Introduction to the special issue in honour of Prof. John Kilner's 75th birthday

The special issue of Journal of Materials Chemistry A celebrates the achievements of Professor John Kilner on the occasion of his 75th birthday. John is a materials scientist whose broad interests span the physical sciences with a focus on energy materials and the use of advanced ion beam techniques to understand key transport processes in such systems. John began his career with a degree in physics from the University of Birmingham, before completing his PhD in Metallurgy at the same institution under the supervision of Professor Rex Harris. Throughout his career John has been highly collaborative, welcoming numerous visiting researchers to his group, many of whom have gone on to be longstanding collaborators and international leaders in their fields.