One is sodium-ion batteries, which are a popular alternative to the lithium-based cells used in EVs and grid storage installations. Sodium-ion batteries don’t require the kinds of critical minerals lithium-ion batteries do, which can be both expensive and tied up by geopolitics. One major stumbling block for sodium-ion batteries is their energy density. That limits the total energy density of the battery, so it’s a problem for applications like electric vehicles, where a low energy density would restrict range. In January, his team published research describing a process to make ammonia underground, using naturally-occurring heat and pressure to drive the necessary chemical reactions.