Areas of research interest have focused on improving energy density, safety, rate capability, cycle durability, flexibility, and reducing cost.
[1] Materials that are taken into consideration for the next generation lithium-ion battery (LIBs) negative electrode share common characteristics such as low cost, high theoretical specific capacity, and good electrical conductivity, etc.
[4] At this time, significant other types of lithium-ion battery anode materials have been proposed and evaluated as alternatives to graphite, especially in cases where niche applications require novel approaches.
Dr. Leon Shaw’s research group from Illinois Institute of Technology has developed the Si@void@C microreactors which show exceptional test results to be LIBs anode.
[5] Tests from the Si@void@C microreactors demonstrated high Coulombic Efficiency of 91% during the first lithiation process, which is significantly higher than other reported silicon anodes.
No lithium plating was observed for the Si@void@C(N) electrode even after 1000 cycles at 8 A g−1, indicating their capability for ultrafast charging without compromising safety and capacity retention.
[12] This layered oxide can be produced in multiple forms including nanowires, nanotubes, or oblong particles with an observed capacity of 210 mAh/g in the voltage window 1.5–2.0 V (vs Li).
[15] Lithium anodes were used for the first lithium-ion batteries in the 1960s, based on the TiS2/Li cell chemistry, but were eventually replaced due to dendrite formation which caused internal short-circuits and was a fire hazard.
[16][17] Effort continued in areas that required lithium, including charged cathodes such as manganese dioxide, vanadium pentoxide, or molybdenum oxide and some polymer electrolyte based cell designs.
Recent work includes efforts in 2014 by researchers at Northwestern University who found that metallic single-walled carbon nanotubes (SWCNTs) accommodate lithium much more efficiently than their semiconducting counterparts.
For bulk electrodes, this causes great structural stress gradients within the expanding material, inevitably leading to fractures and mechanical failure, which significantly limits the lifetime of the silicon anodes.
[25][26] In 2011, a group of researchers assembled data tables that summarized the morphology, composition, and method of preparation of those nanoscale and nanostructured silicon anodes, along with their electrochemical performance.
The design had performance similar to conventional electrode polymer binders with exceptional rate capability owing to the metallic nature of the structure and current pathways.
In 2013, work on morphological variation by researchers at Washington State University used standard electroplating processes to create nanoscale tin needles that show 33% lower volume expansion during charging.
And nickel–tin anode is supported by an electrochemically inactive conductive scaffold with an engineered free volume and controlled characteristic dimensions, so the electrode with significantly improved cyclability.
[44][46][47] In this and related NiAs-type materials, lithium intercalation occurs through an insertion process to fill the two crystallographic vacancies in the lattice, at the same time as the 0.2 extra coppers are displaced to the grain boundaries.
[48] Although significant retention of structure is noted down to the ternary lithium compound Li2CuSn, over discharging the material results in disproportionation with formation of Li22Sn5 and elemental copper.
[49] Other approaches include making nanocomposites with Cu6Sn5 at its core with a nonreactive outer shell, SnO2-c hybrids have been shown to be effective,[50] to accommodate volume changes and overall stability over cycles.
[51] In 2011, researchers reported a method to create porous three dimensional electrodes materials based on electrodeposited antimony onto copper foams followed by a low temperature annealing step.
[53] Later work by Vaughey et al., highlighted the utility of electrodeposition of electroactive metals on copper foams to create thin film intermetallic anodes.
[68] In 2014, researchers at Massachusetts Institute of Technology found that creating high lithium content lithium-ion batteries materials with cation disorder among the electroactive metals could achieve 660 watt-hours per kilogram at 2.5 volts.
[74][75] LiFePO4 is a 3.6 V lithium-ion battery cathode initially reported by John Goodenough and is structurally related to the mineral olivine and consists of a three dimensional lattice of an [FePO4] framework surrounding a lithium cation.
This alignment yields anisotropic ionic conductivity that has implications for its usage as a battery cathode and makes morphological control an important variable in its electrochemical cell rate performance.
Powder X-ray diffraction patterns and transmission electron microscopy images revealed that the high phase purity and porous nanobox architecture were achieved via monodispersed MnCO3@SiO2 core–shell nanocubes with controlled shell thickness.
[80][81] In 2014, researchers at the School of Engineering at the University of Tokyo and Nippon Shokubai discovered that adding cobalt to the lithium oxide crystal structure gave it seven times the energy density.
Although researchers are still working to understand the exact electrochemical reaction mechanisms of TMFs, there is a general agreement that the strong metal-fluoride ionic bond contributes to poor kinetics within battery cells.
They also have the potential to substantially increase energy density because their solid nature prevents dendrite formation and allows the use of pure metallic lithium anodes.
[103][104] In 2014, researchers at Qnovo developed software for a smartphone and a computer chip capable of speeding up re-charge time by a factor of 3-6, while also increasing cycle durability.
Lithium manganate (LMO) particles were deposited on a carbon nanotube (CNT) sheet to create a CNT-LMO composite yarn for the cathode.
[132] The document gives a general procedure of the safety operations and performance tests on retired power battery cells, packs, and modules, but could not detail the steps and specifics.