Lithium Titanate Anode Research Articles

Optimized Preparation and Potential Range for Spinel Lithium Titanate Anode for High‐Rate Performance Lithium‐Ion Batteries

Optimized Preparation and Potential Range for Spinel Lithium Titanate Anode for High‐Rate Performance Lithium‐Ion Batteries

A single-ion transport interfacial layer for solid-state lithium batteries

All-solid-state batteries possess several advantages including high safety, flexibility to use high-capacity metal anodes and are projected to be the next generation energy storage devices. Garnet-type cubic Li7La3Zr2O12 (LLZO) solid electrolyte is of particular interest due to its high ionic conductivity under ambient conditions and compatibility with Li metal. However, large electrode/electrolyte interfacial resistance constraints their development. Herein, the use of a highly lithium ion conducting dilithium phthalocyanine (Li2Pc) in ionic liquid as an interlayer is proposed to effectively suppress the high impedance at the interface thus improving the electrode-electrolyte contact. Fast Li+ mobility and high dielectric constant of dilithium phthalocyanine enhance the kinetics of Li+ transport across the interface. A significant reduction in overpotential and very stable stripping/plating cycling are observed in lithium symmetric cells upon introducing Li2Pc interlayer as compared to the use of bare tantalum doped lithium lanthanum zirconium oxide (LLZTO) electrolyte. Cells comprising interlayer-modified Li|LLZTO|LiFePO4 show high capacity with excellent cycling and rate capability. The performance of full cells using lithiated graphite and lithium titanate anodes has also been evaluated. This study presents a promising application of garnet electrolytes towards the advancement of solid-state lithium batteries.

Electrochemical Performance of Lithium-Ion Cells with Lithium- and Manganese- Rich Oxide Cathodes

State-of the-art (SOA) lithium-ion batteries (LIBs) being developed for transportation applications contain a transition metal (TM) oxide cathode and a graphite anode; both serve as host-matrices to house lithium ions during battery operation. The cathodes typically contains Li1+xNiaCobAlcO2 (NCA) or Li1+xNiaMnbCocO2 (NMC) oxides: both oxide chemistries contain Co, which is known to preserve the layered structure during lithium extraction/insertion reactions. However, the possibility of a global Co shortage and soaring costs has galvanized the LIB community to explore sustainable cathode chemistries, while maintaining cell performance (energy/power densities), safety and cycle/calendar life. In this context the U.S. Department of Energy (DOE) initiated the Earth-Abundant Cathode Active Material (EaCAM) Program for the development of sustainable cathode chemistries, based on earth-abundant elements.Materials of particular interest to the EaCAM program are the x Li2MnO3 ● (1-x) LiMnaNibZcO2 composites; here Z refers to various elements that could be included in the oxide structure. These lithium- and manganese- rich materials are considered attractive candidates because of their high specific capacities, zero cobalt content, and lower costs compared to the SOA oxides. We have been examining the electrochemical behavior of cells with these oxides, with a particular focus on the 0.3 Li2MnO3 ● 0.7 LiMn0.5Ni0.5O2 (LMR) compound.During this presentation, we will show results from battery cells, containing LMR cathodes and either graphite or lithium-titanate anodes. In particular, the use of a microprobe reference electrode to monitor the cathode and anode potentials will be discussed. The effect of activation on cell performance and the performance loss characteristics during cycling will be highlighted. We will show how cell impedance is affected by voltage hysteresis and the voltage fade that results from cycling. Our ultimate goal is to identify constituents and mechanisms responsible for the cell performance loss and develop solutions to mitigate this degradation.Acknowledgement: This document has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.

Fabricating Solid-State Electrolyte Li-Ion Cells through Composite Ionogel Electrodes

Fabricating high loading electrodes is essential to realizing Li-ion cells with solid-state electrolytes (SSE) that have relevant energy densities. However, making sure lithium can reach the active materials is complicated if the ions are isolated in the electrolyte phase. Low loading electrodes can prevent this issue by having all active material in contact with the SSE, but this tactic makes scalability and relevance to commercialization an issue. To this end we devised a strategy to create electrodes with sufficient Li+ conductance and 10 mg/cm2 loading to ensure cells without liquid electrolyte are capable of achieving high capacity utilization at room temperature. This was done through creating an ionogel-derived SSE and using the same ionogel based precursors to fabricate composite electrodes. By tuning the ratio of ion conducting polymer, carbon, and active material composite lithium titanate electrodes were cycled with an ionogel SSE in a half cell configuration that achieve theoretical capacity at C/5 and stable cycling at ~6 mA/cm2. Full solid state coin cells were also constructed with a composite lithium iron phosphate cathode, SSE, and composite lithium titanate anode. These cells were able to cycle at 1C rate at room temperature. We believe this version of cells is a scalable approach to solid state batteries. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

