The present invention provides materials for negative electrodes of lithium rechargeable batteries. These materials include lithium alloy composites. Each lithium alloy composite has a core-shell structure with one or more lithium alloy granules as its core and a carbon material as its shell. The average granule diameter of said lithium alloy granule is between 5 .mu.m and 40 .mu.m. The average thickness of the shell layer is between 50 .ANG. and 1000 .ANG.. The average diameter of said lithium alloy composite is between 10 .mu.m to 50 .mu.m. The methods of fabrication for said material includes the following steps: stirring lithium alloy granules in an organic solution with a coating substance, drying the solid product in said organic solution with a coating substance, calcining the dried product to obtain the negative electrode material with lithium alloy composites. The lithium alloy composites fabricated in this manner have lithium alloy granules as a core coated with a shell of carbon material. Lithium ion rechargeable batteries with a negative electrode of this invention or fabricated by the methods of this invention have excellent initial charge-discharge efficiency, battery capacity and cycle life.
The present invention discloses negative electrodes for alkaline storage batteries and their methods of fabrication. The material for said negative electrode comprises of an additive that has at least one calcium compound selected from the following: tricalcium silicate, dicalcium silicate, and tricalcium aluminate. The concentration of said additive is between 1 wt % and 15 wt % of the material of said negative electrode. To fabricate said negative electrode, said additive is mixed with an active material for the negative electrode to form a paste, which is then dried. This method of fabrication is simple, convenient and low in cost. An alkaline battery using said material for its negative electrode has long cycle life and a large capacity.
The present invention discloses positive electrodes and their methods of fabrication. These electrodes are low in cost. Lithium rechargeable batteries that use these positive electrodes have excellent cycling properties at high temperature. The positive electrode of the embodiments of this invention comprises of a current collector coated by two layers of active materials for positive electrodes. The active material for the first layer of coating is one or more active materials selected from the following: spinel lithium manganese oxide, and spinel lithium manganese oxide derivatives. The active material for the second layer of coating is one or more active material selected from the following: lithium cobalt oxide, lithium cobalt oxide derivatives, lithium nickel oxide, and lithium nickel oxide derivatives. To fabricate these positive electrodes, a first layer of coating comprising of the active materials stated above is applied onto a current collector and then dried before a second layer of coating is applied onto the surface of the first layer of coating. The positive electrode is obtained after the current collector with the two layers of coating is dried a second time and then pressed to form a slice.
A type of lithium ion secondary battery is disclosed; therein, the positive electrode 1 is formed by smearing an active material on the surface of an aluminum foil body, where said active material is compound oxide(s) comprising transition metals and lithium capable of absorbing and releasing lithium ions; the negative electrode 2 is formed by smearing an active material on the surface of a copper foil body, where said active material includes carbon material capable of absorbing and releasing lithium ions. Both the positive and negative electrodes have conducting strips acting as current conductors 6, 7. The positive and negative electrodes 1, 2 are in plate form and are alternately stacked on both sides of the belt-shaped separator 3 to form the electrode core 4. The separator 3 wraps around said electrode plates and separates the positive and negative electrodes 1, 2. This type of lithium ion secondary battery can effectively use the internal space of a battery shell, increase the battery's energy density, improve the large current discharge characteristic of the lithium ion secondary battery, the self-discharge ability, the battery's cycling capability and the battery's capacity.