First, in terms of battery prices, lithium batteries are more expensive than lead-acid batteries.
For example, a set of lead-acid batteries on the market now costs between four and five hundred yuan, while lithium batteries of the same energy generally cost more than a thousand yuan. a lithium iron phosphate battery is even more expensive. Therefore, in terms of price, lithium batteries generally cost twice or more than lead-acid batteries.
Second, in terms of battery capacity, lithium batteries of the same size have more capacity.
Because the average voltage of lithium batteries is higher than that of lead-acid batteries, that is, the energy density is high, so for batteries of the same volume , lithium batteries have greater capacity.
Regarding the same lithium battery, the capacitytee of ternary lithium battery is higher than that of lithium iron phosphate battery, and the capacity of lithium iron phosphate battery is higher than that of lithium manganate battery.
Third, in terms of battery weight, lithium batteries of the same volume are lighter than lead-acid batteries.
This means that the energy density of lithium batteries is greater. For example, the energy of one kilogram of lithium batteries is equivalent to the energy of three to five kilograms of lead-acid batteries. therefore the same energy. Then, lead-acid batteries are heavier.
So if we want to be more convenient and lighter to twist, we can choose lithium batteries.
Fourth, in terms of battery safety, lead-acid batteries are safer.
The main component of lead-acid batteries is water, there is no organic electrolytenic and explosions or fires are rare.
However, lithium batteries have a certain sealed space and contain organic materials if used improperly, explosions and fires may occur.
Fifth, in terms of battery life, lithium batteries are about three times longer than lead-acid batteries.
The standard for this judgment is that for the same quality, the number of cycles of lithium batteries is about 1,000 times, and that of lead acid batteries is about 300 times. times. if you use lead acid battery, you need to recharge it after 300 times charging, the battery will basically enter the aging stage, so the lifespan of lithium batteries will be longer.
Lithium battery electrolyte is an important component of the battery and has a great impact on battery performance.
In thetraditional batteries, the electrolytic system uses water as a solvent.
However, since the theoretical voltage for water decomposition is only 1.23 V, even taking into account the overpotential of hydrogen or oxygen, the maximum voltage of the battery with an electrolytic system using water as a solvent is only about 2 V (like a lead acid battery).
The voltage of lithium batteries reaches 3-4V. The traditional aqueous solution system is obviously no longer suitable for the needs of batteries, and a non-aqueous electrolyte system must be used as the electrolyte of lithium-ion batteries.
Lithium battery electrolytes mainly use organic solvents and electrolytes that can withstand high voltages without decomposing.
The electrolyte used in lithium-ion batteries is a lithium salt electrolyte dissolved in an organic solvent. of ionic conductors.
Generally, as an organic electrolyte for practical lithium-ion batteries, it should have the following properties: (1) High ionic conductivity, which should generally reach 10-3——2*10- 3S/cm;
The migration number of lithium ions should be close to 1;
(2) The potential range of electrochemical stability is wide;
There should be an electrochemical stability window of 0-5V;
(3) Good thermal stability, wide operating temperature range;
(4) Stable chemical properties , no chemical reaction with current collectors and non-toxic substances present in the battery;
(5) Safe and low toxic, preferably biodegradable.
Suitable solvents should have a high dielectric constant and low viscosity. Commonly used solvents include alkyl carbonates such as PC and EC, which are highly polar and have a dielectric constanthigh tric, but have high viscosity and intermolecular forces. , lithium ions move slowly there.
Linear esters such as DMC (dimethyl carbonate) and DEC (diethyl carbonate) have a low viscosity but also a low dielectric constant. Therefore, in order to achieve high ionic conductivity, for liquid solutions, mixed solvents such as PC+. DEC and EC+DMC are generally used.
These organic solvents have some odor, but generally speaking, they can meet EU RoHS and REACH requirements. These are very toxic and environmentally friendly materials.
The currently developed inorganic anion conductive salts mainly include three categories: LiBF4, LiPF6 and LiAsF6. Their conductivity, thermal stability and oxidation resistance are in the following order: Conductivity: LiAsF6≥LiPF6>LiClO4>LiBF4 Thermal stability. :LiAsF6>LiBF4>LiPF6 Oxidation resistance: LiAsF6≥LiPF6≥LiBF4>LiClO4 LiAsF6 has very high conductivity, stability and battery charge and discharge rate, but arsenic toxicity limits its application.
Currently, the most commonly used is LiPF6.
All materials of currently commonly used lithium batteries, including electrolytes, comply with EU RoHS and REACH requirements and are environmentally friendly energy storage products.