Batteries
Contents
Objectif
- obtenir des batteries au prix le plus bas possible, impliquant probablement un assemblage maison de cellules
- acquérir des connaissances dans le domaine des batteries, faire les choses selon les normes en vigueur, ne pas compromettre la sécurité
Applications
Batteries Lithium-ion
https://en.wikipedia.org/wiki/Comparison_of_battery_types
https://en.wikipedia.org/wiki/Lithium-ion_battery
Handheld electronics mostly use LIBs based on lithium cobalt oxide (LiCoO2), which offers high energy density, but presents safety risks, especially when damaged.
Lithium iron phosphate (LiFePO4), Lithium ion manganese oxide battery (LMnO or LMO) and lithium nickel manganese cobalt oxide (LiNiMnCoO2 or NMC) offer lower energy density, but longer lives and inherent safety. Such batteries are widely used for electric tools, medical equipment and other roles. NMC in particular is a leading contender for automotive applications.
Lithium nickel cobalt aluminum oxide (LiNiCoAlO2 or NCA) and lithium titanate (Li4Ti5O12 or LTO) are specialty designs aimed at particular niche roles.
The new lithium sulphur batteries promise the highest performance to weight ratio.
http://batteryuniversity.com/learn/article/types_of_lithium_ion
| caracteristics | LMnO / LMO | LiNiMnCoO2 / NMC | LiFePO4 |
|---|---|---|---|
| Voltages | 3.70V (3.80V) nominal; typical operating range 3.0–4.2V/cell | 3.60V, 3.70V nominal; typical operating range 3.0–4.2V/cell, or higher | 3.20, 3.30V nominal; typical operating range 2.5–3.65V/cell |
| Specific energy (capacity) | 100–150Wh/kg | 150–220Wh/kg | 90–120Wh/kg |
| Charge (C-rate) | 0.7–1C typical, 3C maximum, charges to 4.20V (most cells) | 0.7–1C, charges to 4.20V, some go to 4.30V; 3h charge typical. Charge current above 1C shortens battery life. | 1C typical, charges to 3.65V; 3h charge time typical |
| Discharge (C-rate) | 1C; 10C possible with some cells, 30C pulse (5s), 2.50V cut-off | 1C; 2C possible on some cells; 2.50V cut-off | 1C, 25C on some cells; 40A pulse (2s); 2.50V cut-off (lower that 2V causes damage) |
| Cycle life | 300–700 (related to depth of discharge, temperature) | 1000–2000 (related to depth of discharge, temperature) | 1000–2000 (related to depth of discharge, temperature) |
| Thermal runaway | 250°C typical. High charge promotes thermal runaway | 210°C typical. High charge promotes thermal runaway | 270°C Very safe battery even if fully charged |
| Applications | Power tools, medical devices, electric powertrains | E-bikes, medical devices, EVs, industrial | Portable and stationary needing high load currents and endurance |
| Comments | High power but less capacity; safer than Li-cobalt; commonly mixed with NMC to improve performance. | Provides high capacity and high power. Serves as Hybrid Cell. Favorite chemistry for many uses; market share is increasing. | Very flat voltage discharge curve but low capacity. One of safest Li-ions. Used for special markets. Elevated self-discharge. |
Formes
Li-ion cells (as distinct from entire batteries) are available in various shapes, which can generally be divided into four groups:
- Small cylindrical (solid body without terminals, such as those used in laptop batteries)
- Large cylindrical (solid body with large threaded terminals)
- Pouch (soft, flat body, such as those used in cell phones)
- Prismatic (semi-hard plastic case with large threaded terminals, such as vehicles' traction packs)
https://en.wikipedia.org/wiki/Lithium_polymer_battery
A lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated variously as LiPo, LIP, Li-poly and others), is a rechargeable battery of lithium-ion technology in a pouch format. Unlike cylindrical and prismatic cells, LiPos come in a soft package or pouch, which makes them lighter but also less rigid.
[...] "polymer" refers more to a "polymer casing" (that is, the soft, external container) rather than a "polymer electrolyte". While the design is usually flat, and lightweight, it is not truly a polymer cell, since the electrolyte is still in liquid form, although it may be "plasticized" or "gelled" through a polymer additive.
LiFePO4
http://batteryuniversity.com/learn/article/types_of_lithium_ion
high current rating and long cycle life, besides good thermal stability, enhanced safety and tolerance if abused.
