Paper-based batteries present a sustainable and biodegradable alternative to traditional energy storage systems by using cellulose-based electrodes and water-based processing. These eco-friendly batteries are ideal for single-use electronics such as biosensors, environmental monitors, and smart packaging. Their flexible form factor and compostable materials make them suitable for disposable applications in clean environments, logistics, and low-power wearable devices. Different formats include zinc-based, lithium-ion, microbial, and supercapacitor variants, with hybrid systems integrating nanomaterials for enhanced performance. These batteries exemplify circular design principles, supporting waste valorization, green energy, and reduced reliance on toxic components.