| 摘要 |
Disclosed is a metal gradient-doped cathode material for lithium ion batteries including a hexagonal-crystalline material body and a modifying metal. The metal gradient-doped cathode material is formed by coating modifying metal hydroxide on the surface of the hexagonal-crystalline material using a chemical co-precipitation method, then sintering the modifying metal hydroxide coated hexagonal-crystalline material. The modifying metal is different from the active metals, more concentrated on the surface, and gradually decreases toward the core of particle. A gradient-doped distribution is formed without any boundary or layered structure in the particle. The surface of the powder with more the modifying metal can effectively reduce the reactivity of the cathode material with the electrolyte in the lithium battery. Thus, the overall operation-stability and safety of lithium batteries are improved, and only a little amount of the modifying metal is needed, thereby avoiding the reduction of capacity and increasing the rate-capability and cycle-life. |
| 主权项 |
1. A metal gradient-doped cathode material served as a powder used for lithium batteries, comprising a hexagonal-crystalline material body and a modifying metal or metalloid, wherein the hexagonal-crystalline material body is doped with the modifying metal or metalloid in a gradient of concentration, the metal gradient-doped cathode material is specified by a chemical formula “f mol % M doped LizNiaCobMncO2”, LizNiaCobMncO2 represents the hexagonal-crystalline material body as an active component of cathode material, the hexagonal-crystalline material body comprises a lithium metal oxide of a single metal selected from Ni (nickel) and Co (cobalt), or two metals selected from Ni/Co, Ni/Mn (manganese) and Co/Mn, or three metals comprising Ni, Co and Mn, where z, a, b and c in the chemical formula are specified by 0.9≦z≦1.2, a+b+c=1, 0≦a≦1, 0≦b≦1 and 0≦c≦0.6, M represents the modifying metal or the metalloid comprising at least one of magnesium (Mg), calcium (Ca), strontium (Sr), boron (B), aluminum (Al), gallium (Ga), indium (In), titanium (Ti), silicon (Si) and tin (Sn), f indicates a molar content of the modifying metal or the metalloid, and is larger than 0.5% and smaller than 10% of a total molar content of Ni, Co and Mn in the hexagonal-crystalline material body, specified by 0.5% (a+b+c)≦f≦10% (a+b+c), and the metal gradient-doped cathode material is formed by coating modifying metal hydroxide on the surface of the hexagonal-crystalline material using a chemical co-precipitation method, then sintering the modifying metal hydroxide coated hexagonal-crystalline material. |