Enhancing lithium titanate anode performance through surface modification with fluorine and nitrogen co-doped carbon nanotubes

In this study, we explore the efficacy of fluorine and nitrogen co-doped carbon nanotubes (F@N-CNT) as a novel surface modifier for lithium titanate (LTO) anodes in lithium-ion batteries (LIBs). The integration of F@N-CNT enhances the electrochemical properties of LTO anodes by improving electrical conductivity and facilitating lithium-ion diffusion., Electrodes modified with F@N-CNT exhibited significant improvements in capacity retention, achieving 71 % capacity retention over 200 cycles at 2 C and delivering energy capacities up to 162.9 mAh g−1 at 0.2 C, with an impressive high-rate performance of 74.8 mAh g−1 at 30 C. This study demonstrates that F@N-CNT effectively forms a conductive network within the LTO matrix, resulting in superior high-rate performance and stability. It presents a comprehensive analysis of the microstructural changes induced by co-doping and elucidates their impact on the electrochemical performance, providing valuable insights into the design of high-performance anodes for future energy storage applications. This approach not only addresses the current limitations of LTO anodes but also introduces a scalable strategy for enhancing the overall functionality of LIBs.

Enhanced rate capability and capacity of LIB full cells achieved through aerosol jet printing

Thick lithium-iron phosphate (LFP) cathodes (31 mg cm−2) with rationally engineered pore structure and tortuosity were manufactured with an aerosol jet (AJ) printer. Cathode pore structuring was tuned by controlling the rate at which the printed ink dried. Slow-drying prints yielded smoother cathodes while fast-drying prints resulted in mesoscale structuring with substantial surface roughness. X-ray tomography further revealed that the rapid drying of AJ printed LFP cathodes produced low-tortuosity pore channels which were preserved after calendering. Full cells comprised of AJ print optimized LFP cathodes, with 30 mg cm−2 active material loadings, and capacity-matched, AJ printed lithium titanate anodes were assembled and electrochemically tested. Performance of the AJ printed full cells was compared to tape-cast (TC) full cells. At equivalent electrode loadings, compositions, and thicknesses, the AJ full cells outperformed the TC cells, averaging approximately 14% greater capacity per cycle after 100 cycles at a C/2 rate. Furthermore, at 1C, the AJ printed full cells realized a near two-fold increase in discharge capacity over the TC cells.

Characteristics and properties of anode materials for lithium-ion batteries

Lithium-ion secondary batteries (LIBs) are battery systems with high energy densities. They are essential components of todays information-rich, mobile societys portable, entertainment, computing, and telecommunications technology. After 1981, most of the research on anode materials mainly focused on the anode containing Li, such as LiAl alloy, LiC alloy, etc. These materials have high prices, unstable cycling performance, and are difficult to be commercialized. The successful commercialization of LIBs began in 1991 with SONYs manufacturing of petroleum coke-based anode materials. Among them, anode plays a crucial role in LIBs. Anode materials that have been commercialized include carbon, alloys, and lithium titanate. Lithium-ion batteries using carbon anode materials and lithium titanate anode materials can meet the needs of electric vehicles (EVs) and large-scale energy storage applications to a certain extent, and alloy anode materials can promote the energy density of LIBs. The properties of the commercialized anode materials are covered in this paper. Next generation anode materials such as silicon anode materials are also introduced.

