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Transition metal oxide materials with high theoretical capacities have been studied as substitutes for commercial graphite in lithiumion batteries. Among these, SnO₂ is a promising alloying reaction-based anode material. However, the problem of rapid capacity fading in SnO₂ due to volume variation during the alloying/dealloying processes must be solved. The lithiation of SnO₂ results in the formation of a Li₂O matrix. Herein, the volume variation of SnO₂ was suppressed by controlling the voltage window to 1 V to prevent the delithiation reaction between Li₂O and Sn. Using this strategy the unreacted Li₂O matrix was enriched with metallic Sn particles, thereby providing a pathway for lithium ions. The specific capacity decay in the voltage window of 0.05-3 V was 1.8% per cycle. However, the specific capacity decay was improved to 0.04% per cycle after the voltage window was restricted (in the range of 0.05-1 V). This strategy resulted in a specific capacity of 374.7 mAh g -1 at 0.1 C after 40 cycles for the SnO₂ anode.

A novel tailor-made multilayer composite polymer electrolyte, consisting of two outer layers of electrospun polyacrylonitrile (PAN) and one inner layer of poly(vinyl acetate) (PVAc)/poly(methyl methacrylate) (PMMA)/poly(ethylene oxide) (PEO) fibrous membrane, was prepared using continuous electrospinning. These membranes, which are made up of fibers with diameters in the nanometer range, were stacked in layers to produce interconnected pores that result in a high porosity. Gel polymer electrolytes (GPEs) were prepared by entrapping a liquid electrolyte (1 M LiPF6 in ethylene carbonate/dimethyl carbonate) in the membranes. The composite membranes exhibited a high electrolyte uptake of 450-510%, coupled with an improved room temperature ionic conductivity of up to 4.72 mS cm-1 and a high electrochemical stability of 4.6 V versus Li/Li+. Electrochemical investigations of a composite membrane of PAN-PVAc-PAN, with a LiFePO4 cathode synthesized in-house, showed a high initial discharge capacity of 145 mAh g-1, which corresponds to 85% utilization of the active material, and displayed stable cycle performance.

Recently, tin oxide (SnO2) has received significant attention for use as an anode material for next generation lithium-ion batteries (LIBs) owing to its high theoretical capacity (782 mAh g-1), which is more than twice of that of the commercialized graphite (372 mAh g-1). Several additional advantages, such as low cost, environmental friendliness, easy fabrication and natural abundance improve its promise. Although the theoretical capacity of SnO2 is high, volume expansion during cycling causes issue with cycling stability. In this study, an ordered mesoporous SnO2 was synthesized using a hard template (SBA-15), such that its mesoporous structure can buffer SnO2 particles from cracks caused by volume expansion. It can also allow effective electrolyte infiltration to ensure better reactivity of the active material with Li+ ions. The capacity of synthesized mesoporous SnO2 improved to 218.4 mAh g-1 compared regular SnO2 nanoparticles (69.6 mAh g-1) after 50 cycles at a rate of 0.1 C. Furthermore, carbon-coated mesoporous SnO2 enhanced capacity retention upon cycling (844.6 mAh g-1 after 50 cycles at 0.1 C) by insulating and preventing the cracking of the active material during lithiation and delithiation.