If electronics are the underpinning of our modern economy, then batteries are what make the world go round. And since its commercial introduction in 1995, the lithium-ion (li-ion) battery has been king.Over the past 30 years, a three-fold improvement in energy density has driven li-ion batteries far down the cost curve, from more than $3,000/kWh to approximately $150/kWh today, making li-ion the battery chemistry of choice for our toys, consumer electronics, medical devices, power tools, and increasingly, cars. Applications for household and grid storage that balance the intermittency of renewables are already hitting the market. Indeed, the $30 billion industry is expected to clock a blistering 11.6% annual growth rate through 2024, to a valuation of nearly $80 billion1.