Revealing the Equilibrium of Lithium Cations Across a Solid–Electrolyte Interface by T_1 NMR Relaxation

Battery fast charging is pivotal for broader acceptance of electric mobility. While demonstrated for lithium titanate (text {Li}_4text {Ti}_5text {O}_{12}, LTO) anodes, the underlying mechanisms are still poorly understood. Recently, NMR T_1 relaxation time constants of {}^7text {Li} in the bulk of LTO were found to change if the surrounding electrolyte was altered. It was explained by interdiffusion of mobile lithium ions between the two phases, facilitated by unpinning of polarons from surface defects and leading to a pseudocapacitive effect that potentially influences fast charging. This effect is explored further by systematically varying the lithium salt concentration in an aprotic electrolyte in contact with LTO. Spectrally resolved {}^7text {Li}T_1 NMR relaxation times were used as a measure for bulk concentration changes of paramagnetic polaronic charges in LTO. Correlation of electrolyte concentration and {}^7text {Li}T_1 showed qualitatively different behavior above and below a salt concentration of about 5 mM, leading to a relaxation dispersion maximum in the LTO bulk. At intermediate concentrations, relaxation was consistent with a {}^7text {Li} exchange equilibrium between LTO and electrolyte. Upon contact of the two phases, yet without insertion into an electrochemical cell or applying an external potential, lithium ions redistributed between LTO bulk and liquid electrolyte. The results can be understood analogously to the distribution of mobile lithium ions between two phases separated by a text {Li}^{+} permeable membrane. This is the first demonstration of such an equilibrium for non-faradaic lithium exchange at an interface between a solid ceramic electrode and a liquid electrolyte outside an electrochemical cell, substantiating our previous hypothesis of a polaron-supported mechanism. This study provides a basis for more quantitative (surface)-defect engineering, which is key to optimize battery fast-charging properties.

Light-weighting of battery casing for lithium-ion device energy density improvement

Battery casings are essential components in all types of lithium and lithium-ion batteries (LIBs) and typically consist of nickel-coated steel hard casings for 18650 and 21700 cell formats. These steel casings comprise over one quarter of total battery cell mass and do not actively contribute to battery capacity. It is therefore possible to achieve considerable battery performance improvements, in terms of device energy density, by reducing the mass of the battery casing. Following successful completion of an industry-academic technology programme of light-weighting battery casings, this paper reports our research activities to understand the practical performance of aluminium hard casings which are 63 % lighter than a state-of-the-art steel casing. A popular exemplary battery chemistry, Lithium Titanate anode / Lithium Iron Phosphate cathode, which is well-known for high power and good safety, was employed. Research investigations include (a) the optimisation of standard commercial LIB manufacturing process for aluminium casings, (b) the production of 18650 LIBs using aluminium casings, (c) electrochemical analysis and safety testing of the cells, comparing with those assembled with steel. The aluminium casings could readily be incorporated into standard commercial LIB manufacturing process with minimal process changes and provided a > 25 % boost to energy density. Crucially, stress testing of the cells revealed no added safety challenges associated with the material change. Lightweight Al hard casings have presented a possible solution to help address weight sensitive applications of lithium-ion batteries that require high power (or high energy). The approaches herein are battery materials agnostic and can be applied to different cell geometries to help fast-track battery performance improvements.

Nitrogen-sodium co-doping improves cycle performance of lithium titanate anode materials at high rate

Li4Ti5O12 is a lithium-ion battery cathode material with great potential for development because of its “zero-strain” characteristics, but its low lithium ion diffusion and conductivity rate lead to poor rate and cycling performance. NaN-LTO, a nanorod-like material with oxygen vacancies on the surface, was prepared by calcination after hydrothermal reaction using sodium molybdate as the sodium source and L-cysteine as the nitrogen source and structural guiding agen, while achieving co-doping of N and Na at the O and Li positions in situ respectively. The effects of N and Na co-doping on the crystal and electronic structures were revealed. The electrochemical test results show that rate and cycle performance of NaN-LTO are greatly improved, which can reach 126.0 mAh/g at 20C (1C = 175 mAh/g), 126.9 mAh/g after 1000 cycles with a capacity retention rate of 100.7% and the capacity retention rate is 74.0% after 3000 cycles. The co-doping strategy of Li-site and O-site provides a new modification idea to enhance the electrochemical performance of lithium titanate. Meanwhile, the preparation cost of lithium titanate can be reduced by the partial replacement of Li by inexpensive Na.

