Sr0.95In0.05Li2Ti6O14: A high performance lithium host material

• Sr0.95M0.05Li2Ti6O14 is fabricated as anode materials for lithium-ion batteries.
• Na+, Cu2+, and In3+ ions are used as Sr-site dopants for SrLi2Ti6O14.
• Sr0.95In0.05Li2Ti6O14 shows improved lithium storage capability.
• In-situ XRD observation is performed to study the lithiation process.

Via Sr-site substitution, a series of Sr0.95M0.05Li2Ti6O14 (Mz+ = Na+, Cu2+, In3+) are prepared as anode materials for lithium-ion batteries. It is found that the introduction of Na+, Cu2+ or In3+ into the crystal lattice can reduce the charge-transfer resistance and improve the lithium-ion diffusion coefficient of SrLi2Ti6O14. Especially for In3+-doping, it exhibits more obvious effect on these improvements. Furthermore, the substitution of Sr2+ by In3+ can also enhance the electronic conductivity via inducing a reduction of an equivalent number of Ti cations from Ti4+ to Ti3+. As a result, Sr0.95In0.05Li2Ti6O14 shows the best cycle and rate properties among all as-prepared samples. In addition, in-situ observation also proves that Sr0.95In0.05Li2Ti6O14 is a zero-strain lithium storage compound during charge/discharge process. As a result, it delivers a lithium storage capacity of 136.4 mAh g−1 at 200 mA g−1, 126.3 mAh g−1 at 400 mA g−1 and 121.0 mAh g−1 at 600 mA g−1. In contrast, SrLi2Ti6O14 only presents a charge capacity of 138.3 mAh g−1 at 200 mA g−1, 120.3 mAh g−1 at 400 mA g−1 and 111.3 mAh g−1 at 600 mA g−1. Therefore, In3+-doping is an effective method to enhance the electrochemical properties of SrLi2Ti6O14.

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