Regardless of battery chemistry—alkaline,nickel cadmium (NiCd),or nickel metal hydride (ni-mh battery)—in single-cell applications the battery voltage can be drained as low as 0.8 V-0.9 V when the battery is finally empty.Ideally,the dc/dc boost converter start-up/operating voltage range should be specified down to this voltage range.This is true of Texas Instruments’ TPS6101x family of devices;the start-up voltage is specified as 0.9 V to alleviate potential issues regarding start-up in such a low-voltage condition.After the device is started,it can be operated down to 0.8 V.
Scientists at the U.S.Army Research Laboratory have made a breakthrough in battery energy density that could lighten the load of soldiers in the field and eventually lead to better batteries in our electronics.The scientists discovered that by adding a new substance to a single cell battery they could boost the energy density from four volts to five,a 30 percent increase.”There has never been a battery,a single cell,that operated at five volts,” Cynthia Lundgren,electrochemical branch chief at the laboratory explained. “Through our understanding of that interface,we were able to design an additive that you add into the electrolyte that is somewhat of a sacrificial agent.It preferentially reacts with the electrode and forms a stable interface.Now the battery is able to operate at five volts.”
The Army has patented the technology and informed the battery industry of the breakthrough,which means it could make its way into our gadgets soon.The Army hopes to use this discovery to create lighter batteries with higher densities for soldiers to carry,making more room in their battery packs for water or other essentials.Ultimately though the lab wants to focus on designing power systems that run on renewable energy or readily available sources like water.One idea is to create small fuel cells that run on hydrogen that has been split from water.
Texas Instruments’ TPS61070/1 devices have a typical start-up voltage specified as 1.1 V (with a worst case start-up voltage of 1.2 V).However,once started,these devices can operate at < 0.9 V.The typical specified battery voltage in data specifications for NiMH batteries is 1.2 V.The typical discharge curve of both nickel and alkaline batteries is a non-linear curve from 1.5 V down to 0.9 V (with some battery capacity remaining when the battery voltage is below 1.2 V).These battery voltage specifications,and the start-up specifications of the TPS61070/1,generated some questions as to whether it is suitable for single-cell battery applications.In both cases,device start-up and battery energy utilization,the TPS61070 works well in single-cell applications.
Army researcher Arthur Cresce,who helped design the substance two years ago said,”This is what you would call a quantum leap.We’ve gone from circling around a certain type of four volt energy for quite a while.All of a sudden a whole new class of batteries and battery voltages are open to us.The door is open that was closed before.”For both soldiers and civilians,better batteries open up greater possibilities for using renewable energy to fuel our gadgets and other electronics. Greater density and better materials mean better storage for things like solar or wind power that can be inconsistent sources of energy,but the best and cleanest options.