Li-ion batteries are starting to near their performance ceiling and performance improvements are proving increasingly difficult to come by. Trade-offs are having to be made to increase energy density with the use of high nickel cathodes and high capacity anodes are plagued by safety and cycle life problems. Delving into the trends being seen in patent applications can provide insight into the key areas of innovation in Li-ion batteries and the areas of development favoured by key players, helping to provide insight into how Li-ion technology can continue to improve. The growth in and subject of patent activity mirrors in many ways what is happening in the wider Li-ion industry. Certainly, competition between battery manufacturers is intensifying and emphasises the importance of battery R&D and protecting innovation.