Battery Introduction

Energy storage in chemical batteries has a long history but this page focusses only on cells and batteries relevant for grid Battery Energy Storage (BESS), solar energy storage, and mostly transport. Basically, electrical energy storage in batteries can be extremely efficient (over 98% round trip), safe, and extremely long-lasting (decades to centuries for thousands of cycles) and both high energy and high power sufficient for vertical take-off aircraft, cars, bicycles and boats.

Batteries in 2024

The Panasonic high Nickel content cells in Teslas newer cars store over 250 Wh per Kg mass and cost under USD 120 per KWh capacity but Tesla also buy Lithium Iron Phosphate cells from CATL which are much cheaper, can sustain more charge cycles and use no expensive/rare metals. A nice review of battery chemistries was written in 2024 by recurrentauto. Many kinds of battery have enough energy and power for electric bikes but lithium chemistries are the current leaders: Lithium polymer, Lithium Iron Phosphate, Lithium Cobalt Oxide, and Lithium Manganese Aluminium are common though the specific chemistries and constructions are merging and mixing. Lithium Titanate cells like the Toshiba SCIB cell are commonly available in an almost everlasting Titanium high power format that would be perfect for multiple cycles per day grid cycling or small batteries for repeated charges per day with no degradation. Sulfur is very cheap and could now be used for batteries because it has just had its cycling properties enhanced via a nanofibre kevlar mesh separator. StoreDot is selling rapid charging, high energy battery cells and shown over 1000 cycles with minimal capacity loss. These lightweight 300+ WHr/Kg cells would be ideal for electric bicycles and cars. Sodium batteries have been commercialised by CATL, Natron Energy and Faradion and they are cheap and getting cheaper and have huge advantages for cold temperature charging and rapid charging as well as price so may replace other chemistries for stationary storage. Form is manufacturing large Iron Oxide chemistries which should enable the lowest priced battery for grid storage because Iron is so available and cheap. Cobalt Oxide was in all the early Lithium Ion batteries but it has two serious problems because it evolves Oxygen when heated to relatively low temperatures (above 170 Celsius) allowing the organic electrolyte to burn or explode and also because Cobalt is expensive and its mines have serious environmental problems. A solid-state battery with a pure Lithium metal anode is now available with a high energy density from Sakuu - currently 800 Watt hours per Litre. In 2024, Samsung finally started shipping its first solid state Lithium battery for cars. Ultimate Lithium batteries will probably use a Lithium metal anode and some semi-solid lithium-ion batteries with Lithium metal electrodes were being sold in 2023 in consumer power-banks. Lithium cells can can sustain 10000 charges or more and recent scientific understanding has pushed cycle life well past 10000 charges and still with 85% of its original capacity. In 2019, it was shown that using only commercial publically available cells and electrolytes (no proprietary secrets at all) , a car with these cells could travel many millions of miles over its life or the cells would last over 20 years in a grid backup storage battery. In 2022, Dahn and his replacement academics demonstrated a lower voltage high Nickel cell NMC532 with a cycle life up to 100 years. For the longest lifespan, electrodes should use single-crystal metal oxide compounds and never be charged above 75%. Silicon electrodes with new electrolyte chemistry from Sekisui Systems or Enevate have three times normal 2010 energy storage capacity and ORNL have made a new kind of cell using solid compounds of Lithium and Sulphur without any liquid electrolyte with four times the energy of current lithium ion batteries. One Japanese group with a strong pedigree called Power Japan Plus have designed a novel battery with dual carbon electrodes.

Multiple groups are working solid-state Lithium batteries and hundreds of millions of dollars has been invested in a few companies preparing to sell solid-state batteries: Volkswagen invested one hundred million dollars in QuantumScape in 2018, Dyson invested 90 million USD in Sakti3 in 2017 and in both 2017 and 2018, John Goodenough and Maria Helena Braga published papers describing novel designs of solid-state cells that increase capacity with time and have been tested over 23000 cycles already. solid-state batteries The first commercial uses of solid-state batteries may be from SolidEnergy who plan to fly them in drones. John Goodenough has done much to enable high energy batteries and pollution-free transport.

