Nanoarchitectures for lithium-ion batteries

Nanoarchitectures for lithium-ion batteries are attempts to employ nanotechnology to improve the design of lithium-ion batteries. Research in lithium-ion batteries focuses on improving energy density, power density, safety, durability and cost. Nanoarchitectures for lithium-ion batteries are attempts to employ nanotechnology to improve the design of lithium-ion batteries. Research in lithium-ion batteries focuses on improving energy density, power density, safety, durability and cost. Increased energy density requires inserting/extracting more ions from the electrodes. Electrode capacities are compared through three different measures: capacity per unit of mass (known as 'specific energy' or 'gravimetric capacity'), capacity per unit volume ('volumetric capacity'), and area-normalized specific capacity ('areal capacity'). Separate efforts focus on improving power density (rate of charge/discharge). Power density is based upon mass and charge transport, electronic and ionic conductivity, and electron-transfer kinetics; easy transport through shorter distance and greater surface area improve the rates. Carbon anodes are traditionally used because of lithium's ability to intercalate without unacceptable volumetric expansion. The latter damages the battery and reduces the amount of lithium available for charging. Reduced intercalation limits capacity. Carbon based anodes have a gravimetric capacity of 372 mAh/g for LiC6. The specific capacity of silicon is approximately ten times greater than carbon. The atomic radius of Si is 1.46 angstroms, while the atomic radius of Li is 2.05 angstroms. The formation of Li3.75Si causes significant volumetric expansion, progressively destroying the anode. Reducing the anode architecture to the nanoscale offers advantages, including improved cycle life and reduced crack propagation and failure. Nanoscale particles are below the critical flaw size within a conductive binder film. Reducing transport lengths(the distance between the anode and cathode) reduces ohmic losses (resistance). Nanostructuring increases the surface area to volume ratio, which improves both energy and power density due to an increase in the electrochemically active area and a reduction in transport lengths. However, the increase also increases side reactions between the electrode and the electrolyte, causing higher self-discharge, reduced charge/discharge cycles and lower calendar life. Some recent work focused on developing materials that are electrochemically active within the range where electrolyte decomposition or electrolyte/electrode reactions do not occur. A research concept has been proposed, in which the major parts of lithium-ion batteries, that is, anode, electrolyte and cathode are combined in one functional molecule. A layer of such functional molecules aligned by the use of Langmuir-Blodgett method than placed in between two current collectors. The feasibility is not confirmed yet. A significant majority of battery designs are two–dimensional and rely on layered construction. Recent research has taken the electrodes into three-dimensions. This allows for significant improvements in battery capacity; a significant increase in areal capacity occurs between a 2d thick film electrode and a 3d array electrode.