Spent batteries are conventionally treated with extreme heat (over 500°C) to smelt valuable metals, which emits hazardous toxic gases. Or they use strong acid solutions applied to a crushed "mess" of battery waste.
A group of Singaporean scientists however, have found a 3rd option using orange peels, which successfully extracted around 90% of cobalt, lithium, nickel, & manganese from spent lithium-ion batteries – a comparable efficacy to the approach using hydrogen peroxide applied to crushed battery waste.