Lithium-ion batteries have gained widespread use in consumer electronics due to their high energy density and low weight. However, for electric vehicle applications, further improvements in capacity and safety are highly challenging but necessary for lowering the cost and extending the driving distance. Materials with high lithium storage capacity, such as silicon and tin based alloys, have recently been extensively studied for their potential applications as Lithium battery anodes. But the large-volume change associated with lithiation and delithiation severely hinders the practical employments. [1][2][3][4][5][6][7] Despite the intensive efforts, [6][7][8][9][10][11][12] an effective low-cost solution to the volume-change problem remains elusive.Here, we developed a new conductive polymer through a combination of material synthesis,x-ray spectroscopy, density functional theory, and battery cell testing. Contrasting other polymer binders, the tailored electronic structure of the new polymer enables lithium doping under the battery environment. The polymer thus maintains both electric conductivity and

The dilemma of employing high-capacity battery materials and maintaining the electronic and mechanical integrity of electrodes demands novel designs of binder systems. Here, we developed a binder polymer with multi-functionality to maintain high electronic conductivity, mechanical adhesion, ductility, and electrolyte uptake. These critical properties are achieved by designing polymers with proper functional groups. Through synthesis, spectroscopy and simulation, electronic conductivity is optimized by tailoring the key electronic state, which is not disturbed by further modifications of side chains. This fundamental allows separated optimization of the mechanical and swelling properties without detrimental effect on electronic property. Remaining electrically conductive, the enhanced polarity of the polymer greatly improves the adhesion, ductility, and more importantly, the electrolyte uptake to the levels of those available only in non-conductive binders before. We also demonstrate directly the performance of the developed conductive binder by achieving full-capacity cycling of silicon particles without using any conductive additive.3

Electronic structure of disordered semiconducting conjugated polymers was studied. Atomic structure was found from a classical molecular dynamics simulation and the charge patching method was used to calculate the electronic structure with the accuracy similar to the one of density functional theory in local density approximation. The total density of states, the local density of states at different points in the system and the wavefunctions of several states around the gap were calculated in the case of poly(3-hexylthiophene) (P3HT) and polythiophene (PT) systems to gain insight into the origin of disorder in the system, the degree of carrier localization and the role of chain interactions. The results indicated that disorder in the electronic structure of alkyl substituted polythiophenes comes from disorder in the conformation of individual chains, while in the case of polythiophene there is an additional contribution due to disorder in the electronic coupling between the chains. Each of the first several wavefunctions in the conduction and valence band of P3HT is localized over several rings of a single chain.It was shown that the localization can be caused in principle both by ring torsions and chain bending, however the effect of ring torsions is much stronger. PT wavefunctions are more complicated due to larger interchain electronic coupling and are not necessarily localized on a single chain.

We developed an ab-initio multiscale method for simulation of carrier transport in large disordered systems, based on direct calculation of electronic states and electron-phonon coupling constants. It enabled us to obtain the never seen before rich microscopic details of carrier motion in conjugated polymers, which led us to question several assumptions of phenomenological models, widely used in such systems. The macroscopic mobility of disordered poly(3-hexylthiophene) (P3HT) polymer, extracted from our simulation, is in agreement with experimental results from the literature. 2Nenad Vukmirović et al.Charge carrier motion in disordered conjugated polymers: a multiscale ab-initio study Semiconducting conjugated polymers have been used in many electronic applications from field-effect transistors, 1,2 light-emitting diodes 3,4 to solar cells 5,6 due to relative ease to synthesize and mold them into different shapes. However, one of the major bottlenecks in conjugated polymer applications is the low carrier mobility. 7 There is therefore a great interest to understand