More exotic Lithium metal, or Lithium Silicon are available already. Currently, Lithium Iron Phosphate is ideal for stability over temperatures and charge cycles (> 3000) and is available now in high power (A123 offers over 60 Amps from a 2.3 Amp hour cell) or low cost (CATL <80 Euros per KW-hour) chemistries . Lithium polymer can be high power but needs much more care and can burst into flames with a bit of damage and generally fades faster. Lithium Manganese is both high capacity and is more stable than older "Lithium Ion" batteries (made with just Cobolt Oxide) plus it can be recharged over 500 times if properly managed. Leydon energy recently announced a new Lithium battery chemistry that seems ideal for most uses including e-bikes. In 2014, Oxis energy was preparing to produce lithium sulphur batteries for UK military and transport uses and in 2019 made their own factory in South America but then went bankrupt in 2021. In 2024, Lyten and a few other companies are actually already manufacturing Lithium Sulfur batteries which should be lighter, higher capacity, and cheaper than alternative similar chemistries. CATL and BYD have produced advanced new LFP chemistries (Shenxing Plus) for cars that can charge at a 4C rate and last for 8000 cycles so most car manufacturing and stationary storage is moving to LFP which is the cheapest in 2024 The Chevy Bolt is changin to LFP batteries. Conventional Lithium Ion batteries are very high performance and medium durability but can have reduced resistance if they are built without any water vapour around or if the cell surface interface can be annealed to remove the damaging hydration. DotStore makes lithium cells that can be charged in just 5 minutes and they will be used in batteries by the VinFast car company in Vietnam.

All batteries can be damaged by improper use. Lithium ion batteries are very easy to damage if they get too hot, too cold, punctured, overcharged or flattened. Sometimes, they even burst into flames and burn down your house so be careful - well the old ones could but that is much less likely with the newer chemistries. So, for safety, and longevity, the electric bike needs a good charger and a careful battery management system when running. Each cell in a battery - needs - to be monitored as it charges and when in use. This absolutely requires independent awkward wires to each and every cell with completely reliable computers and power control electronics - unless each cell has its own internal protection circuit. Kalkhoff Lithium Manganese batteries come with a two-year warranty and seem to be very reliable in practice with very little capacity loss over 1-year. Tesla's Panasonic cells are degrading slower than expected especially after the first year and most should last longer than the vehicle itself. Lithium batteries are cheap now and only a minor factor in the overall cost per distance of an electric bike but shipping them is difficult and they need guarantees for safety. If you are interested in building ore replacing your own electric bicycle battery pack , start on this electrickbike page. In 2015, cost comparison for vehicle batteries showed how scaling and new research are more than doubling energy storage per weight.

Other battery chemistries

Nickel Metal Hydride(NiMh) batteries have a good reputation, are cheap and are not as fragile as Lithium batteries but they have low charging efficiency (losing about one third of the energy put-in) and cannot be discharged as quickly as poisonous Nickel Cadmium or high-power lithium chemistries. Also older (most common) NiMh batteries gradually lose their charge. After a bit of misuse many old NiMh batteries could lose most of their charge in a few weeks. Newer NiMh batteries are called "ready for use" or hybrid batteries and use a new electrical separator to reduce charge leakage. Newer NiMh batteries have names like: Hybrio, Eneloop, or Annsman MaxE but are not yet available in tagged cells for making into packs for bikes. Nickel Zinc batteries are very new and should be cheap and may be worth considering but reliability in electric bikes is not known yet. Nickel Zinc batteries are now being aimed at halving the weight of the standard 12V lead-acid batteries common in cars and should have similar costs.

Back to Personal Home Page E-bikes, pedelecs, electric bicycles Green Transport Renewable Energy