Powergenix 1.6-Volt Nickel-Zinc AA Rechargeable

Finally, a rechargeable battery that delivers as much juice as disposables. PowerGenix took high-power-producing nickel-zinc chemistry, typically too short-lived to be useful, and increased its life span 10-fold by using a water-based electrolyte that doesn’t dissolve the vulnerable zinc. Now it lasts up to 1,000 charges, as long as any other rechargeable, while putting out 1.6 volts, beating current 1.2-volt rechargeables and matching the 1.5-volt throwaway alkalines that most gadgets are designed for.
$15/four-pack; powergenix.com