## 1 Introduction  
Electdeposition is a non-spontaneous electrochemical phenomenon where charged ions in an electrolyte migrate under the influence of an electromotive force (electric field) towards a substrate, typically the cathode. However, spontaneous deposition (cementation) of a metal can also occur when more noble metal ions interact with substrates composed of a less noble metal [1, 2]. At the cathode, these ions undergo a reduction reaction, transferring electrons and losing their ionic charge, which allows them to deposit as a solid metallic layer. This process is fundamental to many electrochemical systems, including batteries, fuel cells, and electroplating [3]. However, electrodeposition in these systems serves dissimilar roles. In batteries and fuel cells, the deposition of materials on electrodes is often an undesired byproduct, as it can lead to performance degradation, for instance dendrite formation or electrode passivation [4, 5]. In the context of this review, electrodeposition refers to the general process of metal deposition through the electrochemical process. Furthermore, electroplating refers to a subset of electrodeposition that uses the same principles to achieve controlled deposition of metal onto a substrate, aiming to enhance surface properties like corrosion resistance, durability, and aesthetic appeal [4; 5]. Electroplating has a history dating back over two centuries, originating in the early 1800s when gold was first deposited onto silver using [PERSON]'s voltaic pile in 1805 [6]. Although this work was initially suppressed, the process was reinvented in the 1830s and gained industrial traction by the 1840s, when the use of cyanide-based gold and silver plating solutions were patented in the United Kingdom [7]. The technique soon expanded to copper, nickel, and zinc, and by the late 19 th century, it was widely used for decorative and corrosion-resistant applications. Electroplating became essential in the manufacture of coins, jewelry, and metal tableware, establishing itself as a critical process in emerging industrial economies [8]. Throughout the 20 th century, electroplating matured into a cornerstone of modern manufacturing and the advent of modern electroplating began in 1916 with the publication of [PERSON]'s paper [9]. The electrolyte formulated by [PERSON] greatly improved previous solutions by increasing efficiency, throwing power, and deposition rate [10]. Variations in the Watts bath formulation are still the most used electroplating solutions in the world. Other major advances included the introduction of electroless plating in 1946 [11], allowing metal deposition on non-conductive substrates. Post-war industrial demand drove innovation in alloy and multilayer coatings, pulse plating, and environmental improvements such as the replacement of cyanide with sulfate-based electrolytes [12]. Applications of electroplating now spans from automotive and aerospace components to electronics and biomedical devices, and recent developments, such as the use of ionic liquids and nanostructured deposits, continue to expand its relevance in high-performance and sustainable materials engineering [13; 14]. As of 2022, over 150,000 tons of nickel were electrodeposited annually, which is five percent of the total annual nickel production [15]. While electrodeposition onto metallic substrates is widely practiced, the electroplating of metals onto non-metallic surfaces, particularly polymers, presents unique challenges and opportunities. Electroplating nickel onto polymers is arduous because chemically aggressive plating solutions can swell, crack, or degrade the polymer surface, especially during multistep treatments. Additionally, achieving uniform deposition thickness on complex polymer geometries is difficult, as trapped solutions and irregular surfaces can cause uneven deposits, voids, or dimensional inaccuracies in the plated part.