A dynamic stability design strategy for lithium metal solid state batteries.

A solid-state electrolyte is expected to suppress lithium (Li) dendrite penetration with high mechanical strength. However, in practice it still remains challenging to realise a lithium metal anode for batteries, because micrometre- or submicrometre-sized cracks in ceramic pellets can frequently be generated during battery assembly or long-time cycling. Once cracks form, lithium dendrite penetration is inevitable. Here we describe a solid-state battery design with a hierarchy of interface stabilities (to lithium metal responses), to achieve an ultrahigh current density with no lithium dendrite penetration. Our multilayer design has the structure of a less-stable electrolyte sandwiched between more-stable solid electrolytes, which prevents any lithium dendrite growth through well localized decompositions in the less stable electrolyte layer. A mechanism analogous to the expansion screw effect is proposed, whereby any cracks are filled by dynamically generated decompositions that are also well constrained, probably by the 'anchoring' effect the decompositions induce. The cycling performance of the lithium metal anode paired with a LiNiMnCoO cathode is very stable, with an 82 per cent capacity retention after 10,000 cycles at a 20C rate (8.6 milliamps per centimetre squared) and 81.3 per cent capacity retention after 2,000 cycles at a 1.5C rate (0.64 milliamps per centimetre squared). Our design also enables a specific power of 110.6 kilowatts per kilogram and specific energy up to 631.1 watt hours per kilogram at the micrometre-sized cathode material level.