Natural electrolyte drinks.

I know the OP is only asking about electrolytes but +1 for hi-juice, water and a touch of salt. 90ml juice to 750ml water for the one I use. There used to be an FA document for referees on how to make your own with ratios for isotonic/hypotonic but can't find it now. This is a good article:
http://www.anitabean.co.uk/2014/07/really-need-sports-drink/

I do carry sachets of powdered drinks occasionally if I am on a long one and will be needing more than the 1 bottle drink and 1 bottle of water I carry normally. I use High 5 hydration tablets when the weather warms. No sign of sweeteners in there.

+1 on the torq and their gels are excellent too.

Torq are the only brand I would trust. Matt (the owner) lives locally and is involved with our club, we've talked about his products vs the competition and he takes pride in the quality of his products and the ingredients.

They aren't cheap, and he makes no apologies about that (KiwiMike might foam at the mouth if he compares the prices with stuff you can get in Tesco etc).  They also put money back into sport, sponsoring and supporting a significant number of athletes and events.

Just had a look at Torq and I've found your answer. No sweetners on the Torq energy ingredients list.

I have a rule that my meals are (almost always) made from real ingredients (avoid ready meals and other processed foods) but don't worry too much on the bike.

Just looked though and my SIS GO does contain some aspartame (and therefore phenylalanine). Perhaps better are CNP and ZipVit which use sucralose as a sweetner instead.

Seems like the main sports brands all tend to use some. The Viridian products are certainly natural, I haven't looked if the ratios and quantities of electrolytes are comparable though.

I've used this in my bottle for a while on long rides but most of the time just go for H2O:

http://www.viridian-nutrition.com/Shop/Sports-Electrolyte-Fix-Liquid-P69...

Just salt, chloride, potassium, and magnesium

Tastes better than coconut water and is cheaper

"I can't be bothered with mixing fruit juice and salt together."

Just pop some fruit juice or hi-juice squash in your bottle, skip the salt. Unless you're riding hard for several hours in the heat (not a problem in the UK just now) it won't make any difference. Putting electrolytes in sports drinks is about marketing, not science.

I have always used high5 zero electrolyte drink, not sure how this compares to what your currently using for sugar but worth looking at.

I always use Nuun electrolyte tablets. They taste good and seem to be about as "natural" as any off the shelf product. HTH