I wouldn't, and don't, worry about it. Speaking as a EE, but not involved with lithium ion batteries in my career, it doesn't look to me like the battery tech is improving much at all. Maybe you get a couple of percent better capacity next year, but it's certainly not like "Moore's Law" from the old days in computer performance, doubling every couple of years (although we hit Moore's law's limits in computers about a decade ago).