Battery tech refers to which battery chemistry a specific EV model is using, including what cells (if the information is publicly available), and the platform voltage. The higher the voltage of the platform's electrical system, the faster it's possible to make DC charging, provided compatible charging infrastructure, of course.
The most common EV battery types are Li-Ion and Li-Polymer, because of their high energy density compared to their weight. Since the late 1990s, advances in lithium-ion battery technology have been driven by demands from portable electronics, laptop computers, mobile phones, and power tools. The BEV and HEV marketplace has reaped the benefits of these advances both in performance and energy density. Unlike earlier battery chemistries, notably nickel-cadmium, lithium-ion batteries can be discharged and recharged daily and at any state of charge.
However, new data has shown that exposure to heat and the use of fast charging promote the degradation of Li-ion batteries more than age and actual use, and that the average electric vehicle battery will retain 90% of its initial capacity after 6 years and 6 months of service. Active cooling systems are very important to deter degradation - a battery system without an active cooling system may degrade twice as fast as one that does.
Recent EVs are using new variations on lithium-ion chemistry that sacrifice specific energy and specific power to provide fire resistance, environmental friendliness, rapid charging (as quickly as a few minutes), and longer lifespans. These variants (phosphates, titanates, spinels, etc.) have been shown to have a much longer lifetime, with A123 types using lithium iron phosphate lasting at least more than 10 years and more than 7000 charge/discharge cycles, and lithium-manganese spinel batteries expected to last up to 40 years.