The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from c...The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from carbonates can be divided into two steps. Below 300℃cobalt carbonate and/or nickel carbonate decompose forming oxides. Over 300℃ Li2CO3 decomposes and reacts with Co and/or Ni oxides gradually, as a result Co++ and/or Ni++ areoxidized to Co+++ and/or Ni+++, finally LiCo1-xNixO2 forms. The proportion of cobalt tonickel in the starting mixture and atmosphere during synthesis affects the structure of products.LiCo1-xNixO2(x≤0.5) can be synthesized in air or oxygen and characterized by solid solutionof LiCoO2 and LiNiO2. LiNiO2 can be obtained only from hydrates and in oxygen atmosphere.LiNiOz and LiCo0.5Ni0.5O2 have higher first charge capacity than that of LiCoO2. Their discharge capacity reaches a level with that of LiCoO2 and has reasonable reversibility.展开更多
In this paper, we shall study the initial boundary value problem of Schrodinger equation. The second order gradient superconvergence estimates for the problem are obtained solving by linear finite elements.
For the first order nonstationary hyperbolic equation taking the piecewise linear discontinuous Galerkin solver, we prove that under the uniform rectangular partition, such a discontinuous solver, after postprossesing...For the first order nonstationary hyperbolic equation taking the piecewise linear discontinuous Galerkin solver, we prove that under the uniform rectangular partition, such a discontinuous solver, after postprossesing, can have two and half approximative order which is half order higher than the optimal estimate by Lesaint and Raviart under the rectangular partition.展开更多
In this paper, the Wilson nonconforming finite element is considered for solving a class of second-order elliptic boundary value problems. Based on an asymptotic error expansion for the Wilson finite element, the glob...In this paper, the Wilson nonconforming finite element is considered for solving a class of second-order elliptic boundary value problems. Based on an asymptotic error expansion for the Wilson finite element, the global superconvergences, the local superconvergences and the defect correction schemes are presented.展开更多
This paper deals with Raviart-Thomas element (Q(2,1) x Q(1,2) - Q(1) element). Apart from its global superconvergence property of fourth order, we prove that a postprocessed extrapolation can globally increased the ac...This paper deals with Raviart-Thomas element (Q(2,1) x Q(1,2) - Q(1) element). Apart from its global superconvergence property of fourth order, we prove that a postprocessed extrapolation can globally increased the accuracy by fifth order.展开更多
文摘The mechanism of LiCo1－xNixO2(x=0, 0.5, 1) synthesis from carbonates or hydrates was studied by thermogravimetric analysis and X-ray diffraction to identify the medium and final products. The synthesis process from carbonates can be divided into two steps. Below 300℃cobalt carbonate and/or nickel carbonate decompose forming oxides. Over 300℃ Li2CO3 decomposes and reacts with Co and/or Ni oxides gradually, as a result Co++ and/or Ni++ areoxidized to Co+++ and/or Ni+++, finally LiCo1-xNixO2 forms. The proportion of cobalt tonickel in the starting mixture and atmosphere during synthesis affects the structure of products.LiCo1-xNixO2(x≤0.5) can be synthesized in air or oxygen and characterized by solid solutionof LiCoO2 and LiNiO2. LiNiO2 can be obtained only from hydrates and in oxygen atmosphere.LiNiOz and LiCo0.5Ni0.5O2 have higher first charge capacity than that of LiCoO2. Their discharge capacity reaches a level with that of LiCoO2 and has reasonable reversibility.
文摘In this paper, we shall study the initial boundary value problem of Schrodinger equation. The second order gradient superconvergence estimates for the problem are obtained solving by linear finite elements.
基金Subsidized by the Special Funds for Major State Basic Research Projects G1999032804.
文摘For the first order nonstationary hyperbolic equation taking the piecewise linear discontinuous Galerkin solver, we prove that under the uniform rectangular partition, such a discontinuous solver, after postprossesing, can have two and half approximative order which is half order higher than the optimal estimate by Lesaint and Raviart under the rectangular partition.
文摘In this paper, the Wilson nonconforming finite element is considered for solving a class of second-order elliptic boundary value problems. Based on an asymptotic error expansion for the Wilson finite element, the global superconvergences, the local superconvergences and the defect correction schemes are presented.
文摘This paper deals with Raviart-Thomas element (Q(2,1) x Q(1,2) - Q(1) element). Apart from its global superconvergence property of fourth order, we prove that a postprocessed extrapolation can globally increased the accuracy by fifth order.
