Primer coatings enhance the separation of cathode active materials from lithium-ion battery cathode sheets during direct electrical pulsed discharge

The effects of primer coatings on the separation of cathode active materials (CAMs) from lithium-ion battery cathode sheets using the direct electrical pulse method were investigated. Three cathode sheet types were examined: no primer coating, primer coating A, and primer coating B. Delamination behavior, microstructure, and elemental composition were analyzed by high-speed video imaging, scanning electron microscopy, and microscopic Fourier-transform infrared spectroscopy. Heat conduction simulations revealed a temperature rise during electrical pulsed discharge. Results showed that the delamination rate and mechanism varied depending on the presence and type of primer coating. With no primer coating, a high delamination rate (98.9%) was achieved, requiring higher energy input and ultimately fragmenting the Al foil. With primer coating A, the delamination rate was 93.2%, occurring between the primer coating and CAMs layer. With primer coating B, a 100% delamination rate was achieved, occurring between the Al foil and primer coating while retaining the Al foil shape and maintaining a high rate across a wide range of conditions at a lower energy input. The delamination mechanism is attributed to adhesive deactivation due to Joule heating, expansion from plasma formation, horizontal thermal stress due to differences in thermal expansion coefficients, and bending thermal stress from temperature gradients within layers. The low thermal resistance and conductivity of adhesives induce deactivation and thermal stress, enabling effective delamination by electrical pulsed discharge. This study provides insights into primer coatings that enhance battery performance while facilitating post-use material separation, thus promoting the development of high-performance recyclable batteries.