The present invention provides a positive-electrode active material for a lithium-ion secondary cell or a sodium-ion secondary cell, which can effectively exhibit more excellent charge/discharge characteristics; and a method for manufacturing the positive-electrode active material. Namely, the present invention relates to a positive-electrode active material for a secondary cell comprising an oxide represented by formula (A): LiFe.sub.aMn.sub.bM.sub.cPO.sub.4, formula (B): LiFe.sub.aMn.sub.bM.sub.cSiO.sub.4, or formula (C): NaFe.sub.gMn.sub.hQ.sub.iPO.sub.4; and carbon derived from a cellulose nanofiber supported thereon.

The present invention provides a positive-electrode active material for a lithium-ion secondary cell or a sodium-ion secondary cell, which can effectively exhibit more excellent charge/discharge characteristics; and a method for manufacturing the positive-electrode active material. Namely, the present invention relates to a positive-electrode active material for a secondary cell comprising an oxide represented by formula (A): LiFe.sub.aMn.sub.bM.sub.cPO.sub.4, formula (B): LiFe.sub.aMn.sub.bM.sub.cSiO.sub.4, or formula (C): NaFe.sub.gMn.sub.hQ.sub.iPO.sub.4; and carbon derived from a cellulose nanofiber supported thereon.

An object is to provide an adsorbent using activated carbon fiber, the adsorbent being suitable for motor vehicle canisters and enabling reduction in pressure loss.

An activated carbon fiber sheet for a motor vehicle canister fulfils the following conditions (1) to (4). (1) The sheet has a specific surface area ranging from 1100 to 2300 m.sup.2/g. (2) The sheet has a density ranging from 0.010 to 0.200 g/cm.sup.3 or less. (3) The sheet has a thickness ranging from 0.1 to 100.00 mm. (4) The sheet has a fiber size of 13.0 μm or larger.

An object is to provide an adsorbent using activated carbon fiber, the adsorbent being suitable for motor vehicle canisters and enabling reduction in pressure loss.

An activated carbon fiber sheet for a motor vehicle canister fulfils the following conditions (1) to (4). (1) The sheet has a specific surface area ranging from 1100 to 2300 m.sup.2/g. (2) The sheet has a density ranging from 0.010 to 0.200 g/cm.sup.3 or less. (3) The sheet has a thickness ranging from 0.1 to 100.00 mm. (4) The sheet has a fiber size of 13.0 μm or larger.

A manufacturing method of a porous carbon composite material includes the following steps. A polymer template is provided, the polymer template includes a polymer compound, and the polymer template has a plurality of pores. A coating step is performed, wherein a metal compound is coated on the polymer template to form a transition intermediate. A heating step is performed, wherein the transition intermediate is heated to transform the polymer template to a carbon template and transform the metal compound to a coating layer, and a porous carbon composite material is obtained.

Cellulose-nanofiber carbon which can achieve a large specific surface area, and a method of producing the same are provided. The method for heat treating a cellulose nanofiber for carbonization includes: a freezing step of freezing a solution or gel containing the cellulose nanofiber to obtain a frozen product a drying step of drying the frozen product in a vacuum to obtain a dried product and a carbonizing step of heating and carbonizing the dried product in an atmosphere which does not burn the dried product to obtain the cellulose-nanofiber carbon.

Cellulose-nanofiber carbon which can achieve a large specific surface area, and a method of producing the same are provided. The method for heat treating a cellulose nanofiber for carbonization includes: a freezing step of freezing a solution or gel containing the cellulose nanofiber to obtain a frozen product a drying step of drying the frozen product in a vacuum to obtain a dried product and a carbonizing step of heating and carbonizing the dried product in an atmosphere which does not burn the dried product to obtain the cellulose-nanofiber carbon.

The present invention relates to a process for the production of asymmetric cellulose hollow fibres and the use of such fibres in the production of asymmetric carbon hollow fibre membranes (CHFMs). In particular, the present invention provides a facile and scalable process for the preparation of asymmetric CHFMs by direct pyrolysis of polymeric precursors without the need for complex pre-pyrolysis treatment steps to prevent pore collapse. The present invention also relates to the use of asymmetric CHFMs prepared according to said process in the separation of hydrogen gas from a mixed gas source, especially in the separation of hydrogen from CO.sub.2 in the steam-methane reforming reaction.

The present invention relates to a process for the production of asymmetric cellulose hollow fibres and the use of such fibres in the production of asymmetric carbon hollow fibre membranes (CHFMs). In particular, the present invention provides a facile and scalable process for the preparation of asymmetric CHFMs by direct pyrolysis of polymeric precursors without the need for complex pre-pyrolysis treatment steps to prevent pore collapse. The present invention also relates to the use of asymmetric CHFMs prepared according to said process in the separation of hydrogen gas from a mixed gas source, especially in the separation of hydrogen from CO.sub.2 in the steam-methane reforming reaction.

A process for stabilizing precursor fibers for the production of carbon fibers is disclosed. The process comprises the following steps: continuously introducing, passing and removing said precursor fibers into, through and from a process chamber; establishing a predetermined process gas atmosphere different in composition from ambient air in said at least one process chamber, said process gas atmosphere containing at least one of a reactive component and a catalyst having a predetermined partial pressure; while said precursor fibers are in said process chamber, heating the precursor fibers to at least a first temperature and maintaining said first temperature for a predetermined period of time.