Ni-MH battery is a kind of battery with good performance. Ni-MH batteries are divided into high-voltage nickel-hydrogen batteries and low-voltage nickel-hydrogen batteries. The positive electrode active material of nickel-hydrogen battery is Ni(OH)2 (called NiO electrode), the negative electrode active material is metal hydride, also called hydrogen storage alloy (electrode is called hydrogen storage electrode), and the electrolyte is 6mol/L potassium hydroxide solution. As an important direction of hydrogen energy application, nickel-metal hydride batteries are getting more and more attention.
Structure and principle
Ni-MH battery is a kind of battery with good performance. Ni-MH batteries are divided into high-voltage nickel-hydrogen batteries and low-voltage nickel-hydrogen batteries. The positive electrode active material of nickel-hydrogen battery is Ni(OH )2 (called NiO electrode), the negative electrode active material is metal hydride, also called hydrogen storage alloy (electrode is called hydrogen storage electrode), and the electrolyte is 6mol/L potassium hydroxide solution. As an important direction of hydrogen energy application , nickel-metal hydride batteries are getting more and more attention.
What is the essential difference between lithium batteries and nickel-metal hydride batteries? Lithium batteries are more suitable for use in mobile phones, but if we use digital cameras, the amount of current that needs to be continuously generated at that moment needs to be very large and consumes electricity. The volume is also much larger than that of mobile phones, so we use Ni-MH batteries a little better. Next, let's continue to take a look.
lithium battery
Advantages and disadvantages of lithium batteries
Advantages: no memory effect, lighter total weight.
Disadvantages: The cost is relatively high, the working current is small, and it cannot be overcharged (compared with NiMH).
Lithium batteries have primary lithium batteries (non-rechargeable) and secondary lithium batteries (rechargeable), and secondary lithium batteries are divided into Li-ion lithium-ion batteries and Li-Polymer lithium polymer batteries.
Generally, digital cameras use secondary lithium batteries (rechargeable). Compared with nickel-hydrogen batteries, the total weight is relatively light, and the volume-to-power density ratio is higher than 48%. Because of this, the production and sales of lithium-ion secondary batteries are gradually surpassing nickel-hydrogen batteries. This kind of battery itself has small discharge and no memory effect, and the number of charge and discharge can reach more than 600 times. Especially the Li-Polymer battery developed in recent years. In addition to its smaller size, it is not affected by the battery under normal conditions. The cylindrical or square appearance is limited, and the total weight is also lighter.
Lithium batteries are not resistant to overcharging, and there is a danger of explosion if they are used carelessly. Therefore, a built-in control IC is required to avoid overcharging, but the cost is relatively high. Since the specifications of lithium batteries are not uniform, there will be cases where the batteries cannot be purchased after the production is discontinued. However, many improvements have been made.
Advantages and disadvantages of nickel-metal hydride batteries
Advantages: low price, strong versatility, large working current, stable environmental protection.
Disadvantages: The total weight is large, and the battery life is short.
The design of nickel-metal hydride batteries originated from nickel-cadmium batteries, but great progress has been made in improving the memory effect of nickel-cadmium batteries. The main change is the replacement of the cadmium used in the negative electrode with a hydrogen storage alloy, so the nickel-hydrogen battery can be said to be a typical representative of material innovation. The pollution caused by nickel-metal hydride batteries is much smaller than that of nickel-cadmium batteries containing cadmium. Therefore, nickel-cadmium batteries have been gradually replaced by nickel-metal hydride batteries.
Except for a few lithium batteries that can be used once (NIKONEN-EL1 and 2CR5), most of the lithium batteries do not have a battery alternative. This is very troublesome for long-term overseas trips or large numbers of users. Ni-MH batteries have no such problem. In digital cameras that use nickel-metal hydride batteries, alkaline batteries can usually be used instead.
In recent years, more and more digital cameras are using Ni-MH batteries. Battery manufacturers are also optimistic about this market. They have released high-capacity Ni-MH rechargeable batteries, which has promoted the rapid development of Ni-MH battery technology, and the capacity has become larger and longer. Comparing with lithium batteries, even the charger has become more sophisticated, and the charging time has been drastically shortened.
The difference between Ni-MH battery and lithium battery
1. High power density: The capacity of nickel-hydrogen battery is close to that of nickel-cadmium battery and lithium-ion battery, which can determine the characteristics of the coordinated enterprise product of nickel-hydrogen battery. It is necessary to pay attention to the certain difference in power density, which is exactly the same. The energy that can be stored in any capacity, the lithium-ion battery is three times that of the nickel-hydrogen battery.
2. Self-discharge rate: The self-discharge rate usually refers to the amount of power that the battery will lose by itself when the battery is not in the strong state. The self-discharge rate of nickel-hydrogen battery and lithium-ion battery is not very large, but the self-discharge rate of nickel-hydrogen battery exists for a long time. If the self-discharge rate is too large, the battery usage period will be greatly shortened, and the service life will end earlier. This caused the low self-discharge rate Ni-MH battery to be an advantage of Ni-MH battery promotion in the past ten years ago, and the self-discharge rate of Li-ion battery can be ignored, which is also the raw material used between each other. Causes green ecological differences in chemical properties.
3. In use: Under normal circumstances, the lithium battery can be charged, used, and stopped at any time. Cycle life refers to the number of full charge and full discharge, and partial charge and discharge can be understood as a fraction of the life. The key to using the battery: the battery is fully charged, it can be charged for 20 minutes to half an hour to reach saturation, but it must be avoided to charge for a long time after being fully charged. Continuing to charge for a long time after full charge will cause side effects. As a result, the capacity will decrease and the internal resistance will increase. The capacity will be greatly shortened, and the device will shut down as soon as a call is made. It is best to use PPC and other machines with power chips until they are discharged. The main reason is to consider the issue of power display and measurement.
Which is better, nickel-metal hydride battery or lithium battery?
Ni-MH batteries and lithium batteries are better. In fact, it's really hard to say. It mainly depends on what products you use. For example, if you choose to use on mobile phones, tablets, and electric bicycles, I recommend using lithium batteries. , Fully consider the long cycle life, but on the digital SLR camera, fully consider that the digital SLR camera has a very large demand for current, and the power consumption is also larger than that of the mobile phone. In terms of large working current output, Ni-MH The battery is slightly higher.
In recent years, more and more digital cameras are using Ni-MH batteries. Battery manufacturers are also optimistic about this market. They are racing to promote high-capacity Ni-MH rechargeable batteries, which has promoted the rapid development of the technological level of Ni-MH batteries and their capacity is increasing. The use time is comparable to that of the lithium battery, and even the charger has become more and more sophisticated. The charging time has been greatly reduced after the fast charging and flash charging function.
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