Li-phosphate is more tolerant to full charge conditions and is less stressed than other lithium-ion systems if kept at high voltage for a prolonged time. As a trade-off, the lower voltage of 3.2V/cell reduces the specific energy to less than that of Li-manganese. With most batteries, cold temperature reduces performance and elevated storage temperature shortens the service life, and Li-phosphate is no exception. Li-phosphate has a higher self-discharge than other Li-ion batteries, which can cause balancing issues with aging.
Four cells in series produce 12.80V, a similar voltage to six 2V lead acid cells in series. Vehicles charge lead acid to 14.40V (2.40V/cell) and maintain a topping charge. With four Li-phosphate cells in series, each cell tops at 3.60V, which is the correct full-charge voltage. At this point, the charge should be disconnected but the topping charge continues while driving. Li-phosphate is tolerant to some overcharge; however, keeping the voltage at 14.40V for a prolonged time, as most vehicles do on a long drive, could stress Li-phosphate. Cold temperature operation starting could also be an issue with Li-phosphate as a starter battery.
Li-phosphate has excellent safety and long life span but moderate specific energy and elevated self-discharge.
LMnO / LMO
http://batteryuniversity.com/learn/article/types_of_lithium_ion
high thermal stability and enhanced safety, but the cycle and calendar life are limited.
Low internal cell resistance enables fast charging and high-current discharging. In an 18650 package, Li-manganese can be discharged at currents of 20–30A with moderate heat buildup. It is also possible to apply one-second load pulses of up to 50A. A continuous high load at this current would cause heat buildup and the cell temperature cannot exceed 80°C. Li-manganese is used for power tools, medical instruments, as well as hybrid and electric vehicles.
Design flexibility allows engineers to maximize the battery for either optimal longevity (life span), maximum load current (specific power) or high capacity (specific energy). For example, the long-life version in the 18650 cell has a moderate capacity of only 1,100mAh; the high-capacity version is 1,500mAh.
Most Li-manganese batteries blend with lithium nickel manganese cobalt oxide (NMC) to improve the specific energy and prolong the life span. This combination brings out the best in each system, and the LMO (NMC) is chosen for most electric vehicles, such as the Nissan Leaf, Chevy Volt and BMW i3. The LMO part of the battery, which can be about 30 percent, provides high current boost on acceleration; the NMC part gives the long driving range.
LiNiMnCoO2 / NMC
http://batteryuniversity.com/learn/article/types_of_lithium_ion
Similar to Li-manganese, these systems can be tailored to serve as Energy Cells or Power Cells. For example, NMC in an 18650 cell for moderate load condition has a capacity of about 2,800mAh and can deliver 4A to 5A; NMC in the same cell optimized for specific power has a capacity of only about 2,000mWh but delivers a continuous discharge current of 20A. A silicon-based anode will go to 4,000mAh and higher but at reduced loading capability and shorter cycle life. Silicon added to graphite has the drawback that the anode grows and shrinks with charge and discharge, making the cell mechanically unstable.
NMC is the battery of choice for power tools, e-bikes and other electric powertrains. The cathode combination is typically one-third nickel, one-third manganese and one-third cobalt, also known as 1-1-1. This offers a unique blend that also lowers the raw material cost due to reduced cobalt content. Another successful combination is NCM with 5 parts nickel, 3 parts cobalt and 2 parts manganese. Further combinations using various amounts of cathode materials are possible. New electrolytes and additives enable charging to 4.4V/cell and higher to boost capacity
NMC has good overall performance and excels on specific energy. This battery is the preferred candidate for the electric vehicle and has the lowest self-heating rate.
There is a move towards NMC-blended Li-ion as the system can be built economically and it achieves a good performance. The three active materials of nickel, manganese and cobalt can easily be blended to suit a wide range of applications for automotive and energy storage systems (EES) that need frequent cycling. The NMC family is growing in its diversity.
NCA
http://batteryuniversity.com/learn/article/types_of_lithium_ion
high specific energy, reasonably good specific power and a long life span. Less flattering are safety and cost
Li4Ti5O12 / LTO
http://batteryuniversity.com/learn/article/types_of_lithium_ion
Sulphure de lithium
http://batteryuniversity.com/learn/article/types_of_lithium_ion
Modèles de location
Puisque c'est un modèle commercial qui est pratiqué (en particulier s'agissant de certains véhicules électriques), il vaudrait la peine de le décrire/comprendre afin d'en tenir compte et de ne pas passer à côté de solutions économiquement intéressantes.
