Circular economy, in simple words means, reusing old materials back into new products again and again.
From the point of view of circular economy, there no thing such as "waste", rather everything is a "resource". Circular economy advocates for reuse of materials and thus reducing dependency on finite natural resources and materials.
In case of batteries, circular economy means extracting valuable materials from the batteries, such as metals, plastics, electrolytes etc. and using it back to make new batteries or other products.
This allows reduction in emission of greenhouse gases caused during mining and manufacturing. Circular economy enables sustainability of resources and materials.