How Are They Packing All That Energy In Such A Small Space?
Battery manufacturers are packing more active material into a cell making the electrodes and separator thinner. This enables a doubling of energy density since lithium-ion was introduced in 1991. Meaning, this provides our devices with more power and battery life.
What Effects Does This Have On The Battery?
The short answer is safety concern. There are two leading causes in the short circuiting of lithium-ion batteries. Overheating and penetration. There have been many reports in regards to the effect of heat and penetration of the lithium-ion battery. When lithium-ion batteries are over heated the cells short circuit causing the safety separators to shrink, meld, crack and split which leads to thermal runaway. Thermal runaway is defined as a situation where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result. Another contributing factor could be aging, rough handling, and excessive vibration.
When the lithium-ion battery is penetrated the cell theoretically become a ticking bomb. The result is not always instantaneous. Once the heat release starts, the thermal runaway is VERY fast and temperatures can reach as high as 900 ̊C.
Is There Hope?
Lithium-ion batteries are nearing their energy density limit and battery manufacturers are forced to look at improving manufacturing methods and increasing safety. Most safety separators are 25microns in thickness but some of the separators go down to 20 microns, 16 microns and now even to 12 microns without significantly compromising the properties of the cell. Ultrathin separators raise safety concerns and on rare occasions microscopic metal particles may come into contact with other parts of the battery cell, leading to an electrical short circuit within the cell.
Considering the number of lithium-ion batteries used on the market, this energy storage system has caused little harm in terms of damage and personal injury. However, in spite of the good record, its safety is a hot topic that gets high media attention, even on a minor mishap. Cell manufacturers have been cautioned and are not only trying to pack more energy into the cell but will attempt to make it more bulletproof.