Hydrometallurgical recycling of lithium-titanate anode batteries: Leaching kinetics and mechanisms, and life cycle impact assessment

Since the inception of Li-ion batteries, the chemistry of cathode and anode materials has changed time-to-time. In recent times, the lithium-titanate (LTO) anode material has gained attention due to a higher surface area (100 m2/g) than the usual graphite-made anode (3 m2/g). The development of a new recycling strategy, in particular, to deal with spent LTO batteries, is therefore urgently needed as plenty of batteries deployed in electric vehicles are near to completing their lifespan. Herein, we demonstrate the recycling of spent LTO batteries by optimizing the parametric influence of H2SO4 concentration, H2O2 dosage, agitation speed, temperature, and time for lithium and titanium leaching from the anode material. About 92% titanium and 98% lithium were efficiently leached from the anode powder using a 3.5 mol/L H2SO4 solution with 25 vol% H2O2 at a pulp density of 5 wt./vol.%, temperature 120 °C, and time 120 min. The leaching examined in the temperature range between 60 °C and 120 °C with respect to time showed the best fits to the kinetic model governed by the logarithmic rate law. The apparent activation energies of titanium (78.9 kJ/mole) and lithium (11.3 kJ/mole) indicated two different mechanisms governed by chemically controlled and diffusion-controlled reactions, respectively. It indicated that both metals’ leaching proceeded through lixiviant diffusion on the LTO surface, which was corroborated by the instrumental analyses of the untreated LTO sample and the leached residues. A life-cycle assessment suggests the need for discharge acid for recycling within the system due to a terrestrial ecotoxicity of 97.09 kg DCB-eq; however, the ionizing radiation and eutrophication potential are found to be negligible.

γ-Graphyne adjusted diffusion–capacitance behavior of lithium titanate for boosting high-rate and wide-temperature lithium storage

Pursuing high power density and wide-temperature environmental adaptability is vital to broadening the utilization of lithium titanate (LTO) anodes in start-stop batteries of electric vehicles. Here, we introduce γ-graphyne, an emerging carbon allotrope composed of sp- and sp2-hybridized carbon, to encapsulate LTO particles via a one-pot ball milling. γ-Graphyne with a two-dimensional π-conjugated structure contains abundant electron-rich acetylene linkages in favor of fast electron conduction and, more importantly, it is a promising Li-ion host delivering a certain capacitance within the typical potential window of LTO. The optimum LTO/γ-graphyne composite shows outstanding rate capability (83 % retention of 10C compared to 0.5C), long-term cycling stability (91 % retention over 1000 cycles at 2C), and high low-temperature retentivity (102 mAh g−1 at −20 °C after 500 cycles at 1C, 63 % utilization of that at 25 °C). The impressive performance arises from adjusted diffusion–capacitance Li storage behavior with significantly reduced plateau-potential polarization and enhanced interfacial ionic migration capability. This work highlights an electrochemical active, highly conductive alkyne carbon candidate endowing full-climate applications of LTO anodes.

High-Temperature Electrochemical Performance of Lithium Titanate (Li4Ti5O12) Anode Material in Secondary Lithium-ion Batteries

Lithium titanate (Li4Ti5O12, LTO) anodes are preferred in lithium-ion batteries where durability and temperature variation are primary concerns. Previous studies show that LTO anodes perform well, in terms of cyclability and rate capability, at ambient and low temperatures. This work reports the effect of extreme temperature conditions on the electrical and electrochemical properties of LTO anodes. The capacity and C-rate performance of the LTO anode is observed to improve from ambient temperature up to 70 °C. Increasing the temperature above 80 °C has a detrimental effect on performance, and it ultimately fails at 130 °C. As the rate capability and discharge capacities of the LTO anode increase with temperature up to 70 °C, the increase in temperature up to a certain level can facilitate faster charging of lithium-ion cells.

Correlation of Electrochemical Characteristics with Structural, Optical, and Electrical Properties in Tungsten-Doped Li4Ti5O12 Anodes

