Charge retention refers to the ability of energy storage devices, like batteries and capacitors, to hold onto their stored energy over time. It's a crucial aspect for applications requiring long-term reliability, such as emergency backup systems, remote sensors, and electric vehicles. Factors influencing charge retention include the device's chemistry, temperature, and age. For instance, lithium-ion batteries are favored in many applications for their excellent charge retention compared to other types. Improving charge retention is a key focus in battery research, aiming to enhance the efficiency and lifespan of energy storage solutions.