India’s lithium-ion EV battery imports stood at roughly 3 GWh for 2022 and between April 2022 and January 2023, around 75% of it came from China. At the same time, India’s EV market is predicted to grow at a CAGR of 66% through to 2030, by which time it is expected to sell 10 million units annually.

This is promising for the sector, but it ties the country into dependence on a single chemistry battery whose supply may quickly be outstripped by demand (fig. 1). Also, China may reportedly be looking to throttle the supply of high performance magnets and certain rare-earth metals that are used extensively in EV motors, and the country already processes 65% of the global production of lithium. This has led India’s top planning body, Niti Aayog, to suggest a review of India’s li-ion battery imports with the intention to boost not only the country’s own EV battery manufacturing capacity, but also to find suitable alternatives.

This is especially important because even though the li-ion ecosystem has its variants — lithium ferro phosphate (LFP), lithium manganese oxide (LMO) and lithium nickel manganese cobalt oxide (LCO) — the reliance on the metal must be lowered as India does not yet mine or refine it in any appreciable quantity. The 5.9 million-tonne deposit reported in Jammu and Kashmir could be years away from commercial extraction, despite the government looking to auction the reserves soon.

Also, Chile’s president Gabriel Boric announced on April 20 that he would nationalise the country’s lithium mines. Chile is home to around 54% of the world’s lithium deposits and even though there are no indications yet that it will monopolise and dictate lithium’s prices and supplies, abrupt policy changes cannot be ruled out.

Fig. 2: A miner in Chile’s salt flats mining lithium | Image: Paz Olivares Droguett for NPR

The spot prices of lithium are also volatile, and upward swings due to (artificial) supply constraints could seriously hamper automakers’ profit margins. The metal itself is toxic (fig. 2), difficult to extract and its quick, volatile reaction with water calls for safer substitutes.

New alternatives to Li-ion

The following are the most practical alternatives that have much more easily available raw materials:

• Sodium-ion batteries: While the price of lithium hit an all-time high of $80,000/tonne in 2022, sodium carbonate retails for around $300/tonne. This makes sodium-ion batteries an exciting new alternative. Sodium is chemically similar to lithium but is abundantly available, and sodium-ion batteries are much less affected by lower temperatures. They also do not require cobalt or nickel. So even though their energy density at the moment is around 160WH/kg (~60% of li-ion’s), interest in this chemistry will improve the figure, just as the energy density of li-ion has gone up from under 100Wh/kg in the early 1990s to nearly 265Wh/kg today. Of course, the pace and funds behind battery research at the moment is also much greater than in the 1990s, so much faster progress can be expected.

  Fig. 3: BYD’s new Seagull EV with sodium-ion batteries | Image: ArenaEV

  China’s largest EV battery manufacturers, BYD and CATL, are already ready to launch batteries that use both lithium and sodium to lower the units’ costs (Fig. 3) without compromising their performance. In fact CATL has stated that its sodium-ion batteries offer excellent thermal stability, can be recharged to 80% in just 15 minutes, and they retain their performance at temperatures as low as -20 deg C. This is a distinct advantage over li-ion as they are difficult to charge at temperatures below 0 deg C. Sodium-ion batteries would thus be a good fit for India — the country does not manufacture such batteries at the moment — as it already has abundant salt deposits in rock salts, sub-sea brine and inland lakes (Fig. 4).

  Fig. 4: Around 75% of India’s salt comes from the west-central Gujarat |Image: Financial Express

• Zinc-ion: Zinc-ion batteries are another alternative that possess immense potential for scalability. The chemistry is not particularly energy-dense at ~81Wh/kg (compared to 100-265 Wh/kg for li-ion) but zinc is 100x more readily available than lithium and the batteries use a water-based electrolyte for much greater safety.The latter makes the chemistry especially suitable for tight, space-constrained and high temperature applications, such as for EVs in India, and for applications that mandate regulations against “thermal runaways” (fire). This is a critical factor as India has experienced a spate of EV fires. Investigations into the incidents have found that along with poor or non-existent battery management systems, the li-ion cells used were themselves of inferior quality, which led to uncontrolled heat distribution in the battery packs and thermal runaways.There have been issues reported with the zinc-ion chemistry as well, such as fast self-discharge and low cycling stability. But a research team in Saudi Arabia has reported breakthroughs that do not compromise the positive attributes of the battery.
• Metal-air: These batteries use a porous air cathode and a readily available metal for the anode, which makes them cheap and lightweight. The batteries work on the simple principle of oxidation and two of the most researched variants are aluminium-air and zinc-air.

  Fig. 5: Al-air cell showing the internal components | Image: cleanfuture.co.in

  The former has a high energy density of ~8100Wh/kg (theoretical), but it cannot be recharged like li-ion as the aluminum anode is fully consumed in the battery’s operation and must be physically replaced. However, at the moment the anodes are reported to be expensive. At the same time, though, India’s Hindalco is working with Israeli research firm Phinergy to develop an aluminium-air EV battery where the oxidized metal could be recovered for re-use.

  Zinc-air batteries are currently used in small applications, such as film cameras and hearing aids, but IIT Madras has developed a version for EVs at $150/kWh (very similar to li-ion’s $153/kWh in January 2023). It is mechanically rechargeable, which could be particularly useful in battery swapping stations.

• Solid State Batteries (SSBs): These are possibly the most promising alternatives to li-ion, as they use non-flammable electrolyte gels, instead of li-ion’s liquid electrolytes. This makes SSBs much more resistant to thermal runaways, it reduces the size of the batteries considerably, lowers their weight and increases their energy density — up to 2.5X that of li-ion. They are also faster to recharge (around 6x faster than commercial grade batteries).However, SSBs need constant contact between the component layers without the structure getting squished under pressure. Yet, they hold a lot of promise and have attracted investments from some of the biggest automakers, such as Ford, GM and BMW. Also, while most SSBs use lithium, a breakthrough with magnesium SSBs was made last year that would make the batteries much cheaper if manufactured commercially, as magnesium is abundantly available. Magnesium ions were known to have issues with flowing through an electrolyte at room temperature, but a research team at Tokyo University has announced that it has solved the problem.

Performance affects scalability

Li-ion batteries are the most popular for EVs because of their relatively quick recharge times, high energy density and light weight. None of its alternatives offer the same qualities yet, and so their production is limited to experimental volumes only. QpiVolta, a Bengaluru-based startup, is one of the few domestic manufacturers that have started manufacturing SSBs in India. But its technology uses lithium, as does the other indigenous SSB developed by Tamil Nadu-based Investus BioEnergy (IBE).

However, electric mobility is one of the primary enablers of low-carbon/no-carbon development and much more research is underway to bring the alternatives up to practical suitability. Specifically for India, it is estimated that it will need 903GWh of energy storage to decarbonise its transport sector by 2030, and most of it is anticipated to come from li-ion batteries. It must therefore be substituted by its alternatives if the country is to avoid spending the Rs 33,750 crores to set up 50GWh of li-ion cell manufacturing facilities in their entirety. The promising aspect is that both zinc-ion and metal-air batteries can be scaled up in production once proofs of concept — such as BYD’s new EV — are offered in the Indian market and the battery manufacturers realise their potential for profitability.