resistance, and bendability most appropriate for powering wearable sensors. With a strain switch, the fTEG is able to power a sensing system that reveals biosignals, such as joint movement and respiration, in the long term. The self-powered sensing system applies to wearable smart devices and demonstrates the potential for using the thermoelectric effect as an alternative power source.