니켈 충전지, nickel rechargeable batteries

니켈 카드뮴 전지(Ni-Cd, 니카드)는 일상생활에서 접할 수 있는 2차 전지의 주류를 차지한 적이 있었으나 지금은 저용량에 중금속에 의한 환경문제 때문에 건전지가 대체할 수 있는 AA, AAA 사이즈급에서는 거의 사장된 상태이며 UPS나 일부 실내 무선전화기에나 쓰이는 정도다. 2021년 현재 AA, AAA 사이즈의 니켈 카드뮴 전지는 드물고 배터리팩 상태로 주로 팔린다. 물론 굳이 AA 사이즈를 구하겠다면 팩을 사서 분해하면 된다.

니켈 카드뮴 전지는 납 축전지에 이어 두번째로 발명된 이차 전지이다. 1899년에 발명됐다.

빌딩의 비상대피로 유도등 안에는 니켈카드뮴 전지가 조명용으로 들어간다. 한번 충전해 놓고 오랜 시간 사용하지 않고 버티다가 언제 올지 모르는 정전 시 비상유도 등에 불을 켜는 용도로서는 알카라인보다는 니카드 전지가 최적이다.

물론 세방전지나 이런 쪽에서는 AA 니카드 전지가 나오곤 있는데, 이는 일반 유저를 겨냥한 제품은 절대 아니다. 1/5에 불과한 초 저용량의 전지를 쓰고자 하는 사람이 얼마나 있겠는가. 하지만 니카드 전지의 가장 큰 특징은 니카드 전지 특유의 놀라운 안정성과 상당히 높은 방전률에 기인한다. 니켈 수소 전지에 비해 델타피크가 깔끔하게 뜨고, 그 이후 전류가 흐르지 않아 충전회로가 간단한 것은 많은 비상조명 시장에서의 선택으로 증명됐고, -30℃의 혹한에서도 제 용량을 보이며 고율방전이 가능한 점은 전문 사용자 입장에서는 매우 높은 이점을 가지고 있다. 그 덕에 지금 나오는 니카드 전지는 과거 방식에 현재의 첨단 기술이 들어간 형태로, 가격이 니켈 수소랑 비슷하다 보니 특정 전문분야 외에는 잘 안 팔린다. 물론 그래도 전국적인 수요를 보면 나름 스테디셀러.

니켈 수소 전지(Ni-MH, Nickel-Metal Hydride)는 2000년대 중반까지 인기가 있었다. 기존의 니켈 카드뮴 전지에 비해 고용량이었기 때문. 카세트테이프 플레이어와 휴대용 CD 플레이어 등에 필수로 쓰이던 사각형의 충전지(일명 껌전지)가 니켈 수소 전지이기도 했으며 이후 보급된 MP3 플레이어와 컴팩트형 디지털 카메라(이른바 똑딱이)의 대부분이 전용 리튬 이온이 아닌 일반 전지로 구동됐기에 니켈 수소 전지가 주목받았던 점이 있었다. 이후 MP3 플레이어의 배터리도 내장형으로 바뀌었고 디지털 카메라의 배터리들도 상당수가 전용 배터리로 바뀌면서 수요가 많이 줄어들었다. 외부 배터리를 써야 하는 경우 아직 많이 쓰인다. 특히 고 성능의 제품에 경우 금방 방전이 되기 때문에, 일회용품인 알카라인 건전지에 비해 경제적이며 친환경적이라는 장점도 있다. 이케아의 경우 폐건전지를 줄이기 위해 알카라인 전지 판매를 중단하고 재충전 가능한 니켈 수소 전지만 판매하고 있다. 하이브리드 자동차의 구형 모델은 니켈 충전지가 아직도 쓰이고 있다.

이외에도 니켈 철, 니켈 아연 등 다른 종류의 니켈 기반 이차 전지도 존재하나 니켈 카드뮴/니켈 수소보다 성능이 떨어지는 관계로 흔히 쓰이지는 않는 편이다.

 

 

 

Nickel cadmium batteries (Ni-Cd, Ni-Cd) used to be the mainstream of secondary batteries that can be encountered in everyday life, but they are almost dead in AA and AAA sizes, which can be replaced by batteries due to environmental problems caused by low capacity and heavy metals, and are only used in UPS and some indoor wireless phones. As of 2021, nickel cadmium batteries in sizes AA and AAA are rare and sold mainly in battery packs. Of course, if you want to get a size AA, you can buy a pack and disassemble it.

The nickel cadmium battery is the second secondary battery to be invented after lead storage batteries. It was invented in 1899.

Nickel-cadmium batteries are used for lighting inside the induction light for emergency evacuation. Ni-cad batteries are better suited than alkaline batteries to light emergency induction lights when a power outage occurs.

Of course, three-way batteries or AA Nikkad batteries are frequently produced in this area, but they are not intended for general users. How many people would want to use ultra-low-capacity batteries that are only 1/5th of that. However, the Nikkad battery's unique stability and fairly high discharge rate are the biggest features of the Nikkad battery. The simple charging circuit has been proven to be a choice in many emergency lighting markets because the delta peak rises neatly compared to the nickel hydrogen battery, and the ability to discharge at a high rate is very high from a professional user's point of view. As a result, the current advanced technology is used in the past, and because of that, it is similar in price to nickel hydrogen, it does not sell well outside of a specific specialized field. Of course, it is a steady seller in terms of national demand.

Nickel-Metal Hydride (Ni-MH) was popular until the mid-2000s. It was higher in capacity than conventional nickel-cadmium batteries. Nickel-hydrogen batteries were notable because rectangular rechargeable batteries (also known as gum cells), which were essential for cassette tape players and portable CD players, were also nickel-hydrogen batteries, and most of the MP3 players and compact digital cameras (so-called ticks) were powered by regular batteries rather than dedicated lithium ions. Since then, batteries for MP3 players have also been replaced with built-in batteries, and many batteries for digital cameras have been replaced with dedicated batteries, which has greatly reduced demand. They are still widely used when external batteries are needed. High-performance batteries, in particular, can be discharged quickly, making them more economical and eco-friendly compared to disposable alkaline batteries. IKEA has stopped selling alkaline batteries to reduce waste batteries and sells only rechargeable nickel-hydrogen batteries. Older models of hybrid cars still use nickel rechargeable batteries.

In addition, other types of nickel-based secondary batteries such as nickel iron, nickel zinc, and the like exist, but they are not commonly used because their performance is lower than that of nickel cadmium/nickel hydrogen.