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Which is negative positive on battery?

Batteries are a crucial component of many devices we use every day, from phones and laptops to cars and power tools. While battery technology has improved over the years, all batteries still have positives and negatives associated with their use. In this article, we will look at the different types of batteries, weigh the pros and cons of each, and determine which ones are best and worst for the environment.

How Batteries Work

First, let’s review the basics of how batteries work. A battery contains one or more cells that each have three main components: a positive electrode, a negative electrode, and an electrolyte solution. The positive and negative electrodes are typically made of different materials that create a voltage difference when electrons flow between them through the electrolyte. This flow of electrons from one electrode to the other is what provides power.

During discharge when a device is powered on, the battery’s negative electrode undergoes an oxidation reaction, which releases electrons. These electrons travel through the external circuit to the positive electrode, where they cause the positive electrode material to undergo a reduction reaction. The electrolyte allows ions to flow internally between the electrodes to balance the electron flow and complete the circuit.

When charging a battery, an external power source applies a voltage that reverses the reaction, causing the electrons to flow back to the negative electrode and ions to resettle. This restores the battery to its charged state.

Primary Batteries

Primary batteries, also known as single-use or disposable batteries, are batteries that cannot be recharged. Some common examples include alkaline batteries and zinc-carbon batteries. Let’s look at the pros and cons of primary batteries:


  • Inexpensive – Primary batteries generally cost less than rechargeable batteries.
  • No recharging equipment needed – You don’t need any special equipment to recharge them.
  • Long shelf life – They retain most of their charge for up to 10 years if unused.
  • Simplicity – No need to worry about recharging, battery memory issues, etc.


  • Not reusable – Single use only, so they generate more waste.
  • Self-discharge – They slowly lose power even when not in use.
  • Miss out on recharging cost savings – Cost more in the long run vs. rechargeables.
  • Contain toxic materials – Alkaline batteries contain mercury, zinc-carbon batteries contain manganese dioxide and zinc chloride.

Overall, while primary batteries offer convenience for low-drain devices, their disposability and toxic contents make them less environmentally friendly. The costs also add up over time for devices with higher power demands.

Secondary Batteries

Secondary batteries, also known as rechargeable batteries, can be recharged multiple times by applying an external voltage. This reverts the electrochemical reaction and restores their charge. Common types of rechargeable batteries include nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lithium-ion (Li-ion), and lead-acid batteries. Here are the main pros and cons of secondary batteries:


  • Reusable – Can be recharged hundreds or thousands of times.
  • Cost effective – More affordable in the long run compared to disposables.
  • Eco-friendly – Require fewer batteries over lifetime so generate less waste.
  • Higher capacity – Provide more power than primaries before needing recharge.


  • Self-discharge – Gradually lose charge when idle.
  • Maintenance – May require periodic calibration or conditioning to maximize performance.
  • Recharging equipment – Need a specific charger or device with charging capabilities.
  • Recharging time – May take hours to fully recharge depending on battery capacity.

Overall, the reusability of secondary batteries makes them a better choice for the environment. Their higher capacity and long-term cost savings also make them better for high-drain devices. However, they require more maintenance and the right recharging equipment.

Comparison of Battery Types

Let’s directly compare some of the most common battery types.

Battery Type Composition Voltage Price Rechargeable?
Alkaline Zinc, manganese dioxide, potassium hydroxide 1.5V Cheap No
Lithium-Ion Lithium cobalt oxide, graphite 3.7V Moderate Yes
Lead-Acid Lead, lead oxide, sulfuric acid 2V Inexpensive Yes
Nickel-Cadmium Nickel oxide hydroxide, metallic cadmium 1.2V Moderate Yes

This comparison shows that alkaline batteries are very affordable and widely available, but must be replaced frequently. Meanwhile, rechargeable lithium-ion batteries offer higher voltage in a lightweight package, but cost more upfront. Lead-acid batteries are also very inexpensive for their energy capacity, but are very heavy. Nickel-cadmium batteries are moderately priced but contain toxic cadmium, making disposal difficult.

Environmental Impact

Now let’s take a detailed look at some of the environmental considerations of each battery type.

Alkaline Batteries

While alkaline batteries are affordable and convenient to use, there are several downsides to their environmental impact:

  • Contain mercury, zinc, and manganese – toxic if incinerated or leaked
  • Not accepted at many recycling centers due to mercury content
  • High rates of disposal since they are not rechargeable
  • Significant raw material usage since replaced frequently

On the positive side, alkaline batteries no longer contain mercury in many countries due to restrictions. However, they still present recycling challenges and generate more waste than rechargeable options.

Lithium-Ion Batteries

Lithium-ion batteries have some advantages and disadvantages when it comes to their environmental impact:

  • No toxic cadmium or mercury
  • Lower waste generation due to reusability
  • Moderately high recyclability due to valuable materials
  • Risk of fires and explosions if damaged, exposed to high temperatures, or improperly disposed
  • Difficult to recycle if multiple battery chemistries used in same device

Li-ion batteries reduce waste compared to disposables, but still need proper handling at end-of-life to maximize safe recyclability. New chemistries are also improving their stability and recyclability.

Lead-Acid Batteries

The lead content of lead-acid batteries causes some environmental concerns:

  • Lead and sulfuric acid are hazardous if leaked
  • Recycling rates are high due to lead value
  • Require proper disposal at end-of-life to recover materials

While the lead content raises safety considerations, lead-acid batteries have very high recycling rates, keeping their toxic contents out of landfills. Proper collection infrastructure is key to maintaining safe disposal.

Nickel-Cadmium Batteries

Nickel-cadmium batteries have faced bans and restrictions due to the toxic cadmium they contain:

  • Cadmium is toxic and carcinogenic if released into environment
  • Banned from consumer electronics in EU due to toxicity
  • Relatively high recyclability due to Ni and Cd reclamation
  • Being phased out in favor of nickel-metal hydride and lithium-ion batteries

While NiCd batteries are reliable and affordable, concerns over cadmium’s toxicity have led to declines in their use. New restrictions aim to phase them out in favor of more environmentally friendly chemistries.

Best and Worst Batteries for the Environment

Based on the previous sections comparing different battery types, here are our picks for the best and worst batteries in terms of their environmental impact:


  1. Lithium-Ion: No cadmium or mercury, lower waste generation, and moderately high recyclability make Li-ion one of the better options overall.
  2. Lead-Acid: Very high recycling rates minimize their toxic contents going to landfills.
  3. Nickel-Metal Hydride: No cadmium and excellent charge cycles make NiMH a good alternative to Li-ion where performance is important.


  1. Nickel-Cadmium: The extreme toxicity of cadmium has led to tight restrictions and phase-outs.
  2. Alkaline: Difficulty recycling and high disposal rates make these unsuitable for high-drain devices.
  3. Zinc-Carbon: Low performance and high waste generation make these a poor choice vs. rechargeable options.


In conclusion, while no battery type is perfect, rechargeable lithium-ion and nickel-metal hydride batteries offer the best combination of performance, safety, and eco-friendliness for most applications. Meanwhile, consumers should try to avoid nickel-cadmium and alkaline batteries where possible. Proper recycling is important for all battery types to recover materials and reduce toxicity risks.

As research continues, new battery technologies aim to further improve capacity, stability, cost-effectiveness, and environmental impact. In the future, batteries may rely on alternative chemistries using more abundant and benign materials. But for now, lithium-ion remains the top choice for many electronics and nickel-metal hydride serves as a good option for cost-sensitive applications. With proper end-of-life recycling, these technologies can help minimize the impact batteries have on the environment.