Sony announced that it will use tin (Sn) negative electrode material to improve the capacity of lithium-ion rechargeable battery. The development of the “18650″ size (diameter 18mm × high 65mm) of the cell, the capacity of up to 3.5Ah. With the company in 2010 compared to the original production of 2.8Ah capacity significantly increased by 25%. Scheduled to begin shipping during the year 2011.
In fact, this is not the first time that the negative use of Sony lithium-ion rechargeable battery of Sn of their products. The company started in 2005 for the camera from the sale of the diameter of 14mm × 43mm high, “14430″ size battery cells. The laptop will be in volume production for a large circle of more than 14430 18650 size products.
The development of lithium-ion rechargeable battery has a positive and improved diaphragm. The cathode material by the capacity and safety of both the ternary class (Li (Ni-Co-Mn) O2) material into a lithium cobalt oxide (LiCoO2). Co in LiCoO2 material prices higher, and thermal stability at a disadvantage, so the cathode material has been directed triple class changes, but Sony was against the tide, using a higher capacity of the LiCoO2.
LiCoO2 in an internal short circuit or other abnormal temperature rise, this case will produce oxygen, oxygen reacts with the organic electrolyte may burn. Therefore, Sony LiCoO2 particle surface “in the 0.1 ~ 1μm thick coating process” (Inoue). According to the company, this approach can reduce the reaction of oxygen with organic electrolyte.
Diaphragm, in order to prevent internal short circuit, micro-porous polyolefin membrane in the formation of a few μm thick on both sides of the metal oxide ceramic layer (Figure 3). Ceramic layer with three-dimensional structure, the diameter of the metal oxide particles less than 1μm and a mesh-like adhesive resin was connected. When an exception occurs, the higher flexibility and adhesive resin network that allows insulation around the metal oxide attached to the foreign body, thus limiting the current through.
Membrane on both sides to form a three-dimensional structural ceramic layer. Once mixed with metal foreign bodies cause membrane damage, ceramic layer will transfer to the surface of metallic foreign body to prevent a large current through. (Figure from “Nikkei Electronics,” according to information drawn Sony)
Of course, the new unit there are also issues. For example, the repeated charge and discharge 300 times after the initial capacity will be reduced to about 80%. After repeated charge-discharge capacity of 500 will be reduced to about 60%, available only managed to reach the minimum standards used in notebook computers.
