Lithium-ion battery or NiMH battery which is better? The difference between lithium-ion batteries and nickel-metal hydride batteries. Posted by benzoenergy.com
Nickel-metal hydride batteries and lithium-ion batteries are widely used in the market. They are non-polluting and environmentally friendly batteries and are important areas for new energy development. So which is better, Ni-MH battery or Li-ion battery?
The difference between lithium-ion batteries and nickel-metal hydride batteries
Structurally,
the positive electrode of the nickel-hydrogen battery is Ni(OH), the
negative electrode is metal hydride, and the electrolyte is 6mol/L
potassium hydroxide solution. The lithium ion battery
is a negative electrode by inserting lithium ions into petroleum coke
and graphite. The positive electrode material is usually LixCoO2,
LixNiO2 or LixMnO4. The electrolyte composition is relatively complex,
and LiPF6 + diethylene carbonate + dimethyl carbonate is mixed in
proportion.
Due to its mature technology and good safety, nickel-metal hydride batteries
are an important choice for hybrid electric vehicle (HEV) batteries,
but it is difficult to meet the demand for higher electrification;
nickel-metal hydride lithium batteries currently dominate the existing
hybrid vehicles. The energy of the battery is only 1-2kWh, and it cannot
be driven by pure electric power or with a battery life of less than
3km.
In the longer term,
NiMH cannot be applied to PHEVs and EVs. Mainly because the specific
energy and energy density of nickel-hydrogen cannot meet the
requirements of PHEV and EV; the raw material Ni(OH) is expensive, and
the cost of manufacturing high-energy batteries will be higher; the
development of nickel-hydrogen battery technology is basically mature,
and battery performance is improved. And the room for cost reduction is
very limited.
Nickel-metal
hydride batteries and nickel-cadmium batteries have the same memory
effect, but they are much smaller than nickel-cadmium batteries. So
there is no need to perform a discharge operation every time it is
charged (because improper operation will damage the battery), it only
needs to be fully charged and discharged once every three months to
alleviate the memory effect.
Nickel-metal
hydride batteries are 25-35% (months), and lithium-ion batteries are
2-5% (months). Nickel-metal hydride batteries have a high self-discharge
rate, while lithium-ion batteries have a very low discharge rate.
At
present, the capacity of general nickel-hydrogen battery can reach
2900mAh (mah-hour, which is commonly called mAh in mainland my country
as r milliamp-hour). device), and lithium-ion batteries have a chance of
burning or exploding if they are not in use. Relatively speaking,
nickel-metal hydride batteries are the safest batteries.
The
voltage of nickel-hydrogen battery is 1.2V, and the voltage of
lithium-ion battery is 3.7V. The lithium-ion battery has better
discharge and discharge performance.
Nickel-metal
hydride batteries have low environmental pollution, mainly some acid
and alkali waste gas, and the most harmful one is HCI. There should be
no problem if environmental protection measures are in place.
Comparing lithium-ion batteries with nickel-metal hydride batteries, the advantages are mainly reflected in:
1.
High specific energy and energy density, about twice that of
nickel-metal hydride batteries, which can greatly improve the battery
life of electric vehicles. Higher power, small self-discharge, and no
memory effect can improve the convenience of electric vehicles. ;
2. Low cost of raw materials;
3. There is a lot of room for technological improvement and a lot of room for cost reduction.
4.
Volume: Rechargeable lithium-ion batteries are widely used in many new
mobile devices because they have the advantages of small size
(relatively), light weight, low self-discharge rate and no memory effect
compared with ordinary nickel-cadmium/nickel-metal hydride batteries. .
The batteries of mobile phones, notebook computers, PDAs and other
mobile devices we usually use have been gradually replaced by
lithium-ion batteries.
The
memory effect of NiMH batteries is not very obvious, a little bit. When
it is urgent to use, it is not necessary to discharge the light and
then recharge it. It is best to discharge the light and then fill it in
normal use.
5.
Power: Lithium-ion battery has large energy and small battery; the
voltage of a single lithium-ion battery is 3 times that of
nickel-hydrogen battery; there is no memory effect, and it can be
charged at any time. But it can't be charged at a time, so too many
times of charging and discharging will affect the life of the battery.
Lithium-ion batteries are not suitable for long-term storage, as they
will permanently lose part of their capacity over time. It is best to
store it in the freezer of the refrigerator after charging 40%.
6.
Charging method: The charging requirements of lithium-ion batteries are
different from those of nickel-cadmium/nickel-metal hydride batteries.
The single-unit voltage of rechargeable lithium-ion batteries is 3.6V
(some battery blocks may be called as lithium-ion batteries).
Lithium-ion batteries are generally charged by the voltage-limiting and
current-limiting method. If a friend wants to charge the lithium-ion
battery independently, it should be noted that its charging method is
different from the constant current charging method used by
nickel-cadmium/nickel-hydrogen batteries and cannot be used. Charger for
ordinary NiCd/NiMH batteries.
Although
nickel-metal hydride batteries and lithium-ion batteries are different,
they are all energy batteries in the new era, and they have played an
irreplaceable role in the progress of human life! Objective evaluation,
when the weight becomes a key factor affecting the performance of the
product and the battery can be maintained in time, the use of
lithium-ion batteries is a matter of course, and when high power, good
safety, high reliability and economical practicability are required ,
NiMH batteries will be more advantageous.
BENZO Energy Technology Co.,Ltd
UFine Technology Co., Ltd
Site: www.bz-battery.com / www.benzoenergy.com
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