1. High capacity
  2. High output voltage
  3. Low self-discharge
  4. long cycle life
  5. No memory effect
  6. No heavy metal, such as: cadmium and mercury; green battery, no pollution to the environment.
  7. light weight
The biggest characteristic of the lithium battery is specific energy, which refers to the energy per unit weight or unit volume and indicated with Wh/kg or Wh/L. Wh is a unit of energy; W is w; h means an hour; Kg is a kilogram (weight unit); L is the energy (Wh) for the storage of bulk batteries. Battery voltage(V) multiply electricity equals to battery energy. The max battery voltage is restricted by the electrolyte. For aqueous electrolyte battery, such as (alkaline manganese batteries, lead-acid batteries, nickel cadmium and nickel metal hydride batter), in theory, the electric potential is not higher than the decomposition voltage of water (1-2V). In the other hand, the decomposition voltage of organic electrolyte is much higher than the decomposition voltage of water solution, and the range of the selected voltage is 4-5V. Since lithium ion battery uses organic electrolyte, the voltage improves about 3 times higher than the capacity will be increased by 3 times, it belong s to a high voltage and high specific capacity battery.Generally, Lithium ion capacity density can reach 450WH/L,  which 3 times of cadmium nickel battery and 2 times of nickel metal hydride battery.
The voltage of single li ion battery can reach 3.6v to 3.8v, that is three times of NiCd or NiMH batterie.
Self discharge is the chemical energy loss caused by the spontaneous reaction of the battery when the battery is not connected with the outside world. Battery self discharge rate is the ratio of the initial capacity of the battery after storage for a period of time. Lithium ion battery self discharge rate is less than 10% per month, far less than 30% of nickel hydrogen battery, 15% of nickel cadmium battery.
Under common using conditions, lithium ion batteries can be ran 500 -2000 times, depending on different design.
  • Positive Materials 
  1. LiCoO2 is the first commercial use for positive material and also the most normal and largest consumption recently days. This material has the excellent electrochemical properties, such as first cycle irreversible, small capacity loss, high efficiency on charge and discharge, good thermal stability, long cycle life and 3.6v working voltage. But cobalt has higher cost and lacks of resource, in order to reduce the cost of battery, cheaper materials with little cobalt or no cobalt must to be developed.
  2. LiNiO2 has the good advantage in price and reserves, and its real capacity has been closed to 70-80% of the theoretical capacity. LiNiO2 has the excellent advantages of lower discharge rate, no environment pollution and lower requirements for electrolyte. But its initial discharge efficiency is just about 85%, in addition, thermal stability of battery may cause some safety problems. To achieve a better practical effect, the discharge and charge efficiency and thermal stability need to be improved. At the same time, production methods should be adapted to the requirements of industrial production.
  3. Lithium Manganese Oxide(LiMn2O4)

LiMn2O4 not only has advantage on price, but also has the advantage of good safety, no environment pollution, low toxicity and easy recovery, high working voltage and lower cost. The three-dimensional tunnel structure is more conducive to the intercalation and deintercalation of lithium ion battery than ratio of intercalation compounds. However, the compatibility of LiMn2O4 and electrolyte is not good, and the cycle life under high temperature and high voltage is also a problem. LiMn2O4 is the main research object and the most promising positive material for lithium ion batteries at present and in the future.

  • Negative Material

The key lies in the Negative Material can reversibly intercalate and deintercalate lithium ion. This kind of material should have the best possible low electrode voltage, the ion has the high diffusion rate, the high degree of reversibility, the good electrical conductivity and the thermodynamic stability. At present, carbon materials are mainly used in the Negative Material.

  1. Soft carbonThe arrangement of soft carbon layered structure is disordered, so it’s difficult to embed and deintercalate from Li ion. At the same time, due to the larger surface, forming more SEI layer, so there is a large irreversible capacity to loss. In addition, during the process of discharge, the voltage change is large.
  2.  Hard carbonHard carbon has a very high lithium intercalation capacity, but the vast majority of the lithium potential is 0V, so it is difficult to control the precipitation of metal lithium.

 

  • Electrolyte

Electrolyte is the carrier of lithium ion in the reaction process. In order to meet the requirements of lithium ion battery performance , the use of the lithium ion battery should meet the following requirements:

  1. The ionic conductivity of lithium ion conduction is as high as possible;
  2. The potential range of electrochemical stability is as wide as possible;
  3. Good thermal stability, the use of the temperature range as wide as possible;
  4. Good chemical stability, and collection of fluid inside battery and reactive substancesthe have no reaction;
  5. Good safety and low toxicity, it is best to biodegradable;
  6. Low price.
  • Separator 

Separator is between positive and negative electrodes, which is mainly to prevent the positive and negative electrode connect directly resulting the battery internal short circuit. Polyolefin porous film used in lithium ion batteries, the thickness is about 25um. The Performance requirements are:

 

  1. Good stability in the use of electrolytes;
  2. Do not absorb moisture;
  3. Have excellent insulation to the positive and negative electrode;
  4. Ionic conductivity;
  5. Enough mechanical strength;
  6. With the hot melt:When the temperature is about 130℃, the diaphragm has the function of organizing ion penetration and automatic termination of battery discharge. This function is very important for the safety of the battery.

Due to the above conditions, the most commonly used diaphragm is PP (polypropylene) /PE (polyethylene) bilayer microporous film.

  1.  Nominal voltage:the approximate value of the lithium ion battery voltage, which is 3.7V.
  2.  Nominal capacity:Used to identify approximate ampere hour capacity of lithium ion battery.
  3.  Rated capacity:At ambient temperature(20+5℃), capacity discharge to termination voltage at 5 hours,expressed by C5, unit is Ah or mAh.
  4. Charge:A progress of battery accepts the electric energy from the external circuit, and transformed into chemical energy.
  5.  Full charge:with 1C5mA constant current,battery charged to 4.2V, then constant voltage charge to current less than 0.01C5mA/.
  6. Discharge:the process of transferred chemical energy to electric energy, and output current.
  7.  Discharge termination voltage:At the end of the discharge, the specified voltage is 2.75V.
  8. Charge limit voltage:According to the manufacturer, battery is charged by the constant current and changes to the constant voltage, voltage is 4.2V.
  9. Platform:After fully charged, the time of 1C5mA constant current discharge to 3.6V.
  10.  Internal resistance: refers to the battery in the charging of 40-50%, by secondary battery internal resistance tester for measuring the internal resistance, represented by mΩ.
  11. Cycle:the process of Charging(discharging) and discharging(charging) under specified conditions.
  12. Working life:the validity of the battery life under specified conditions.
  13.  Self discharge:When battery is not connected with external circuit,Chemical energy loss due to spontaneous reaction of the battery.
  14. Charge holding capacity:The battery ability to maintain the load when circuit is open.
  15. Over-charge:continues to charge after full charge
  16.  Constant current charging:Continuous charge at constant current
  17. Constant Voltage charging:The voltage between the terminals of the battery is maintained at a constant value.
  18. Burst:refers to the internal pressure of battery, so that the internal structure fly out, or the battery shell in the design has been broken parts of the cracks and there is a flying object.
  19. Inflame:refers to the material spontaneous combustion inside the battery.