Challenges in speeding up solid-state battery development

Recent worldwide efforts to establish solid-state batteries as a potentially safe and stable high-energy and high-rate electrochemical storage technology still face issues with long-term performance, specific power and economic viability. Here, we review key challenges that still involve the need for fast-conducting solid electrolytes to provide sufficient transport in composite cathodes. In addition, we show that high-performance anodes together with protection concepts are paramount to establish dense high-energy solid-state batteries and that lithium-based solid-state batteries as well as metal anodes may not be the ultimate solution. We further discuss that diversity in terms of materials, research teams and approaches is key to establish long-term solid-state batteries. About ten years after the first ground-breaking publication of lithium solid electrolytes with an ionic conductivity higher than that of liquid electrolytes, it is time to realistically address the remaining key challenges for full-scale commercialization, cell performance and implementation.