A lithium-containing silicon oxide composite anode material has a core-shell structure which includes a core and a shell. The core includes nano-silicon, Li.sub.2SiO.sub.3 and Li.sub.2Si.sub.2O.sub.5, and the shell is a conductive carbon layer wrapping the core. The invention provides a lithium-containing silicon oxide composite anode material which is able to maximize the reversible capacity and has a long cycle life, and a lithium ion battery containing the lithium-containing silicon oxide composite anode material. The invention further provides a method for preparing a lithium-containing silicon oxide composite anode material, which is simple in process, environmentally friendly and free of pollution.

A process for electrochemical preparation of sodium alkoxide is performed in an electrolysis cell having three chambers, wherein the middle chamber is separated from the cathode chamber by a solid-state electrolyte permeable to sodium ions, and from the anode chamber by a diffusion barrier. The geometry of the electrolysis cell protects the solid-state electrolyte permeable to sodium ions from acidic destruction by the pH of the anolyte that falls in the course of electrolysis. The anolyte used in the process is a brine also comprising carbonates and/or hydrogencarbonates, as well as NaCl. The process solves the problem that CO.sub.2 from these carbonates and/or hydrogencarbonates forms in the electrolysis cell during the electrolysis of this brine obtained from pretreatment. The process prevents the formation of a gas bubble in the electrolysis cell that disrupts electrolysis and reduces the contamination of the chlorine with CO.sub.2.

A process for electrochemical preparation of sodium alkoxide is performed in an electrolysis cell having three chambers, wherein the middle chamber is separated from the cathode chamber by a solid-state electrolyte permeable to sodium ions, and from the anode chamber by a diffusion barrier. The geometry of the electrolysis cell protects the solid-state electrolyte permeable to sodium ions from acidic destruction by the pH of the anolyte that falls in the course of electrolysis. The anolyte used in the process is a brine also comprising carbonates and/or hydrogencarbonates, as well as NaCl. The process solves the problem that CO.sub.2 from these carbonates and/or hydrogencarbonates forms in the electrolysis cell during the electrolysis of this brine obtained from pretreatment. The process prevents the formation of a gas bubble in the electrolysis cell that disrupts electrolysis and reduces the contamination of the chlorine with CO.sub.2.

A negative electrode active material including a core, an intermediate layer on a surface of the core, and a shell layer on a surface of the intermediate layer, wherein the core includes a silicon oxide of SiO.sub.x (0<x<2); the intermediate layer includes a lithium silicate, the shell layer includes lithium fluoride (LiF) and the intermediate layer is present in an amount of 5 wt %-15 wt % based on a total weight of the negative electrode active material. Also, a method for preparing the negative electrode active material, and a negative electrode and lithium secondary battery including the same. The negative electrode active material provides excellent initial efficiency and life characteristics.

A negative electrode including a negative electrode active material layer including a negative electrode active material including a negative electrode active material particle. The negative electrode active material particle includes a silicon compound particle including a silicon compound (SiOx: 0.5≤x≤1.6). The silicon compound particle includes crystalline Li2SiO3 in at least part of the silicon compound particle. Among a peak intensity A derived from Li2SiO3, a peak intensity B derived from Si, a peak intensity C derived from Li2Si2O5, and a peak intensity D derived from SiO2 which are obtained from a 29Si-MAS-NMR spectrum of the silicon compound particle, the peak intensity A is the highest intensity, and the peak intensity A and the peak intensity C satisfy a relationship of the following formula 1:
Formula 1: 3C<A.

A negative electrode including a negative electrode active material layer including a negative electrode active material including a negative electrode active material particle. The negative electrode active material particle includes a silicon compound particle including a silicon compound (SiOx: 0.5≤x≤1.6). The silicon compound particle includes crystalline Li2SiO3 in at least part of the silicon compound particle. Among a peak intensity A derived from Li2SiO3, a peak intensity B derived from Si, a peak intensity C derived from Li2Si2O5, and a peak intensity D derived from SiO2 which are obtained from a 29Si-MAS-NMR spectrum of the silicon compound particle, the peak intensity A is the highest intensity, and the peak intensity A and the peak intensity C satisfy a relationship of the following formula 1:
Formula 1: 3C<A.

A positive electrode active substance for a secondary cell, where the positive electrode active substance is capable of suppressing adsorption of water effectively in order to obtain a high-performance lithium ion secondary cell or sodium ion secondary cell. The positive electrode active substance contains 0.3 to 5 mass % of graphite, 0.1 to 4 mass % of carbon obtained by carbonizing a water-soluble carbon material, or 0.1 to 5 mass % of a metal fluoride is supported on a composite containing a compound which contains at least iron or manganese, where the compound is represented by formula (A) LiFe.sub.aMn.sub.bM.sub.cPO.sub.4, formula (B) Li.sub.2Fe.sub.dMn.sub.eN.sub.fSiO.sub.4, or formula (C) NaFe.sub.gMn.sub.hQ.sub.iPO.sub.4, and carbon obtained by carbonizing a cellulose nanofiber.

A positive electrode active substance for a secondary cell, where the positive electrode active substance is capable of suppressing adsorption of water effectively in order to obtain a high-performance lithium ion secondary cell or sodium ion secondary cell. The positive electrode active substance contains 0.3 to 5 mass % of graphite, 0.1 to 4 mass % of carbon obtained by carbonizing a water-soluble carbon material, or 0.1 to 5 mass % of a metal fluoride is supported on a composite containing a compound which contains at least iron or manganese, where the compound is represented by formula (A) LiFe.sub.aMn.sub.bM.sub.cPO.sub.4, formula (B) Li.sub.2Fe.sub.dMn.sub.eN.sub.fSiO.sub.4, or formula (C) NaFe.sub.gMn.sub.hQ.sub.iPO.sub.4, and carbon obtained by carbonizing a cellulose nanofiber.

A negative electrode active material for a secondary battery includes a lithium silicate phase, and a silicon phase dispersed in the lithium silicate phase. An electron diffraction image of the negative electrode active material obtained using a transmission electron microscope has a spot image, and an average particle diameter of the negative electrode active material is 8 μm or less.

A negative electrode active material for a secondary battery includes a lithium silicate phase; and a silicon phase dispersed in the lithium silicate phase. The lithium silicate phase contains at least one element M selected from the group consisting of alkali metals (except lithium), Group II elements, rare-earth elements, zirconium (Zr), niobium (Nb), tantalum (Ta), vanadium (V), titanium (Ti), phosphorus (P), bismuth (Bi), zinc (Zn), tin (Sn), lead (Pb), antimony (Sb), cobalt (Co), fluorine (F), tungsten (W), aluminum (Al), and boron (B). An electron diffraction image of the negative electrode active material obtained using a transmission electron microscope has a spot image.