The following improvement to the lithium air battery is being researched . These have always had the potential to have far greater energy density than conventional lithium ion batteries but they had technical problems . This innovation appears to have solved many of the technical problems with an energy density close to that of gasoline .
Published online in Nature Chemistry June 10 , 2012
Here is a brief excerpt of the article :
An improved high-performance lithium–air battery
Hun-Gi Jung1,3, Jusef Hassoun2, Jin-Bum Park1, Yang-Kook Sun1,3* and Bruno Scrosati1,2*
Although dominating the consumer electronics markets as the power source of choice for popular portable devices, the common lithium battery is not yet suited for use in sustainable electried road transport. The development of advanced, higher-energy lithium batteries is essential in the rapid establishment of the electric car market. Owing to its exceptionally high energy potentiality, the lithium–air battery is a very appealing candidate for fullling this role. However, the performance of such batteries has been limited to only a few charge–discharge cycles with low rate capability. Here, by choosing a suitable stable electrolyte and appropriate cell design, we demonstrate a lithium–air battery capable of operating over many cycles with capacity and rate values as high as 5,000 mAh g carbon 2 1 and 3 A gcarbon 2 1 , respectively. For this battery we estimate an energy density value that is much higher than those offered by the currently available lithium- ion battery technology.
The lithium–air battery has, in principle, a very high energy density, often reported as approaching that of gasoline1,2, and it is this exceptional energy potentiality that has triggered worldwide interest in this super energy storage system. However, despite extensive research efforts devoted to its practical implemen- tation, several issues regarding both the electrodes and electrolytes have so far limited the performance of the lithium–air battery to just a few charge–discharge cycles and a low rate capability3.
In its most common conguration, the lithium–air battery com- prises a lithium-metal anode, a lithium conducting organic electro- lyte and a carbon-supported (with or without catalyst) air electrode4. The oxygen reduction process leads to the formation of lithium per- oxide (Li2O2) via a sequence of intermediate steps that also includes the formation of an oxygen radical anion O2 †2 (refs 5,6), a highly reactive base that readily decomposes most electrolytes, including the organic carbonate solutions commonly used in lithium-ion bat- teries. Indeed, attempts to operate lithium–air batteries based on these electrolytes failed after few cycles as the overall process becomes dominated by electrolyte decomposition3,7. Accordingly, the choice of a stable electrolyte is one of the challenges in lithium–air research and development.
Possible examples of such an electrolyte are di-methoxy ethane (DME)-based8 and ionic liquid-based9 solutions; however, their use may be limited by overpressure (in the DME case) or by cost (in the ionic liquid case). Polymer electrolytes such as those based on the combination of poly(ethylene oxide) (PEO) and a lithium salt (for example, lithium triate, LiCF3SO3) have also been con- sidered as suitable lithium–air battery media5,10. In these cases, the limitation arises from the thermal dependence of the ionic con- ductivity, which reaches acceptable values only at temperatures above 70 8C (ref. 10). Promising alternatives are end-capped glymes11 such as tetra(ethylene) glycol dimethyl ether, which, due to their high solvating power and low sensitivity to the oxygen reduction products, are indeed expected to be stable and efcient electrolyte media. We assume that this stability is associated with the chemical inertia of the ether groups, which is much higher than that of the carboxyl groups of conventional organic carbonate solutions. In fact, we demonstrate in this work that a lithium–air battery with an optimized glyme-based electrolyte may operate effectively for many cycles at high current rates without any decay in capacity. To our knowledge, this is the rst time that a lithium–air battery with this level of performance has been described.
Results and discussion
The oxygen electrode in glycol electrolyte lithium–air cells. The oxygen electrochemical process in lithium cells with a tetra(ethylene) glycol dimethyl ether–lithium triate (TEGDME– LiCF3SO3) electrolyte was analysed using potentiodynamic cycling with galvanostatic acceleration (PCGA). PCGA provides quasi- thermodynamic information about a given electrochemical process, much like the similar potentiostatic intermittent titration technique (PITT)12,13. The PCGA test is generally performed by applying a potential step to an electrochemical cell near to the initial equilibrium value, and monitoring the resulting current for a time sufcient for a new equilibrium potential to be reached. A series of potential steps with small difference in value are then applied sequentially to the cell and the corresponding chronopamperometric response is recorded. Integration of the latter gives the charge increment, dQ. On completing the experiment , a set of 'incremental capacity' values dQ can be plotted versus step potential V.
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