I have had the opportunity to be involved with one of the national labs regarding battery technology. Batteries continue to make progress, but the energy density necessary for using batteries in aviation in a practical manner is still a very long way out (yes, very different than ground based transport but still germane to the subject). The issue I have with batteries is how they are promoted. Most do not consider the impact from womb to tomb. If they did, hydrocarbon fuels would fare far better if those promoting batteries were honest.
On another note, hydrogen as fuel has been brought up many times. The difficulty with hydrogen is how it is stored. As a gas, it takes up a LOT of space - even under high pressure. Though the energy density may be high, the physical density is not. If it is cooled to reduce the physical density, the energy required to keep it cool makes it much less efficient. Additionally, taking the argument of greenhouse gases into consideration, the by-product of hydrogen is water vapor which is a larger contributor to the greenhouse effect than CO2. The reality with hydrogen is that there is already a very natural, efficient and effective way to store hydrogen: combine it with carbon, as in hydrocarbons. I'm all for hydrogen in that configuration as it makes a LOT of sense.
Bottom line is batteries sound better than they may actually be when the entire process it taken fully into consideration. The materials required by batteries is enormous, even considering the recycling and recovery of those materials from spent batteries. It seems much of this is ignored by many. I'm all for more environmentally responsible energy. I just want comprehensiveness and complete honesty in the evaluation process. I believe we are far from that at the moment.