22 Years' Battery Customization
Aug 03, 2023 Pageview：305
Definition of High Voltage Lithium Polymer Battery
LiPo (Lithium-ion Polymer) battery cells having normal voltages can be charged fully at 4.2V. On the other hand, high cut-off charging voltage of LiHv (lithium high-voltage polymer) cells is allowed at 4.45V, 4.4V or 4.35V.
About LiHv battery
It is considered to be another Lithium-ion Polymer battery type. Here ‘Hv’ is in short for ‘high voltage’. Unlike traditional LiPo batteries, it is highly energy intensive. It can charge at 4.35v or even higher per cell. Regular LiHv battery peak cell voltage is around 4.2v while nominal voltage is around 3.65-3.7V.
Characteristics of High Voltage Lithium Polymer Battery
Lipo battery is applied to different types of equipment. It includes cameras, mobile phones, cordless telephone, laptops, cameras, electronic toys, remote control, various electronic devices, etc. Its different characteristics are:
High voltage. 3.6v single cell voltage is equivalent to 3 Ni-MH battery or nickel-cadmium battery placed in series.
Higher volume-energy rate and weight-energy rate.
No memory effect. This battery lack memory effect like Lithium-Cadmium battery. Hence, no discharge is noticed before charging.
Keep for long due to low self-discharging rate, undoubtedly a major advantage.
Charges quickly. The charging prioress requires only 0.5-1 time of current thereby reducing charging time to 1-2 hours.
Long lifespan. Cycle times during in case of working conditions of charging/discharging are over 500.
World’s most advanced and sophisticated ‘green’ battery. It is environment-friendly and lacks heavy metal element such as mercury, lead or cadmium.
Used in parallel.
High cost. Lipo battery is found to be more expensive when compared to other batteries.
Internal Structure
Often Lipo battery is divided into rectangular and cylinder shapes. It has spiral internal structure that places highly permeable and precise polyethylene films as partition in-between anode and cathode. Anode comprises of Li-ion collector created in Lithium while current collector and CoO2 is created in aluminum film. Li-ion collector in cathode is of carbon sheet materials while current collector is created in bronze film. Organic electrolyte solution is filled in the battery. Apart from this, there is designed PTC and safety valve to safeguard battery in short out or abnormality. Single cell voltage is 3.6v something not infinite capacity. Hence, placing single li battery in parallel or series is common to meet growing demands.
Charging Tips of High Voltage Lithium Polymer Battery
Lithium-ion batteries of industrial grade power your portable device or remote. Such batteries offer high energy density and ruggedized design for longevity. It can also withstand extreme temperatures. Longevity is related directly to how battery is charged/discharged, operating temperatures
Tips to Follow
Respect CCCV charging process on floating mode. Lithium-ion battery charging is a tough process. Selected charger will have key role since the established parameters will impact battery lifetime. Do not use charger that is meant to charge other devices. Avoid plugging it on power supply to avoid safety issues. Lithium-ion battery can be charged properly following two steps. CC (Constant Current) followed by CV (Constant Voltage). CC charge is applied to ensure voltage is brought up to voltage end-of-charge level. Target voltage can also be reduced to preserve electrode. On reaching desired voltage, CV charging starts while current reduces. Charge is completed as current is extremely low. Current needs to be removed. Battery capacity is based directly on voltage end-of-charge. Hence, battery capacity is reduced by reducing voltage. Right trade-off is desired between required autonomy, battery longevity and minimum voltage to ensure optimum device efficiency. However, floating mode is not suggested since it can damage battery in the long-run.
Understand battery language: Two electrodes are used in Lithium-ion batteries, namely positive and negative. On discharging or charging the battery, electrons go outside battery via electrical current while ions flow between electrodes. As battery releases current, electrons tend to move outside it between anode and cathode. Reverse current can be applied that enables auto-recharging of the battery. In such a case, electrons go back to anode while lithium ions re-intercalate in cathode, thereby restoring battery capacity. Charging/discharging process can be referred to as cycle. Number of cycles batteries can perform will depend on manufacturing process, actual usage and chemical components.
Lowering charging C rate: Lithium ions at low-charging speeds (which are C/5, C/2 or less) can intercalate smoothly in graphite sheets, but without damaging electrodes. With increase in charge rate, intercalation gets harder. Too strong rate will mean lithium ions not having time to penetrate properly the electrode. It will only deposit on the surface thus causing premature aging. 4C or 10C fast charging rates are possible. Right trade-off is desired between essential speed, charging time and battery age. For electrodes, C/50 charging rate can be a good choice. However, not every application will be able to afford charging time of over 50 hours. 30 minutes (2C) charging time is possible. However, it accelerates battery age. Hence, charge rate should be limited to C or less MP range.
Design BMS carefully: Irrespective of the application to be used, Li-ion cells are to be related to electronics. Key electronic component can be termed as BMS (Battery Management System). Mandatory safety feature might interrupt charge/discharge. The objective is to safeguard battery against undervoltage or overvoltage. BMS checks temperature while battery is disconnected to prevent overheating. BMS incorporates electronics by optimizing homogenous charge between the cells within the battery pack. It is referred to as balancing. With BMS not having balancing feature, most aged cells in the pack is likely to age faster. Moreover, good balancing system can enhance battery’s lifespan.
Controlling charging temperature: Li-ion batteries mostly use graphic material within the electrode. Graphite sheet exfoliation is provoked by increasing charging temperature. However, it hastens battery’ permanent loss capacity. High charging rate aggravates the phenomenon. Charging current enhances temperature thereby resulting in hastening of exfoliation phenomenon. High temperature along with high voltage level results in gas generation from electrochemistry within the cell. It only accelerates chemistry ageing. High temperatures may generate cell swelling based on cell construction, thus causing safety hazards.
Therefore, following the above tips can help optimize industrial-grade lithium-ion battery lifespan.
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