Design of High Energy/High Power Lithium Polymer Electrolyte Batteries for Electronic Applications

摘要

Over the past two decades, a host of electronic devices have been developed to take advantage of dramatic advancements in battery technology. Increased energy density, improved display systems, reduced weight and smaller form factors have spurred the development of increasingly powerful electronic products. Lithium ion batteries represent a new class of commercially available lithium batteries with improved energy density (120 Wh/kg and 280 Wh/liter) and improved recharge cycle life (800 cycles). Another lithium ion technology now entering the final stages of commercialization uses a quasi solid-state polymer electrolyte as the ionic carrier. Polymer electrolytes offer thinner battery designs; cells can be stacked in series or parallel to form ultra thin battery packs with a variety of voltages and capacities; flexible configuration permitting them to conform to cavities with curved surfaces and lower costs. Despite these potential advantages, battery designers have failed to successfully manufacture batteries with consistent performance.rnThe Holy Grail for battery manufacturers is a system based on lithium metal as the anode and containing a wholly solid-state room temperature conducting polymer electrolyte. Such a system allows the use of very thin electrode/electrolyte structures and along with the use of less inactive components increases the overall energy density. In addition, this system would not suffer from the same charging and discharging problems as the present state-of-the-art lithium ion cells whereby overcharge results in solvent decomposition and gas evolutioa With this design, it is possible to achieve energy densities greater than 300 Wh/kg. Furthermore, cells can exhibit high power densities, fast-charge capabilities, and extremely low self-discharge and cycle life exceeding 1000 cycles. A totally solid-state design could be mass-produced more cost-effectively than lithium ion cells.