Dendrites are a bit like the tin-whiskers that plague engineers ever since the EU passed those laws requiring the use of tin/silver solder instead of the much better tin/lead solder...grrrrr
An electrolyte from wood is an unexpected turn...
The holy-grail of battery tech is development of a super-capacitor that can replace the batteries we use now.. a suitable supercap would last pretty much forever, be lightweight, charge almost instantly and hold an enormous load of electrons... you can charge a supercap so quickly that you must limit the inrush current or your power supply/charger will fail.
I have worked with small supercaps, mostly while investigating their use for implanted bio-medical devices that can be recharged using a simple method almost exactly like the wireless chargers for cellphones.
If this is a true solution to the dendrite problem (which I first became aware of circa 1973) I will be very surprised. I hope it is... this is a persistent material science conundrum.