You may also be interested in aluminum-air batteries, which have better than 10 times the specific energy density compared to lithium ion chemistries. The down

You may also be interested in aluminum-air batteries, which have better than 10 times the specific energy density compared to lithium ion chemistries. The downside is that they aren't rechargable, but that may not matter for flights (they are recyclable though). https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery