Amazon is readying a higher-end Kindle e-reader that features a rechargeable protective case to extend battery life. According to an individual familiar with the new device, the removable case will allow for a thinner Kindle. The company is also said to be developing a case that charges Kindle’s battery using solar power, although it will not be ready for immediate availability. “The new Kindle and case are code-named ‘Whiskey’ and ‘Soda,’ respectively, and the solar-powered case is known internally as ‘Sunkiss’ among engineers at Lab126,” reports The Wall Street Journal. Amazon chief exec Jeff Bezos tweeted Monday that an “all-new, top of the line Kindle” is nearly ready, and details will be offered next week.