There are several important differences. The practical difference between Lithium batteries and Lithium-ion (Li-ion) batteries is that most Lithium batteries are not rechargeable but Li-ion batteries are rechargeable. From a chemical standpoint Lithium batteries use lithium in its pure metallic form. Li-ion batteries use lithium compounds which are much more stable than the elemental lithium used in lithium batteries. A lithium battery should never be recharged while lithium-ion batteries are designed to be recharged hundreds of times.
Lithium-ion batteries have several advantages:
They have a higher energy density than most other types of rechargeables. This means that for their size or weight they can store more energy than other rechargeable batteries. They also operate at higher voltages than other rechargeables, typically about 3.7 volts for lithium-ion vs. 1.2 volts for NiMH or NiCd. This means a single cell can often be used rather than multiple NiMH or NiCd cells.
Lithium-ion batteries also have a lower self discharge rate than other types of rechargeable batteries. This means that once they are charged they will retain their charge for a longer time than other types of rechargeable batteries. NiMH and NiCd batteries can lose anywhere from 1-5% of their charge per day, (depending on the storage temperature) even if they are not installed in a device. Lithium-ion batteries will retain most of their charge even after months of storage.
So in summary; lithium-ion batteries can be smaller or lighter, have a higher voltage and hold a charge much longer than other types of batteries.
Lithium-ion batteries are more expensive than similar capacity NiMH or NiCd batteries. This is because they are much more complex to manufacture. Li-ion batteries actually include special circuitry to protect the battery from damage due to overcharging or undercharging. They are also more expensive because they are manufactured in much smaller numbers than NiMH or NiCd batteries. Li-ion batteries are becoming less expensive and over time we should see their price decrease significantly.
Lithium ion batteries are not available in standard cells sizes (AA, C and D) like NiMH and NiCd batteries.
UPDATE: I just discovered an overseas manufacturer that sells down regulated li-ion cells in several standard cell configurations, AA, AAA, etc. that outputs 1.5 VOLT S - whaatttt?? How long have they been on the market? Are they reliable? Are they safe? Kentli is their name and I need to get some samples and test the heck out of them ASAP. Lithium ion is considered a "volatile" cell chemistry so I am a bit skeptical but finally a manufacturer has gone and ventured into that territory. This could be both disruptive and awesome. More to come. ;-)
Lithium-ion batteries also require sophisticated chargers that can carefully monitor the charge process. And because of their different shapes and sizes each type of Li-ion battery requires a charger designed to accommodate its particular size. This means lithium ion battery chargers are more expensive and more difficult to find than NiMH and NiCd battery chargers.
No, Lithium-ion batteries are not available in standard sizes. We believe this is because it would be too easy for users to inadvertently put them in a charger not designed for Lithium-ion batteries creating a potentially dangerous situation. (If an alkaline battery is put into the wrong charger it might leak or even burst, but a lithium-ion battery put into a NiCd or NiMH charger not designed for lithium-ion, might ignite. Also, because Li-ion batteries operate at much higher voltage (typically 3.7V per cell) than the 1.2 to 1.5V of most cell batteries, designing a 1.5V lithium-ion cell would be expensive.
Like prescription drugs there is often very little difference between name brand lithium-ion batteries and generic lithium-ion batteries. Camera makers often make very little from the sale of the camera itself, but have high profit margins for the accessories, like batteries and flashes. Not all third party batteries are the same quality as the original battery, but many (including those which we sell) are virtually identical.
Lithium-ion batteries can hold a charge for many months. It is best to store a lithium-ion battery with a partial or full charge. Occasionally, a lithium-ion battery with a very low charge is stored for a long period of time (many months) and its voltage slowly drops to below the level at which its built in safety mechanism allows it to be charged again. If the battery is going to be stored for several months it's a good idea to take it out and recharge it after a few months. Better yet would be to actually use the battery every few months and then leave it partially or fully charged.
The answer depends on the particular camera or device. But in many cases you can not. Because the size, shape and voltage of alkaline and lithium ion batteries are different they are not interchangeable. However, some camera makers have designed some of their cameras in a way that allows the camera to work with either AA size batteries or CRV3 type lithium batteries. If your camera or other device can use different types (chemistries) of batteries the User's Manual should mention it. Also check here to see if your camera can use the rechargeable CRV3 batteries that we carry. Important - There are several different kinds of rechargeable CRV3 lithium ion batteries now available under various brands and they cannot use each others chargers - they are designed as a set and have different charging requirements. This is one area, unlike NiCD and NiMH batteries that you need to get one brand of rechargeable battery, and its matching charger, and stick with it.
Another alternative would be to use an external battery pack of some sort. These are sometimes available with Lithium-ion batteries.
Normally you can not switch between a NiMH or NiCd battery and a lithium ion battery in a digital camera. There are some devices specifically designed to use either type of battery, cell phones are the most common example. If you can use either type of battery, it should say so in the User's Manual.
Lithium ion batteries, like all rechargeable batteries are recyclable and should be recycled. They should never be incinerated since they might explode. Most places that sell rechargeable batteries will also accept them back for recycling.