Tungsten (W) doping boosts electrochemical performance of the lithium titanate (LTO) anode accredited to varied fundamental features, i.e, crystalline and electronic structures and electronic/ionic conductivities. W6+ induces partial reduction of Ti4+ ions to Ti3+ owing to increased conduction electrons/energy levels, causing a reduced band gap of LTO and increased room-temperature electronic conductivity to a maximum of 1.3 × 10–6 S cm–1 for an optimal W concentration of x ∼0.15. An improved room-temperature Li-ion conductivity/diffusivity of 6.5 × 10–8 S cm–1/1.6 × 10–12 cm2s–1 for x ∼0.15 is owed to increased lattice spacing on the substitution of W6+ at Ti4+ octahedral sites. Temperature-dependent impedance over 25–300 °C depicts increases in ionic and electronic conductivities from 10–8 to 10–4 S cm–1 and 10–8 to 10–6 S cm–1, respectively. Activation energies Ea of 0.48–0.50 eV for both undoped and doped LTOs illustrate the same conduction mechanism of Li ions through 8a-16c-8a pathways. Electrochemical characteristics improve in correlation to the type of dopant, doping concentration, substitutional site of dopant, resulting structural variations, and varying electronic/ionic conductivities and conduction mechanisms.

Spinel lithium titanate anode/polyether sulfone nanocomposite synthesized by pulsed laser ablation method for optoelectronic applications

Nowadays, to increase the usage of energy storage applications like electric cars or stationary storage, the cost of these manufacturers must be reduced. Our present study focuses on an alternate electrode production approach to suit the needs of today's lithium ion battery’s cost efficiency by using an eco-friendly method, the pulsed laser ablation method in liquid media technique, which was used for the first time to synthesize spinel lithium titanate anode, Li4Ti5O12 nanoparticles (LTO NPs), and incorporate them with polyether sulfone (PES) in just one step to form a PES/LTO nanocomposite. The evidence from XRD showed that the nanocomposite film is formed as a crystalline phase from a cubic spinel structure corresponding to LTO, with crystalline sizes around 9.4 nm. Furthermore, SEM revealed a semi-spherical distribution of LTO NPs throughout the PES matrix. Also, the elemental analysis provides the elemental peaks for C, S, Ti, and O, and no other elemental peaks do, confirming their purity. Moreover, the FT-IR investigation affirmed the interaction between PES and LTO NPs via the sulfone group with the breakage of the sulfur and oxygen double bond and the formation of a new link between SOLa and SOTi that may be responsible for the emergence of this band. Also, the absorption study confirmed the formation of localized states between occupied and unoccupied molecular orbital bands is made feasible by the chemical linkages between PES chains and LTO NPs. As a result of the dielectric investigation, LTO NPs are a good choice for usage as dopants to enhance the electrical characteristics of PES polymer. Overall, the PES/LTO nanocomposite films' improved dielectric and optical properties make them appropriate for energy storage applications.

An insight into lithium-ion transport in germanium-doped lithium titanate anode through NMR spectroscopy and post-carbonization for anode applications in lithium-ion battery

Adapting toward lithium titanate as a negative electrode for lithium-ion batteries led to the safest and long-lasting battery technology, especially for electric vehicle applications. However, the poor conductivity and lithium-ion diffusion of lithium titanate have to be addressed for widespread usage in next-generation E-mobility. The lithium-ion motion inside lithium titanate and germanium-doped lithium titanate was investigated through pulsed-field gradient nuclear magnetic resonance spectroscopy and temperature-dependent ionic conductivity studies. The superior charge carrier mobility of germanium enhanced the lithium-ion diffusion in lithium titanate significantly to 1.48 × 10−8 cm2 s−1 in Li4Ge0.1Ti4.9O12 at 500 °C. While germanium improves the ionic diffusion, an ex situ carbon coating was adapted over the sample for electronic conductivity enhancement. Samples with two different carbon contents (5 and 10 wt. %) were examined for electrochemical analysis. Significant improvements in battery performance were observed on carbon-coated germanium-doped lithium titanate. The carbon-coated sample gave superior initial performance (191 and 178 mAh g−1 for 10 and 5 wt. % carbon at 0.1C) than the pristine lithium titanate and preserved the exceptional capacity retention over a thousand cycles at 1C rate.

