A Biodegradable Secondary Battery and its Biodegradation Mechanism for Eco‐Friendly Energy‐Storage Systems

Abstract The production of rechargeable batteries is rapidly expanding, and there are going to be new challenges in the near future about how the potential environmental impact caused by the disposal of the large volume of the used batteries can be minimized. Herein, a novel strategy is proposed to address these concerns by applying biodegradable device technology. An eco‐friendly and biodegradable sodium‐ion secondary battery (SIB) is developed through extensive material screening followed by the synthesis of biodegradable electrodes and their seamless assembly with an unconventional biodegradable separator, electrolyte, and package. Each battery component decomposes in nature into non‐toxic compounds or elements via hydrolysis and/or fungal degradation, with all of the biodegradation products naturally abundant and eco‐friendly. Detailed biodegradation mechanisms and toxicity influence of each component on living organisms are determined. In addition, this new SIB delivers performance comparable to that of conventional non‐degradable SIBs. The strategy and findings suggest a novel eco‐friendly biodegradable paradigm for large‐scale rechargeable battery systems.