A positive electrode for a lithium secondary battery includes a positive electrode current collector, a positive electrode active material layer, and a primer layer formed between the positive electrode current collector and the positive electrode active material layer. The primer layer includes lithium carbonate (Li.sub.2CO.sub.3) particles having two or more different particle diameters, a binder polymer, and a conductive material. The lithium secondary battery attains the overcharge cutoff voltage rapidly by virtue of the gas generated between the positive electrode current collector and the positive electrode active material layer, in an overcharged state. Thus, it is possible to ensure the safety of the lithium secondary battery.

A positive electrode for a lithium secondary battery includes a positive electrode current collector, a positive electrode active material layer, and a primer layer formed between the positive electrode current collector and the positive electrode active material layer. The primer layer includes lithium carbonate (Li.sub.2CO.sub.3) particles having two or more different particle diameters, a binder polymer, and a conductive material. The lithium secondary battery attains the overcharge cutoff voltage rapidly by virtue of the gas generated between the positive electrode current collector and the positive electrode active material layer, in an overcharged state. Thus, it is possible to ensure the safety of the lithium secondary battery.

The present disclosure provides a positive electrode additive and a preparation method thereof, a positive electrode plate and a lithium-ion secondary battery. The positive electrode additive comprises a modified lithium carbonate. The modified lithium carbonate comprises a lithium carbonate particle and a polymer coating. The polymer coating coats a surface of the lithium carbonate particle and comprises a polymer. The positive electrode additive of the present disclosure has low cost and simple preparation method, when the positive electrode additive is applied in lithium-ion secondary battery, it can significantly improve lithium-ion secondary battery safety performance without affecting electrical performance of the lithium-ion secondary battery.

The present disclosure provides a positive electrode additive and a preparation method thereof, a positive electrode plate and a lithium-ion secondary battery. The positive electrode additive comprises a modified lithium carbonate. The modified lithium carbonate comprises a lithium carbonate particle and a polymer coating. The polymer coating coats a surface of the lithium carbonate particle and comprises a polymer. The positive electrode additive of the present disclosure has low cost and simple preparation method, when the positive electrode additive is applied in lithium-ion secondary battery, it can significantly improve lithium-ion secondary battery safety performance without affecting electrical performance of the lithium-ion secondary battery.

A process is provided for recovering a heavy metal from a waste stream resulting from a process for producing aromatic carboxylic acid by liquid-phase oxidation of an aromatic feedstock compound in the presence of a heavy metal catalyst. The process comprises: (a) producing a carbonate salt precipitate of the heavy metal by adding a source of metal ions and carbonate or bicarbonate ions into the waste stream; (b) separating the precipitate from the waste stream; (c) washing the precipitate with an alkali solution having metal ions therein, wherein at least a portion of the metal ions in the alkali solution are the same as at least a portion of metal ions in the source of metal ions and carbonate or bicarbonate ions; and, (d) recovering the washed precipitate wherein the washed precipitate comprises the heavy metal ions. In one embodiment, the aromatic carboxylic acid comprises terephthalic acid.

A process is provided for recovering a heavy metal from a waste stream resulting from a process for producing aromatic carboxylic acid by liquid-phase oxidation of an aromatic feedstock compound in the presence of a heavy metal catalyst. The process comprises: (a) producing a carbonate salt precipitate of the heavy metal by adding a source of metal ions and carbonate or bicarbonate ions into the waste stream; (b) separating the precipitate from the waste stream; (c) washing the precipitate with an alkali solution having metal ions therein, wherein at least a portion of the metal ions in the alkali solution are the same as at least a portion of metal ions in the source of metal ions and carbonate or bicarbonate ions; and, (d) recovering the washed precipitate wherein the washed precipitate comprises the heavy metal ions. In one embodiment, the aromatic carboxylic acid comprises terephthalic acid.

A method for manufacturing a cobalt based hydroxide carbonate compound having a malachite-rosasite mineral structure, comprising the steps of: providing an first aqueous solution comprising a source of Co, providing a second aqueous solution comprising Na.sub.2CO.sub.3, mixing both solutions in a precipitation reactor at a temperature above 70 C., thereby precipitating a cobalt based hydroxide carbonate compound whilst evacuating from the reactor any CO.sub.2 formed by the precipitation reaction, wherein the residence time of the compound in the reactor is between 1 and 4 hours, andrecovering the cobalt based hydroxide carbonate compound. The cobalt based hydroxide carbonate compound is used as a precursor of a lithium cobalt based oxide usable as an active positive electrode material in lithium ion batteries.

A method for manufacturing a cobalt based hydroxide carbonate compound having a malachite-rosasite mineral structure, comprising the steps of: providing an first aqueous solution comprising a source of Co, providing a second aqueous solution comprising Na.sub.2CO.sub.3, mixing both solutions in a precipitation reactor at a temperature above 70 C., thereby precipitating a cobalt based hydroxide carbonate compound whilst evacuating from the reactor any CO.sub.2 formed by the precipitation reaction, wherein the residence time of the compound in the reactor is between 1 and 4 hours, and recovering the cobalt based hydroxide carbonate compound. The cobalt based hydroxide carbonate compound is used as a precursor of a lithium cobalt based oxide usable as an active positive electrode material in lithium ion batteries.

A cobalt based hydroxide carbonate precursor compound of a lithium cobalt based oxide, which is usable as an active positive electrode material in lithium ion batteries is described. The compound comprises a doped malachite-rosasite mineral structure and has a general formula [Co.sub.1-aA.sub.a].sub.2(OH).sub.2CO.sub.3, wherein A is one or more of Ni, Mn, Al, Ti, Zr and Mg, with a0.05.

Process for precipitating a carbonate or (oxy)hydroxide comprising nickel from an aqueous solution of a nickel salt wherein such process is carried out in a vessel comprising (A) a vessel body, (B) one or more elements that control the hydraulic flow of the slurry formed during the precipitation and that induce a loop-type circulation flow, and (C) a stirrer whose stirrer element is in the vessel but located separately from the element(s) (B).