Coating lithium titanate anodes with a mixed ionic-electronic conductor for high-rate lithium-ion batteries

Lithium titanate (Li4Ti5O12; LTO) is a promising anode material for fast (dis)charging Li-ion batteries (LIBs). However, its low Li diffusion coefficient and electronic conductivity limit its applications. Here, we uniformly coat the LTO surface with a 1.6 nm layer of partially lithiated titania (LixTiO2, x ≈ 0.5), which is found to be a mixed ionic-electronic conductor (MIEC), using a simple solid-state method. The MIEC layer simultaneously transfers electrons and Li-ions, facilitating efficient charge transfer to (de)lithiate LTO over the entire particle surface. MIEC-nanocoated LTO exhibits highly improved capacity retention and rate capability than pristine LTO; based on electrochemical simulations, MIEC nanocoating causes performance enhancement by maximum surface-area utilization for charge transfer. Furthermore, electrochemical impedance spectroscopy and density functional theory calculations confirm facile ionic transport and high electronic conductivity of LixTiO2 nanolayer. This general strategy of MIEC nanocoating can boost the electrochemical performances of various insulating electrodes, maximizing the materials utilization.

Quenching-Induced Defects Liberate the Latent Reversible Capacity of Lithium Titanate Anode.

Interest in defect engineering for lithium-ion battery (LIB) materials is sparked by its ability to tailor electrical conductivity and introduce extra active sites for electrochemical reactions. However, harvesting excessive intrinsic defects in the bulk of the electrodes rather than near their surface remains a long-standing challenge. Here, a versatile strategy of quenching is demonstrated, which is exercised in lithium titanate (Li4 Ti5 O12 , LTO), a renowned anode for LIBs, to achieve off-stoichiometry in the interior region. In situ synchrotron analysis and atomic-resolution microscopy reveal the enriched oxygen vacancies and cation redistribution after ice-water quenching, which can facilitate the native unextractable Li ions to participate in reversible cycling. The fabricated LTO anode delivers a sustained capacity of 202 mAh g-1 in the 1.0-2.5V range with excellent rate capability and overcomes the poor cycling stability seen in conventional defective electrodes. The feasibility of tuning the degree of structural defectiveness via quenching agents is also proven, which can open up an intriguing avenue of research to harness the intrinsic defects for improving the energy density of rechargeable batteries.

Electrochemical characterizations of carbon decorated tin doped lithium titanate for lithium-ion battery anode applications

Lithium titanate (Li4Ti5O12) anode materials are widely popular because of their exceptional structural properties that could offer extremely long life and high current rate with safe operation. In-depth research works have been going on to mitigate the limiting factors like poor conduction and diffusion of lithium titanate for the electrode applications in the lithium-ion battery. Elemental doping and surface coating were found to be promising methods to overcome these challenges and enhance the capacity for widespread application. Herein, ex-situ carbon-coated tin (Sn4+) doped lithium titanate was synthesized via conventional solid-state synthesis. Its electrochemical performances were analyzed and compared with its pristine phase by making half cells with lithium. The results were highly promising as the Li4Sn0.05Ti4.95O12 with 5 wt% carbon coating exhibited significantly reduced cell impedance (Rct = 49.48 Ω), enhanced electrode lithium-ion diffusion coefficient (D = 2.40×10−11 cm2 s−1), and superior specific capacity (Q = 173.1 mAh/g at 0.1 C) over pristine lithium titanate (Rct = 274.2 Ω, D = 2.71×10−12 cm2 s−1, and Q = 145 mAh/g). The cell could also run for 1000 cycles with minimum capacity fade (82 % retention) at a 1 C rate.

Diffusion kinetics in germanium doped lithium titanate anode material through potential sweep analysis

The inevitable demand for the energy sources for the present world's living has increased the pace of exploration towards developing sustainable and superior performing energy storage devices. Lithium-ion battery technology has been in the front since its invention. The introduction of spinel structured lithium titanate (Li4Ti5O12) as an anode material for lithium-ion batteries led to revolutionary improvements in rate-capability, long cyclability, and safety. The diffusion kinetics studies have been carried out on germanium doped lithium titanate (Li4GexTi5-xO12, x = 0.05, 0.10, 0.15, and 0.20) through cyclic voltammetry analysis. The studies revealed that the lithium-ion kinetics in the lithium titanate has significantly improved the electrochemical performance through germanium incorporation. The lithium-ion diffusion coefficient of Li4Ge0.1Ti4.9O12 (1.12×10−11 cm2 s−1) was found to have one order higher than that of the pristine phase (2.71×10−12 cm2 s−1). This enhancement in the lithium-ion diffusion has pushed the discharge capacity of Li4Ge0.1Ti4.9O12 to 161 mAh g−1 from 145 mAh g−1 at 0.1C rate.